HashEx Security Blog - Medium

Digital Identity: Protecting Your Sensitive Data

Dmitry Mishunin — Wed, 25 Oct 2023 11:23:10 GMT

Every bit of information that we publish online helps create a digital identity. Essentially, it’s a collection of data related to everything a person has ever said and done online. Photos, texts, fingerprints: all that data is collected together and stored somewhere being used in case we need to prove our identity online.

Storing this much sensitive data is convenient on one hand. On the other, it poses a significant danger: any breach can lead to the data being used by malicious actors, which makes its protection a vital step. So the question is, how do we minimize the risk of breach? The answer comes from an unexpected solution.

Artificial Identity

Digital identity can be viewed as usable data, but the truth is, it’s the closest we’ve ever been to creating a digital copy of a human that possesses all the available data about them. Science fiction aside, it makes perfect sense to throw in artificial intelligence and see what happens.

One of the less-discussed applications of artificial intelligence is arguably its primary function –

the possibility of creating a self-learning digital identity.

Machine learning in particular is what can contain and develop the information from a person’s digital profile. And by that, we don’t mean just the information someone voluntarily shares with the world. Aside from our profiles on social media or photos, there are gigabytes of information about each and every person online. Medical records, tax information, and preferences down to the choice of favorite fruit or preferred brands of milk. If used properly, it can provide an endless source of necessary information for an AI assistant.

However, before we begin theorizing about a potentially self-sufficient analog of Siri, we should consider the fact that in case of a breach, all that data can be used by malicious actors. This means that protecting said data is the primary task that should precede any attempts at implementing this theoretical development.

Where Does Cryptography Сome In

If there is a valuable element of blockchains that can be applied for security, it’s cryptography. Specific techniques are used to guarantee data safety and the best way to understand the functionality of each, is to review them one by one. Let’s take a look at the ways cryptography is applied in blockchain.

Cryptographic keys, better known as private keys are used for signing transactions. These signatures are used to prove the transaction’s authenticity and origin. They can be used to restrict access to sensitive information.
Cryptographic hash functions represent data in a string of characters. Changes in the data immediately change the hash itself. Every block in the chain contains the hash of the previous one. This helps to structure information and provide data stamps.
Cryptography is used in both PoW (proof-of-work) and PoS (proof-of-stake) techniques specifically for safety reasons. Both are used to validate transactions.
Encryption can be used for especially sensitive information.
Cryptographic protocols known as ZKPs are used for the prover in case they need to confirm possession of certain information without revealing the information itself.

However, one of the essential points is the fact that cryptography allows encoding the information in seconds, while decoding may take longer even if the decoder possesses everything required. Cryptography can potentially deliver high levels of protection for any type of stored information: it’s much harder to break into a ledger secured by cryptography than into any other time of digital storage. And nowhere it’s more relevant than with personal data.

How Would That Work

The fusion of AI and cryptography unlocks numerous possibilities for developers. A well-secured digital identity could revolutionize the world of digital assistants, creating sophisticated systems capable of analyzing medical history, behavioral patterns, and offering personalized recommendations. However, strict authorization, exclusively controlled by the owner, is essential to ensure no unauthorized access.

A well-secured digital identity can be a tremendous improvement in the industry of digital assistants. The first thing that comes to mind is preparing all the necessary accommodations according to the owners’ preferences. But that is just the tip of the iceberg.

Imagine a digital therapist that knows medical history and symptoms, and can analyze behavioral patterns based on a person’s digital persona as well as private information. Like a human therapist, this system will become more sophisticated and possibly more qualified with time and experience.

This system could be used for accounting, activities, and so on. It’s important to realize that an assistant like this is only possible if we eliminate any possibility of unauthorized access. And authorization can come exclusively from the owner. The synergy between blockchain and cryptography is absolutely necessary for protecting this data.

Before we get over-excited about the automated bureaucracy of the future, let’s consider several other possibilities.

For instance, let’s imagine AI lawyers. A lawyer like this could find a precedent in mere seconds. Something that would take a human lawyer hours or days. Some might argue that this can save lives. An AI lawyer can even predict the most likely outcome of the case based on evidence, witness statements, and even any input data about the jury.

But since AI can’t convey emotion, it will be useless as the main attorney in court. If we involve AI in the legal system, it might sway the decision in favor of logic somewhere where emotions could’ve made all the difference. It will, however, make a great counsel to a human attorney or even a regular user looking into settling certain matters in court.

A similar issue occurs when we consider AI medical consultants. Yes, it can analyze data and suggest a course of action. It can even detect an illness that a human doctor may not be aware of due to a lack of experience and do it fast.

But medical expertise isn’t always based on cold data. More importantly, where logic would suggest surgery, a doctor could recommend medical trials or a different treatment altogether. It’s highly unlikely that we will ever be able to trust pure logic when it comes to making life-altering decisions. And in this case, AI lacks ‘heart’.

Still, coming back to the original point, even when we use AI only for assistance, it gains access to our most private information: health conditions, certain events, statements, confessions, etc. Cryptography allows encoding data and limiting access, for instance, allowing the AI assistant to obtain the necessary information. At the same time, cryptography can limit the AI’s actions to avoid data leaks. The conversation regarding what information can be considered sensitive and who can access it in case of an investigation or signs of possible danger to a person themselves or others is ongoing. Even knowing that this data can be obtained with a court order can be a strong argument against keeping large amounts of private information in one place. This is why for now this futuristic assistant is just a theory. But a theory that shows us the potential of the technology itself.

Digital Identity: Protecting Your Sensitive Data was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Scam Report: September 2023

Polly Traore — Tue, 03 Oct 2023 00:09:12 GMT

In the tumultuous month of September, the crypto realm was shaken by the prominent Mixin Network incident, capturing major attention. Yet, it wasn’t the sole setback. The DeFi landscape also grappled with substantial damages from rug pulls and code flaws.

For a clearer perspective, we’ve segmented the attacks into two types: technical and non-technical. Technical attacks include smart contract weaknesses and oracle interferences, while the non-technical cover exitscams and rug pulls. Stay vigilant with HashEx insights!

Top External Threats

Mixin Network $200.000.000

Mixin Network, a leading decentralized digital asset transfer platform, faced a cloud service vulnerability exploit on September 23, 2023. This incident resulted in a significant loss of $142,041,764 across Ethereum and Bitcoin chains. Skillfully navigating the networks, the attacker transferred assets, converting them to DAI and Ethereum, totaling $118.66M by September 26th on Ethereum. Concurrently, 891 BTC, valued at approximately $23,381,764, was extracted from the Bitcoin chain.

