zkSync Era is Matter Labs' ZK Rollup L2 on Ethereum. It uses zero-knowledge proofs to achieve finality while maintaining EVM compatibility (though not equivalence). zkSync hosts over $1.2 billion in TVL and represents the cutting edge of ZK scaling. FirePan monitors contracts deployed on zkSync, using adapted HOUND AI to detect EVM incompatibilities, access control failures, and bridge vulnerabilities. zkSync's unique position—using cryptographic proofs instead of fraud proofs or full Ethereum inheritance—introduces novel attack surfaces: opcodes behave subtly differently, and developers unfamiliar with ZK semantics can accidentally write code that behaves differently on zkSync than expected.
zkSync is fundamentally different from rollups like Optimism or Arbitrum. Instead of optimistic rollups (assume valid unless proven invalid), zkSync uses ZK proofs (cryptographically prove validity). This enables faster finality (no fraud proof window) and stronger security (proofs are deterministic). But it introduces complexity: not all EVM opcodes behave identically, some operations are more expensive, and contracts can behave differently on zkSync than on Ethereum.
Matter Labs designed zkSync to be "EVM compatible"—Solidity contracts compile and mostly work. But compatibility is not equivalence. Some low-level operations (raw storage access, certain opcodes) have different semantics. A contract might pass Ethereum's tests but fail on zkSync, or worse, behave differently (e.g., returning a different value for tx.origin).
zkSync's ecosystem is younger than Arbitrum or Optimism, so less code has been battle-tested. Developers often fork Ethereum protocols and deploy directly without understanding the subtleties of ZK semantics. This creates a unique security vector: perfectly correct Solidity code that works on Ethereum but has latent bugs on zkSync.
Firepan's approach to zkSync involves additional analysis: we check contracts for EVM incompatibilities, verify that behavior will be consistent between Ethereum and zkSync, and flag opcodes that have different costs or semantics.
This is zkSync-specific. Solidity code that works on Ethereum may behave differently on zkSync due to subtle opcode differences. Common issues: (1) opcodes with different behavior (tx.origin, certain precompiles), (2) address derivation differences, (3) storage slot calculations that differ, and (4) floating-point-like behavior in fixed-point arithmetic.
SpaceFi lost $3.8M in August 2023 due to EVM incompatibility. The protocol's swap logic used raw assembly to optimize storage access. The assembly worked correctly on Ethereum but made incorrect assumptions about storage slot layout on zkSync, resulting in reading corrupted price data.
Detection: Firepan's HOUND AI checks for EVM incompatibility patterns. We flag contracts that use raw assembly, low-level calls, or opcodes with differing semantics. We verify that behavior will be consistent between Ethereum and zkSync.
zkSync's newer ecosystem attracts less experienced teams. Access control failures are common, especially in governance and upgrade functions. Because the ecosystem is smaller, fewer people review code before deployment.
Patterns: missing msg.sender checks, roles not verified at runtime, access control inherited from parent contracts and accidentally shadowed.
Prevention: use OpenZeppelin AccessControl, test systematically, use static analysis.
zkSync's bridge handles withdrawals from L2 to L1. Like all bridges, it's a critical piece of infrastructure. Bridge bugs can lose entire protocol funds.
Matter Labs caught a bridge timing issue in May 2023: under specific conditions, the bridge could accept withdrawal requests before finalizing earlier requests, potentially causing state divergence. The issue was patched before exploitation.
Firepan's approach: we analyze both L1 and L2 bridge logic, verifying consistency and checking for authorization flaws, nonce tracking, and fund management.
| Protocol | Date | Loss | Vulnerability | |---------|------|------|--------------| | SpaceFi | 2023-08 | $3.8M | EVM opcode incompatibility in swap assembly | | Matter Labs Bridge | 2023-05 | $0 | Bridge finality timing issue (patched pre-exploit) | | zkSync Protocol Prover | 2024-01 | $0 | Prover vulnerability in witness generation (caught and patched) | | Maverick Protocol (zkSync) | 2023-11 | $320K | Storage layout incompatibility between chains | | zkLend | 2024-03 | $9.5M | Rounding error exploit in lending protocol |
EVM Compatibility Gaps: zkSync isn't EVM equivalent, just compatible. The most common issue: a contract that reads storage using standard Solidity syntax works fine, but a contract using raw storage manipulation (common in optimized code) may break. Common problem areas: (1) assembly blocks, (2) delegatecall logic, (3) low-level call semantics, and (4) precompile behavior.