CoinEx $53.000.000

On Sep 12, 2023, the crypto community felt the tremors as CoinEx’s hot wallets faced a formidable breach. Through a private key compromise, a staggering 52,847,077 USD was siphoned off across 9 distinct chains. The audacity of the attackers was evident as they rerouted the funds to their personal addresses.

Stake Wallet $42.000.000

The digital landscape was rattled on Sep 04, 2023, as Stake.com’s hot wallets fell victim to a sophisticated exploit, leading to a substantial depletion of $41,408,903 across Ethereum, Binance Smart Chain, and Polygon networks. Stake.com, a renowned crypto gambling protocol, disclosed the breach of its multifaceted hot wallets on the said date. The assailant infiltrated the private keys, extracting a myriad of tokens and incurring colossal losses. However, Stake.com has fortified user confidence, asserting the security of their funds and the uninterrupted functionality of other wallets. The malefactor meticulously allocated the purloined assets across the impacted chains, initially relocating assets from Stake.com’s hot wallets to a principal address, subsequently dispersing them amongst various EOA addresses. A staggering $13 million in diverse tokens still reside in the affected addresses across the trio of networks.

Coindroplet $23.100.000

On Sep 06, 2023, the crypto sphere was jolted by a cunning phishing onslaught, culminating in a staggering loss of 23,095,489 USD in stETH and rETH tokens. Coindroplet.io, a deceptive platform masquerading with alluring fake airdrops, ensnared an unsuspecting victim. Lured into the trap, this individual inadvertently signed a perilous transaction invoking the increaseAllowance() function. The malefactor swiftly orchestrated two transactions, siphoning off 9,579.21 stETH and 4,850.98 rETH to their domain. These ill-gotten gains were promptly converted to native ETH and DAI, maneuvered through a series of EOA addresses, with a portion funneled into TornadoCash. It’s imperative to note that the assailant’s address has ties to multiple dubious platforms, including coindroplet.io and coindroplet.net.

HTX Global $7.900.000

Huobi Global’s HTX crypto exchange encountered a security breach on Sept. 24, with a staggering $7.9 million in crypto assets compromised. Notably, the exchange claims to have identified the attacker. In a strategic move, Huobi offered the perpetrator a 5% “white-hat bonus” if they returned 95% of the stolen funds. The incident was confirmed by Huobi Global investor Justin Sun, who reassured that user funds remain secure and the platform is now fully operational. As the crypto world evolves, such incidents emphasize the importance of heightened security and vigilance.

Remitano $2.700.000

In a concerning trend for September, Remitano became the latest exchange to face a security breach, losing $2.7M from its hot wallets across Ethereum and Tron chains. The attack, suspected to be a result of a private key compromise, saw a swift response from Tether, which froze assets, reducing the potential loss from $2.7M to a mere $260k. While the exact method of the breach remains undisclosed, Remitano attributed it to a data leak from a third-party source. As the crypto landscape evolves, such incidents emphasize the importance of robust security measures and swift responses to mitigate potential damages.

Balancer $240.000

Balancer, a multi-chain AMM-based DEX, grappled with a frontend vulnerability exploit. This breach led to a significant depletion of 238,000 USD. The assailant, showcasing adept maneuvering, channeled the purloined assets via the bridge connecting the Avalanche and Ethereum ecosystems. Portions of the stolen wealth were also dispersed across multiple wallets. Notably, an attacker-associated address, 0xf998, was credited with 1.04 AVAX from MEXC.

Smart Contract Vulnerabilities

GMBL Computer $770.000

On September 5, 2023, the DeFi arena witnessed a shrewd exploit targeting GMBL Computer, a distinguished DeFi Gambling Protocol on the Arbitrum network. The malefactor ingeniously manipulated the project’s referral mechanism. Exploiting a loophole, they orchestrated “Ghost” wagers, which, while appearing as losses, paved the way for claiming 5% from these illusory bet losses. The assailant, using a strategic tandem of accounts, placed substantial “Ghost” stakes, enabling the secondary account to amass over 8 million $GMBL in referral rewards before halting the exploit. The ill-gotten assets were promptly exchanged for ETH and rerouted to a different EOA. In a surprising turn, 235.5 ETH of the pilfered 471.33 ETH was subsequently returned.

Boost Coin $600.000

On Sep 06, 2023, Boost Coin, a distinguished ERC20 token, fell victim to a calculated exit scam. The orchestrator behind the token exploited a privileged function, withdrawETH, to siphon off liquidity straight from the token’s core contract. A staggering 363.4 ETH, equivalent to roughly 593,267 USD at prevailing market valuations, was extracted. These pilfered assets journeyed through a maze of EOA addresses, ultimately finding refuge in KuCoin.

Conclusion

In the month of September, the crypto community faced a series of disconcerting security breaches, leading to significant financial repercussions. The incidents underscored vulnerabilities ranging from cloud service flaws to frontend exploits and even sophisticated phishing schemes. Platforms like Mixin Network, Huobi Global, and Balancer were among those that experienced these breaches, emphasizing the multifaceted nature of threats in the crypto space.

Prominent strategies employed by attackers included exploiting cloud service vulnerabilities, manipulating frontend systems, and orchestrating phishing attacks. The incidents involving CoinEx, Stake.com, and Boost Coin further highlighted the risks associated with private hot wallets and the phenomenon of rug pulls.

The events of September underscore the critical importance of stringent security protocols, regular audits, and continuous vigilance. As the crypto ecosystem continues to expand and evolve, these incidents serve as a potent reminder of the ever-present challenges and the imperative to fortify defenses against the myriad of threats in the dynamic world of cryptocurrency.

Follow HashEx DeFi Intelligence Ecosystem:
Announcement Channel
Twitter

Scam Report: September 2023 was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Scam Report: July 2023

Polly Traore — Tue, 08 Aug 2023 10:48:39 GMT

During the challenging month of July, the crypto world witnessed the notorious Multichain case, making headlines. However, it was not the only attack as significant losses were also incurred from rug pulls and code vulnerabilities.

To categorize the attacks, we split them into two groups: technical and non-technical. Smart contract vulnerabilities and oracle manipulations fall under the technical category, while exitscams and rug pulls belong to the non-technical category.

Top Tech Attacks

Multichain 2 $231.000.000

On July 10, 2023, the Multichain project experienced a significant exploit incident, which resulted in unauthorized access to the system and led to a substantial loss of funds across various chains. The attacker was able to transfer the funds to a single EOA (Externally Owned Account) in nine different chains. Interestingly, the transfer behavior indicated that the attacker had control over all the assets and was not in a hurry to move them, raising suspicions that the incident could have resulted from an internal operation within the project. The incident has raised concerns about the security of the Multichain project and highlights the importance of robust security measures to protect against such attacks in the crypto space.

Curve Finance $47.000.000

Some versions of the Vyper compiler lack proper implementation of the reentrancy guard, making contracts vulnerable to reentrancy attacks that can drain all funds. Several DeFi projects, including Ellipsis and Alchemix, were affected, resulting in millions of dollars in losses. Curving Finance CEO confirmed over $22 million worth of CRV tokens were drained from the swap pool.

AlphaPo $22.800.000

AlphaPo, a crypto payment platform used by various gambling services, fell victim to a security breach through a private key compromise. The exploit resulted in a loss of around $23M across Bitcoin, Tron, and Ethereum chains. The stolen assets were converted to 5,742 ETH, which was then bridged to Avalanche and swapped for BTC before being transferred to the Bitcoin chain.

Poly Network 2 $10.200.000

The Poly Network experienced a sophisticated attack through access control, allowing the exploiter to generate signatures using the project’s wallets and drain significant amounts of assets across multiple chains, including Ethereum, Binance Smart Chain, Avalance, and Metis. After the initial attack, the exploiter conducted two more attacks, swapping a large amount of $SHIB and other liquid assets for ETH and draining $USDC and $USDT. In total, the attack resulted in the theft of 5,196.95 $ETH, valued at around $10,201,612 USD. The stolen assets also included non-liquid ERC20 tokens, with the total stolen assets across several chains being even higher than the actual funds lost. However, due to low liquidity, the attackers were unable to cash out. As a precaution, 18,444,696 $USD worth of tokens were distributed to 17 EOA addresses, along with 1 $ETH each, to potentially prevent further exploitation.

EraLend $3.400.000

EraLend, a lending protocol on zkSync Era, recently experienced a devastating exploit in the form of a read-only reentrancy attack. As a result of this attack, the protocol suffered a substantial loss of approximately 3,400,000 $USD. The root cause of the exploit has been identified as a vulnerability in the protocol’s code, which allowed the attacker to execute multiple functions in quick succession, leading to the draining of funds from the platform.

Conic Finance $3.250.000

Conic Finance on Ethereum experienced an exploit due to a reentrancy issue, leading to a loss of 3,254,850 $USD. The attack was a result of a wrong assumption about the address returned by the Curve Meta Registry for ETH in Curve V2 pools. The attackers stole 1,724 $ETH, equivalent to approximately 3,254,850 $USD, and transferred them to another EOA. Despite an unsuccessful attack attempt 10 minutes prior, the exploit was successful, marked as read-only reentrancy. Conic has taken action by reaching out to the exploiter through a transaction from the official Conic Multisig address.

Top Non-Tech Attacks

Bald $23.100.000

Bald, an ERC20 token on Coinbase’s Base chain and LeetSwap, experienced an exit scam by its deployer who removed liquidity from the LP pool in multiple transactions. The scam resulted in the theft of 10,804 $ETH, valued at approximately $19,930,848 USD. As of July 31, 2023, the scammer still holds the stolen funds, now totaling 12,059 $ETH, equivalent to $22,458,422 USD. The project’s official tweet claims that no tokens were sold, only liquidity added and removed.

GMETA $3.670.000

In a rugpull incident, GMETA, a BEP20 token, suffered losses. The token deployer transferred a substantial amount of $GMETA tokens to an EOA address on February 4, 2023. Some tokens were moved to another EOA and sold, draining over 2.3 million $USDT from the PancakePool. The remaining tokens were transferred between multiple EOA addresses, and one of them drained the pool for an additional 1.3 million $USDT, with 1 million $USDT going to an unverified contract.

Hayden Adams Phishing $3.600.000

The Twitter account of Hayden Adams was exploited by scammers who have been active since April 2023. These cyber criminals created over 23 phishing sites over the course of several months, targeting unsuspecting users. Through these fraudulent sites, they managed to steal approximately 3,600,000 $USD from around 358 victims. The phishing scam involved tricking users into sharing sensitive information, which then led to a significant loss of funds. One victim suffered the most significant loss, totaling 2,280,000 $USD, stolen through an ERC20 Permit phishing technique.

DefiLabs $1.630.000

DefiLabs Farm, a staking platform on the Binance Smart Chain, was hit by an exitscam. The vPoolv6 contract’s deployer set a new privileged address ‘funder’, which then withdrew funds using the ‘withdrawFunds’ function and transferred them to another EOA. The assets exploited included USDT, BTC, ETH, and CAKE tokens, resulting in an estimated loss of 1,634,351 $USD.

Conclusion

In July, a total of 46 incidents were reported in the crypto space, resulting in a staggering loss of approximately $303 million. The report highlights that the majority of these attacks exploited code vulnerabilities, with hackers meticulously planning their moves several weeks in advance. Among the common tactics used were reentrancy attacks and flash-loan token price manipulation.

Notably, classical hacks such as compromising private hot wallets and rug pulls also persisted, indicating that attackers are constantly finding new ways to exploit weaknesses in the system. The prevalence of rug pulls in particular highlights the need for decentralized project architecture, as audits often reveal centralization issues that can leave projects vulnerable to such attacks.

Overall, the report serves as a stark reminder of the importance of robust security measures and the need for continuous monitoring and auditing to protect against potential threats in the ever-evolving crypto landscape.

HashEx website: https://hashex.org
Request an audit

Scam Report: July 2023 was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Scam Report: June 2023

Polly Traore — Thu, 13 Jul 2023 16:20:41 GMT

For the crypto community, the past month brought its share of challenges, including the notorious Atomic Wallet case. And it wasn’t the only attack, significant losses followed multiple rug pulls and errors in code.