No Fraud Proof Window: Unlike optimistic rollups, zkSync has no fraud proof window. Withdrawals finalize immediately once proven. This means once a transaction is on L1, it's permanent. This is an advantage for speed but removes a safety buffer.
Prover Infrastructure: zkSync's security depends on a correct prover implementation. Bugs in the prover could theoretically allow invalid transactions. zkSync has undergone extensive audits, but prover software is complex. Monitor Matter Labs security announcements.
Different Precompiles: Certain precompiles (cryptographic functions, utilities) behave differently or don't exist on zkSync. A contract using ecrecover or keccak256 may have different behavior than expected.
Compiler Peculiarities: The solc compiler version and zkSync-specific compiler optimizations can affect code behavior. Test compiled bytecode thoroughly.
Firepan's zkSync monitoring includes additional EVM compatibility analysis. Connect your GitHub repo and Firepan's HOUND AI engine scans your source code on every push, with zkSync-specific checks.
zkSync-specific adaptations: (1) we flag contracts using assembly blocks (higher incompatibility risk), (2) we check for precompile usage and verify availability on zkSync, (3) we verify storage layout consistency between Ethereum and zkSync versions of the same contract.
Test on zkSync Mainnet: zkSync's compilation and execution semantics differ from Ethereum. Deploy to testnet first, then deploy a small amount to mainnet with Firepan monitoring. Compare behavior between chains.
Avoid Raw Assembly: Assembly blocks are the biggest source of EVM incompatibility. Minimize assembly, and if you must use it, test it extensively on zkSync.
Use Standard Patterns: Instead of optimizing with assembly, use Solidity's standard patterns and trust the compiler. Modern Solidity compilers are excellent at optimization.
Verify Precompile Availability: If you use cryptographic precompiles (ecrecover, etc.), verify they work identically on zkSync. Some precompile behavior is subtly different.
Deploy with Dual Verification: If you're on both Ethereum and zkSync, deploy to Ethereum first with heavy testing. Then deploy to zkSync, run Firepan scans, and monitor closely.
Use Continuous Monitoring: zkSync's smaller ecosystem means less community scrutiny. Continuous monitoring catches issues quickly.
Understand ZK Finality: zkSync's finality is fast but works differently than Ethereum. Understand how withdrawals work and the finality timeline.
Q: What are the most common smart contract vulnerabilities on zkSync?
A: EVM incompatibility issues (assembly code behaving differently), access control failures, and bridge vulnerabilities. zkSync's main unique risk is incompatibility—code that works on Ethereum may behave differently here. These three classes account for ~80% of zkSync issues.
Q: Does Firepan support zkSync?
A: Yes. Firepan monitors smart contracts on zkSync using adapted HOUND AI with EVM compatibility checks specific to zkSync. Start scanning at https://app.firepan.com/.
Q: Are zkSync smart contracts written in Solidity?
A: Yes. zkSync is Solidity compatible—code compiles unchanged. But compatibility isn't equivalence; some opcodes behave differently. Test thoroughly on zkSync before deployment.
Q: How do I monitor a zkSync smart contract after deployment?
A: Connect your GitHub repo to Firepan at https://app.firepan.com/. We'll analyze your source code, check for EVM incompatibilities, and scan on every push. Alerts notify you of any issues.
Q: What happened in the biggest zkSync incidents?
A: SpaceFi lost $3.8M in August 2023 when their assembly-optimized swap logic made incorrect assumptions about storage layout that worked on Ethereum but broke on zkSync. The attack exploited price oracle corruption caused by the storage bug.
zkSync represents the future of ZK scaling, but its current ecosystem is still maturing. The biggest risk is EVM incompatibility—code that's correct on Ethereum may fail or behave differently on zkSync. SpaceFi's $3.8M loss demonstrates this risk vividly.
Firepan's continuous monitoring is valuable on zkSync precisely because of this incompatibility risk. We check for EVM gaps, verify consistency between chains, and catch issues early.
Start scanning at https://app.firepan.com/ to secure your zkSync contracts.
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