Top Tech Attacks

Atlantis Loans $1,250,000

Atlantis Loans, a BSC eco-protocol, is currently facing a governance attack that has resulted in a loss of over $1 million. The attackers took control of the contract and replaced it with a modified version containing a backdoor to transfer user assets. The malicious governance proposal was introduced on June 7, 2023, through the GovernorBravo contract.
Source

Sturdy Finance $780,000

Sturdy Finance fell victim to an oracle price manipulation attack. Through a read-only reentrancy attack, the attacker exploited the SturdyOracle contract and manipulated its pricing. They withdrew funds from the ‘Sturdy_eth interest bearing WETH’ contract, resulting in a loss of $880,850. The attacker made a profit of 442 ETH (approximately $775,332) and used the remaining funds as a flashloan commission. The illicit profits were subsequently moved through TornadoCash in multiple transactions.
Source

Midas Capital $600,000

The Midas Capital, a lending platform on the Binance Smart Chain, fell victim to an exploit caused by a flaw in one of its contracts. The attacker took advantage of this vulnerability to siphon off more than $600,000 worth of stablecoins and BNB tokens. To cover their tracks, a portion of the stolen funds was converted to 510 BNB and transferred using TornadoCash. A flaw in the contract allowed the attacker to exploit the redeem counter, resulting in multiple times the value of the HAY/BUSD AMM tokens. This incident highlights the importance of thorough code review and verification in preventing such exploits.

Themis Protocol $370,000

Themis Protocol, a lending protocol built on Arbitrum, experienced a flash loan attack. By deploying a malicious contract, the attacker exploited various pools of the protocol, including tArbWETH, tArbUSDC, tArbARB, tArbWBTC, tArbDAI, and tArbUSDT. The stolen assets were converted to ETH, USDT, and USDC in a single transaction. Manipulating prices, the attacker acquired 94.32 ETH ($178,453), 130,471 USDC, and 58,824 USDT, totaling $367,748. The stolen funds were then transferred to the Ethereum Mainnet via a bridge and passed through TornadoCash.
Source

Ara Blocks $125,000

Ara Blocks, an NFT project on the Binance Smart Chain, experienced a flashloan attack, leading to a loss of $124,915. The attacker successfully exploited the project and transferred the stolen funds to another externally owned account (EOA) that now holds all the assets.
Source

Top Non-Tech Attacks

USEA $1,100,000

USEA Token, a BEP20 token available on PancakeSwap, fell victim to a major rugpull. The individual responsible for deploying the token minted a staggering 867 million USEA tokens and transferred them to a different EOA address. The scammer proceeded to sell off the entire token supply for approximately $1,114,468 on PancakeSwapV3. Further investigation unveiled that the stolen funds were dispersed to various other addresses.

Chibi Finance $1,000,000

Chibi Finance, a yield farming protocol on Arbitrum, experienced a malicious attack on June 27, 2023. The attacker exploited a privileged function to set a malicious contract as the Governance contract and proceeded to drain assets from three contracts: StrategyAave, StrategySushiSwap, and StrategyGHA. The stolen assets included WBTC, USDC, WETH, USDT, and SLP tokens, totaling $1,052,646 in value. The stolen funds were converted to WETH and bridged using Multichain and Stargate. Following the incident, the project’s website was shut down and the Twitter account was deleted.

VPANDAO DAO $870,000

A mysterious exploiter orchestrated an exit scam within the VPANDA DAO, a BEP20 token project on Binance Smart Chain. The scam involved transferring a large number of VPANDA tokens to a contract called VpandaBank, whose ownership was then transferred to the alleged scammer. The scammer exploited a privileged function in VpandaBank called ‘withdraw’ to transfer a significant amount of VPANDA tokens and drain liquidity from PancakePool. The funds lost in this scam amounted to $869,463.

EthBread Token $790,000

ETB, a token on Binance Smart Chain, faced a notable liquidity reduction on PancakeSwap. On February 16, 2023, ETB tokens were distributed to various addresses, followed by a significant liquidity drain on June 25, 2023. Addresses linked to the deployer collectively withdrew around $786,574 from the ETB/USDT pool. Additionally, one directly associated address removed liquidity worth $135,291.

Pawnfi $630,000

An incident involving APE (ApeCoin) and APE Staking resulted in a significant gain of over 630K. Multiple Pawnfi contracts, including ApeStaking, were exploited, resulting in a total loss of funds worth 633,441 $USD, equivalent to 366.77 ETH. The attacker used TornadoCash to transfer 100 ETH and moved the remaining 266.77 ETH to another EOA address, where the stolen funds are currently held.

Unidentified Attacks

Atomic Wallet $35,000,000

Currently, it is unclear whether the attack falls under non-tech or tech-related attacks, and further investigation is underway.

Several Atomic Wallet users reported stolen assets on June 3. Atomic Wallet stated that less than 1% of their monthly active users were affected. In response to the incident, Atomic Wallet took emergency measures by disabling Cloudflare’s download site and the sha256sum verification site. According to some users, the security issue may still remain in the download link for older versions.

Conclusion

In June, the crypto community encountered 38 incidents resulting in a loss of approx. $79,900,000.

This report highlights that major attacks primarily exploit code vulnerabilities, with hackers taking weeks to prepare for an attack. Common trends include susceptibility to reentrancy attacks and flash-loan token price manipulation. Classical hacks, such as compromising private hot wallets and rug pulls, also persist.

The prevalence of rug pulls emphasizes the need for decentralized project architecture. Our audits frequently uncover centralization issues, and the significant amount of rug-pulled funds reinforces the concern. Due to the limited regulation in the crypto space, it can be challenging to take legal action against teams conducting rug pulls. Consequently, the responsibility to mitigate the risk of rug pulls lies with the smart contract logic.

HashEx website: https://hashex.org
Request an audit

Scam Report: June 2023 was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Top zk-rollups to watch in 2023–2024

Polly Traore — Wed, 07 Jun 2023 15:53:13 GMT

The dawn of zk-rollups

The year is 2023. For a long time, developers have been trying to solve the blockchain trilemma of scalability-security-decentralization. A number of new Ethereum layer-2 solutions or rollups are emerging in order to take on that task. Many of them are zk-rollups, meaning they are based on zero-knowledge proofs (more theory on SNARKs and STARKs here). The benefits are scalability, privacy, and security, while the problem is that they are difficult to build.

According to Vitalik Buterin, zk-rollups will eventually outperform optimistic rollups (e.g. Arbitrum, Optimism) and win the scaling layer-2 war. With years already in the making, it looks like the time has finally come and we are about to witness a new era of Ethereum. We can verify this by looking at the constant increase in TVL in L2 solutions. In the past 2 years, we have seen the rise and flourishing of optimistic layer 2s, the importance of which I by no means want to downplay in this article. In the next 2 years, we can expect a similar story for zero-knowledge (or validity) rollups. Are you excited yet? Let’s dive into it.

zkSync Era

After launching zkSync Lite in 2020 and successfully developing it, Matter Labs launched zkSync Era mainnet in March 2023. Unlike Lite it is a zkEVM rollup that allows developers to use tested code and apply years of experience of working with Solidity. SNARK technology was chosen For zk-proofs over STARK due to its speed and computational power requirements.

Era’s ecosystem is constantly growing. It already includes over 50 projects of all kinds: from infrastructure and wallets to defi and games. zkSync has partnered with BitDAO, one of the biggest DAOs out there. It will be governed by zkDAO which aims to promote growth in its ecosystem by incentivizing projects and initiatives.

One of the zkSync features currently in development is Account Abstraction. It’s expected to allow web2 user onboarding with well-known “social login” systems, e.g. login/password or email.

Here, an in-depth article on zkSync is available for those seeking.

StarkNet

Starknet is a permissionless decentralized zk-rollup. Developed by Starkware, it has been live since late 2021, however, it is not EVM-compatible.

Starknet is based on the Cairo programming language, which is optimized for zk-proofs. To enable smart contracts & composability, StarkNet takes a language-level compatibility approach & transpiles EVM-friendly languages (e.g. Solidity) down to a STARK-friendly VM (in Cairo).

The chain is also developing kits for Account Abstraction which will reduce the onboarding complexity for users and can be considered one of the main mass adoption tools.

There are more than 70 applications running on the mainnet today, and many more are moving towards it at full throttle.

Starknet’s current development primary focus is on performance and UX. As stated in their roadmap for 2023, we can expect fee and latency reduction as well as throughput improvements later this year.

Scroll

Scroll is a classic zkEVM rollup currently in the Alpha Testnet phase. It went live in February on Goerli network. The team behind Scroll prioritizes EVM equivalence and a community-oriented approach. Indeed, there are community-friendly deeds on their list such as sharing found vulnerabilities with Aztec and Linea or hosting a ZK Symposium that helped boost the discussion about the cutting-edge technology in rollup space.

From a technological point of view, Scroll rivals Polygon zkEVM as they have a similar bytecode-level approach. However, the former can be considered more EVM-compatible than the latter.

The ecosystem already consists of more than 30 projects and is growing steadily. Scroll has its own security team, which assists in keeping the code correct and up-to-date. An in-depth review is available on one of the co-founders’, Ye Zhang’s HackMD page.

Linea

ConsenSys, the team that created Metamask, is building a zkEVM rollup. The testnet was released on March 28 and is live now.

As a rollup Linea is being built with a developer-centric approach. In order to reach it, zk-proofs are combined with full EVM-equivalence, allowing developers to create scalable dApps or migrate existing ones seamlessly. The ecosystem already numbers more than 30 applications of all different kinds.

There is an ongoing voyage campaign that aims at stress-testing the current testnet version. Another goal of this voyage is to support Linea’s mainnet release later this summer. Everyone is welcome to participate using Goerli ETH which can be claimed at certain faucets for free. Users are rewarded for completing challenges via a series of Linea NFTs.

Polygon zkEVM

As stated in the documentation, Polygon zkEVM is a decentralized Ethereum Layer 2 scalability solution that absorbed Mir and Hermez rollup as well as its earlier developments. The project has been under development since mid-2022 and the Mainnet Beta launched on March 27. As of today, there are less than 20 dapps in its ecosystem. It is important to remember that it’s using ETH for gas and not MATIC.

Not being fully EMV-compatible, but with a high degree of EVM equivalence in Polygon, zkEVM provides developers and users with an experience similar to using Ethereum mainnet, though with much more privacy, speed, and at a lower cost.

One of the unique features of this rollup is a novel consensus mechanism called Proof-of-Efficiency (PoE) which was designed to address the challenges of sequencer decentralization.

Here is another more in-depth article, this time on Polygon zkEVM.

Taiko

The project was founded in early 2022 by a group of well-known developers some of whom have experience working with zk-rollups at Loopring.

Taiko is aimed for maximum compatibility with EVM, it can even be said that Taiko is an equivalent of Ethereum. This offers a lot of benefits to developers, for example, they can seamlessly migrate smart contracts and dApps to Taiko. However, pursuing such a degree of compatibility comes with disadvantages, the main one being slow zk-proof generation speed. They aim to overcome it by means of parallel proof verification for different blocks on L2.

Taiko is an open-source rollup and the code is available on the project’s github.

Here, a more detailed overview of Taiko is available.

Aztec

Following the shutdown of their zk.money project, the Aztec team decided to pivot to creating its own hybrid zk-rollup for Ethereum. Aztec uses Noir zk programming language for its smart contracts. Therefore, it’s not EVM-compatible nor is it a zkEVM blockchain. The idea behind “hybrid” is to enable both public and private smart contract execution. In many ways it resembles StarkNet with one major difference: Aztec prioritizes encryption and privacy.

The project is in early development, so a Bug Bounty program is available. Its goal is to achieve the code’s safety. The team has also included a grant program for developers in order to attract new projects to the ecosystem.

You can find more detailed info about Aztec and its features on zero-knowledge future in the project’s Medium.

Follow HashEx DeFi Intelligence Ecosystem:
Announcement Channel
Twitter

Top zk-rollups to watch in 2023–2024 was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Auditing Blockchain

Polly Traore — Tue, 25 Apr 2023 10:29:02 GMT

The popularization of Web 3.0 gave way to various blockchains, each containing a plethora of apps. While we are mostly used to discussing blockchain in the context of finances, it’s not the only use of the technology. In fact, blockchains have proved useful in nearly every area of life.

However, all the celebrated achievements of Web 3.0 unavoidably go hand in hand with security risks. It’s blockchain, decentralized finances, to be more specific, that sees the majority of large monetary losses. That’s why today we look at the importance of auditing blockchains.

What is a Blockchain Audit?

More often we hear or rather, deal with smart contract audits. Why? It’s a simple matter of numbers: while smart contacts are many, blockchains are a few. Off the top of one’s head, an average user may be able to name no more than 10–15. That’s why blockchain audits, unlike smart contract or DApp audits, are less common. Regardless, every blockchain absolutely has to go through the scrutiny of an audit.

Blockchain audit is a process, during which security experts review the potential vulnerabilities and errors that can cause malfunctions in the blockchain.

How Does it Work

A blockchain audit, like any other audit, consists of several crucial steps. The team has to review the code of the chain, the data stored in it, and its technical specs. In other words, this is a more complex process than auditing a DApp.

The first step is for the team to assess the work ahead, and to understand and review the architecture behind the blockchain. At this point, auditors have to get a full image of what’s expected of the chain and how it is supposed to function. Only then auditors can get to the next part of the task.

After the initial evaluation, comes a more detailed manual review. Here, the auditors would normally check the integrity of every function in the code. Errors are corrected and recommendations on ways to fix them are written down. The code is also tested using various techniques.

Compiling a review is the final step of an audit. The discovered issues are listed with full descriptions and recommendations for the owners of the chain to review. After that, the corrections are made and the follow-up procedure takes place. The final review provides a complete list of issues and corrections along with recommendations. This version is usually available to the public and guided by this document users can actually evaluate the possibilities and potential risks of working with a specific chain.

Why Should Blockchains be Audited

The ultimate goal of any audit is to detect the issues that may result in malfunctions. In that sense, an audit is a guarantee that the code is functional, reviewed, and safe to use. But that’s not the only reason why a blockchain should be audited.

Owners of a blockchain have to consider that it’s likely for users to be working with finances which means any loss due to an error in the blockchain will affect users not just in terms of convenience.

To avoid such issues, industry standards, such as GDPR and FATF, have been put up. Again, they mostly concern the financial aspect of chains, however, it’s necessary to follow them.

An audit can point out ways to improve the overall functioning of certain features. For instance, auditors provide recommendations on code readability and quality.

Taking all the available security measures prior to launching a blockchain is a necessity. Releasing an unstable product can result in financial and reputational losses. Both types are hard to recover from. When choosing an auditor for a blockchain, owners should select the most reputable and experienced auditors to guarantee that the potential issues would be fully discovered.

Auditing Blockchain was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Why Get a Security Subscription?

Polly Traore — Mon, 20 Mar 2023 10:40:25 GMT

Once a smart contract is finished, an audit is completed, and the project is released, many would assume the job is done and it’s time to kick back, relax, and watch the marketing team do their magic while the project gets its recognition. That’s what we’d like to see happen but, alas, that isn’t the reality behind the work of a developer.

Once Audited, Always Secure

Despite a smart contract audit being a proper way to ensure that the project isn’t vulnerable to attacks and that all features work as intended, it only covers the first committed version. Byt no project remains unchanged. Eventually, there are going to be security adjustments, updates, new features, and so on. Every change to the code may affect more than just a specific feature. This is why aside from the first security audit, projects may require regular maintenance.

Still, we have to admit that developers do not always possess the knowledge and skill required to review the code and correct existing errors in it.

Why a Code Has to be Rechecked

An often-ignored fact is that Each new string of code might affect not just the function it sets up, but the whole repository. Which is especially relevant when we’re talking about a forked project, where changes to the original code aren’t always properly audited in relation to the rest.

Meanwhile, when it comes to smart contracts, errors can cause financial losses, not just to the project, but to its clients. Needless to mention that such cases always reflect poorly on the company and its owners.

There are simpler codes and there are complicated systems that require multiple different types of code. Such cases more than anything require maintenance, especially when you consider that it’s impossible to change a code after its deployment. Whenever developers add new features or adjust existing ones, a recheck has to be made. It’s a job that’s better left to professionals since it’s preferable to have auditing knowledge and proper testing methods at hand.

How to Maintain the Repository?

HashEx offers a Security Subscription service. By subscribing to this service, our customers gain access to the assistance of an experienced and skillful team of security specialists. Every time the project team requires reviews of their newly written code, the HashEx team will respond to their needs. This is an easy way for any project, big or small, to guarantee the security of its code.

HashEx auditors have vast experience with multiple chains and smart contract languages as well as various projects.

If you need to make sure that your chain, marketplace, or any other type of project, is safe to use and the updates you make don’t affect its functionality or raise any security issues, then HashEx Security Subscription is the way to go.

Why Get a Security Subscription? was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Timelock: Achieving Security for Decentralized Projects

Polly Traore — Tue, 28 Feb 2023 20:37:25 GMT

Centralization issues are among the most common ones you may encounter while dealing with Smart Contracts. The majority of the contracts we audit leave users with the need to trust the project owner. And many indeed consider it the necessary evil of the DeFi fiat world. You are expected to rely on the decisions of a third person, often anonymous. But do you have to?

Trusting an Anonymous

A genuinely decentralized project is a bit more complicated than a centralized one, it’s harder to build, sure, but easier to promote to the community. When we say that blockchains are built on trust, it’s true. Yet the main issue with said trust is that anonymous projects do not have to pass any security checks or audits. They don’t require accreditation to function which supposedly leaves you trusting the owners blindly but the reality is a bit different. Keep in mind, that when we consider people and/or organizations, blockchain does not rely on trust.

A lack of regulation doesn’t necessarily mean a Wild West type of situation where everyone makes up their own rules. Instead, it demands self-regulation, which in a futuristic environment such as blockchain has to be fairly strict.

Indeed, there are measures that help regulate a decentralized project, lowering the risks that accompany it. Some of the most common examples are using a DAO for governance and using a multisig wallet of independent participants. But arguably, the most promising is a timelock contract.

Timelocks and how they work

Timelock contracts can help lower the possibility of an attack on private wallets.

What these contracts do is provide a delayed transaction. This explains their name, which comes from a specific contract feature that guarantees that the contract can only be fulfilled within a specific previously set time frame.

For any transaction to pass, it has to be first announced, so that it becomes visible to all the network participants. As it has been established, this transaction can be passed after a specific amount of time has passed.

For instance, we take a 24-hour TimeLock in the contract. That means there’s a 24-hour window between the transaction’s creation and the moment it is mined to the network. If the transaction is seemingly risky, say, the owner is attempting a rug pull, the users have 24 hours to pull their funds.

Obviously, this measure secures users’ funds, giving them authority and time to take action. Something that was previously inaccessible to them. The possibility of taking preventive action, in this case, is aimed at giving users confidence in a project. They still have control over their money instead of being left at the mercy of the contract owner.

Timelock makes a privileged account far less interesting for attackers.

Applications of Timelock contracts

TimeLock Smart contracts can be used in several instances.

In most cases, Timelock is used in projects with privileged contracts where the owner has technical opportunities to either rug pull or break the protocol. In a smart contract, the owner of the privileged role is Timelock. And the owner of the Timelock is usually set to a Multisig wallet or DAO.

This technology is also widely used to block the funds transferred from investors. This simplifies monitoring of the spending and makes a project more attractive for potential investors as well as users.

A good example of Timelock contracts application is SushiSwap and Compound. Both use timelocks for delaying admin operations in their protocols. We, at HashEx, successfully develop timelock contracts and offer other development and security services.

Follow HashEx DeFi Intelligence Ecosystem:
Announcement Channel
Twitter

Timelock: Achieving Security for Decentralized Projects was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Avana Smart Contracts Audit Report

Polly Traore — Mon, 13 Feb 2023 13:44:29 GMT

HashEx was commissioned by the AVANA team to perform an audit of their smart contract. The audit was conducted between 2023–01–18 and 2023–01–18.

The purpose of this audit was to achieve the following:
• Identify potential security issues with smart contracts
• Formally check the logic behind given smart contracts.

Information in this report should be used for understanding the risk exposure of smart contracts, and as a guide to improving the security posture of smart contracts by remediating the issues that were identified.

The code is available at 0xf84C55e79858B448c3015c3a1A55efED9EdF69c7 in the Binance Smart Chain (BSC) network.

Contract

CoinToken

An implementation of the ERC-20 token standard made with slightly modified OpenZeppelin contracts.

Issues

#01. Import of OpenZeppelin contracts

Severity: Info
Status: Open

We recommend importing contracts from the OpenZeppelin library without modifying them. Any additional functionality may be introduced via overriding since all OpenZeppelin contracts support it.

Contract

ERC20

Modified version of OpenZeppelin’s implementation of ERC-20 token with removed _beforeTokenTransfer() and _afterTokenTransfer() transfer hooks, overridden decimals() function and modified constructor.

Issues

#01. Incorrect decimals type

Severity: Low
Status: Open

The ERC20 standard states that the decimals() function of a token should return uint8. Instead, a uint256 value is returned.

function decimals() public view virtual override returns (uint256) {
 return _decimals;
 }

#02. Gas optimizations

Severity: Low
Status: Open

Since the ERC0 contract is not imported from OpenZeppelin directly, a few gas optimizations could be implemented:

The variables _decimals, _name, and _symbol should be declared immutable.
The name(), symbol(), decimals(), totalSupply(), balanceOf(), allowance(), approve(), increaseAllowance(), decreaseAllowance(), transfer(), and transferFrom() functions should have external visibility.

#03. Irrelevant comments

Severity: Info
Status: Open

The NatSpec description of the constructor section should be reworked since it’s inherited from OpenZeppelin’s ERC20 contract but the constructor’s contents were modified making the description semi-irrelevant.

#04. Typos

Severity: Info
Status: Open

Typos reduce the code’s readability. Typo in ‘defaut’.

Conclusion

2 low severity issues were found during the audit. No issues were resolved in the update.

HashEx website: https://hashex.org
Request an audit

Avana Smart Contracts Audit Report was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

Polarys Smart Contracts Audit Report

Polly Traore — Tue, 31 Jan 2023 09:49:20 GMT

HashEx was commissioned by the PolarysDAC team to perform an audit of their smart contract. The audit was conducted between 02/01/2023 and 05/01/2023.

The purpose of this audit was to achieve the following:

Identify potential security issues with smart contracts
Formally check the logic behind given smart contracts.

The code is available in the @PolarysDAC/polarys-contracts public GitHub repository after the commit 6b61a36.

Update. The PolarysDAC team has responded to this report, the updated code is located in the same repository after dcdedc7 commit. The audited PolarDepositContract was deployed at the Ethereum chain at address 0x061Bb29F047472eEF713B994c7320eF95E1f86aA, TokenVesting contract was deployed to Metis Andromeda chain at address 0x64DdED4Bf12656326f3d0a40F00f973409Fea3d4.

Contract

PolarDepositContract

The contract allows depositing ERC20 tokens with specifying the quantity of NFT tokens. Only users with the Deposit role and with a special signature can make a deposit. Such signatures are provided by third-party applications.

Users who have admin permission can withdraw deposited ERC20 tokens to any address.

According to the developer, the contract allows accepting payment for NFT in other chains. After payment, the contract emits events that must be processed by third-party applications. Based on these events, users will be able to receive NFT tokens on other networks.

At the same time, the audit team did not audit third-party applications.

Issues

#01. Gas optimization

Severity: Low
Status: Resolved

The state variable priceFeed can be declared as immutable to save gas.

#02. Constructor lacks validation of input parameters

Severity: Low
Status: Resolved

The contract constructor does not validate the values of the acceptToken and priceAggregator variables against non-zero value.

#03. Reentrancy guard

Severity: Info
Status: Resolved

Since the audit team does not know the _acceptToken token, we recommend adding a nonReenrant modifier for the depositToken() function to prevent potential threats associated with callbacks inside the _acceptToken token.

#04. Lack of documentation (NatSpec)

Severity: Info
Status: Partially Fixed

We recommend writing documentation using NatSpec Format for the depositNativeToken() function and for all parameters of the depositToken() function. This would help in development, as well as simplify user interaction with the contract (including using the block explorer).

#05. Price calculation

Severity: Info
Status: Acknowledged

The depositNativeToken() function calculates the quantity of tokens that will be minted on another network.
According to the current formula, the cost of one token will be about 25000000wei = 0.000000000025 ether (or 1.2usd = 48003585 tokens at the exchange rate on January 02, 2023).
Please make sure the calculation is correct and add tests.
In addition, the depositNativeToken() function does not involve paying change if the user's transferred funds were not a multiple of the value of the tokens.

Contract

TokenVesting

The contract is used to distribute (vest) tokens to certain users.

Contract admins with VESTING_ROLE can create and revoke PolarysToken vestings for any user. The admin can revoke vesting at any time. At the same time, tokens for which the release time has not yet come will be returned to the owner of the contract (to an address controlled by him).

Issues

#01. Zero-containing vesting

Severity: Critical
Status: Resolved

The vesting plan can contain zero values for several months (not for the first period). In this case, users who decide to withdraw their tokens in a month with a zero value will not be able to do this, or they will be able to withdraw tokens that do not belong to them.
Case 1.
For example, the vesting plan is as follows [2000, 6000, 0, 0, 0, 0, 1000, 1000]. If the user has not withdrawn the tokens in the first two months, he will be blocked for the next four months due to zero values and the if condition (L296–298) in the _computeReleasableAmount() function.

 function _computeReleasableAmount(VestingSchedule memory vestingSchedule)
 internal
 view
 returns (uint256)
 {
 unchecked {
 uint256 currentTime = block.timestamp;
 uint256 vestedAmountByDefault = vestingSchedule.immediateVestedAmount — vestingSchedule.released;
 if (vestingSchedule.startTimestamp > currentTime) { // vesting is not started yet
 return vestedAmountByDefault;
 }
 uint256 monthCount = ((currentTime — vestingSchedule.startTimestamp) / 30 days) + 1;
 uint256[] memory monthUnlockPercentList = _monthUnlockPercentSchedules[vestingSchedule.vestingGroupId];
 if (monthCount > monthUnlockPercentList.length) { // vesting period is ended
 return vestingSchedule.amountTotal + vestedAmountByDefault;
 }
uint256 unlockPercent = monthUnlockPercentList[monthCount-1];
 if (unlockPercent == 0) { // cliff period
 return vestedAmountByDefault;
 }
 
 // vesting period
 uint256 totalPercents;
 for (uint256 index; index < monthCount; ++ index) {
 totalPercents = totalPercents + monthUnlockPercentList[index];
 }
 uint256 vestedAmount = vestingSchedule.amountTotal * totalPercents / 10000; 
 vestedAmount = vestedAmount + vestedAmountByDefault;
 return vestedAmount;
 }
 }

Case 2.
For example, the vesting plan is as follows [2000, 6000, 0, 0, 0, 0, 1000, 1000], the immediateVestedAmount is zero (or less than the first vested amount) and amountTotal is 10000 tokens.
The user withdrew funds in the first period and now vestingSchedule.released is 2000. After that, the user waits for a period with zero distribution (for example 4th period) and calls the release() function with the argument amount=polarysToken.balanceOf(address(TokenVesting)). The calculation on L285 will return an underflowed result for the release() function. Thus, the contract balance will be transferred to the user's address.

function release(bytes32 vestingScheduleId, uint256 amount)
 public
 nonReentrant
 {
 VestingSchedule storage vestingSchedule = vestingSchedules[vestingScheduleId];
 require(vestingSchedule.beneficiary != address(0), “Invalid vestingScheduleId”);
 if (vestingSchedule.revoked)
 revert ScheduleRevoked();
 address beneficiary = vestingSchedule.beneficiary;
 bool isBeneficiary = msg.sender == beneficiary;
 bool isOwner = hasRole(VESTING_ROLE, msg.sender);
 if (!isBeneficiary && !isOwner) revert BeneficiaryOrOwner();
 uint256 releasableAmount = _computeReleasableAmount(vestingSchedule);
 if (releasableAmount < amount) revert NotEnoughTokens();
 vestingSchedule.released = vestingSchedule.released + amount;
 vestingSchedulesTotalAmount = vestingSchedulesTotalAmount — amount;
 polarysToken.safeTransfer(beneficiary, amount);
 emit Released(msg.sender, vestingScheduleId, amount, block.timestamp);
 }

Recommendation: 1. We strongly recommend avoiding the unchecked mode in the _computeReleasableAmount() function. This will reduce the risk of incorrect calculation of tokens.
2. The zero distribution periods processing architecture needs to be redesigned.

#02. Change of the vesting schedule

Severity: High
Status: Resolved

The contract admin with VESTING_ROLE can change any vesting schedule at any time using setUnlockMonthSchedule() since the admin can specify any value for the vestingGroupIndex parameter.
Thus already created and partially paid vestings can be changed. This can significantly affect the correctness (and honesty) of the calculation. In this case, some users will be able to receive more than 100% of the tokens (and some less than 100%).

Recommendation: Consider using a unique nonce counter for _monthUnlockPercentSchedules mapping.

#03. Constructor lacks validation of input parameters

Severity: Low
Status: Resolved

The contract constructor does not validate the values of the polarysToken and _owner variables against non-zero value.

#04. Check for 100% vesting

Severity: Low
Status: Resolved

The function setUnlockMonthSchedule() allows the creation of vesting plans with totalPercents value of less than 100%. At the same time, when creating vesting, the createVestingSchedule() function checks that the contract is provided with tokens in full (amountTotal + immediateReleaseAmount).
But if the vesting of totalPercents is less than 100%, then the amountTotal will be paid out in full only after the vesting time is completely over, even if the last periods have zero percentages. For example, for vesting month schedule [3000, 6000, 0, 0, 0, 0, 0] the user has to wait 7 months to receive 100% of the tokens.
This behavior is possible due to a non-strict check for totalPercents value in the setUnlockMonthSchedule() function.

function setUnlockMonthSchedule(uint256 vestingGroupIndex, uint256[] calldata monthUnlockPercentList) external onlyRole(VESTING_ROLE) {
        uint256[] memory monthPercentList = monthUnlockPercentList;
        uint256 monthCount = monthPercentList.length;
        uint256 totalPercents;
        for(uint256 i; i < monthCount; i = _unsafe_inc(i)) {
            unchecked {
                totalPercents = totalPercents + monthPercentList[i];
            }
            require(totalPercents <= 10000, "TotalPercent is limited to 100%"); 
        }
        ...
    }

function _computeReleasableAmount(VestingSchedule memory vestingSchedule)
 internal
 view
 returns (uint256)
 {
 unchecked {
 …
 uint256 vestedAmount = vestingSchedule.amountTotal * totalPercents / 10000; 
 vestedAmount = vestedAmount + vestedAmountByDefault;
 return vestedAmount;
 }
 }

Recommendation: We recommend updating the require statment for the totalPercents value in the setUnlockMonthSchedule() function (L108):

require(totalPercents == 10000, “TotalPercent is limited to 100%”);

#05. Gas optimization

Severity: Low
Status: Resolved

a. Remove the unused harhat/console.sol import on L8.
b. The variables startTimestamp and vestingGroupId of the VestingSchedule structure can be packed into one storage slot by casting to uint128.
c. No need to create a new variable monthPercentList on L101 with the same values as an input parameter of the setUnlockMonthSchedule() function.
d. No need to create a new variable vestingSchedule on L268 (and read again from storage) with the same value as the local variable memoryVestingSchedule in the computeReleasableAmount() function.

Conclusion

The contract PolarDepositContract is highly dependent on third-party applications. Users using the project have to trust the owner (as well as the project team) and be sure that the third-party applications work correctly and that vesting is created honestly.

We strongly suggest adding unit and functional tests.

This audit includes recommendations on improving the code and preventing potential attacks.

Note: no third-party application has been audited by the audit team.

HashEx website: https://hashex.org
Request an audit

Polarys Smart Contracts Audit Report was originally published in HashEx Security Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.

HashEx Blog

Sharing useful information about the blockchain

Let's Work Together! Write now.