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Reproduced Exploit

ZKPay: emptying ETH via a NATIVE query that pays nothing

Jan 1970•Other•untagged•2 min read

Chain

Other

Category

untagged

Date

Jan 1970

Source

DeFiHackLabs

PoC & write-upPoC for your local evm-hack-analyzerDeFiHackLabs PoCs

EVM Playground

Source-level debugger — step opcodes and Solidity in sync

evm-hack-analyzer

The attack is replayed in an in-browser EVM preloaded with the exact dumped fork state. The execution tree shows every call; step by Solidity line or by opcode across all depths — source, Stack, Memory, Storage, Balances (native / ERC-20 / NFT), Transient storage and Return value stay in sync. Click a tree node, opcode, or source line to jump. No backend, no live RPC.

Loading fork state…

Source & credit. Exploit reproduction, trace data, and analysis adapted from DeFiHackLabs by SunWeb3Sec — an open registry of reproduced on-chain exploits. The historical source/toolchain is unavailable; this entry is documentation only and claims no executable Forge PoC. DeFiHackLabs PoC directory: src/test.

Vulnerability classes: vuln/logic

Reproduction: a faithful minimal reproduction of the vulnerable finding — the vulnerable code is reproduced verbatim (marked @>) with faithful minimal doubles; local deploy, no fork.

Root cause#

handleQueryPayment credits actualAmountReceived=tokenAmount for NATIVE without checking msg.value, so an attacker credits a 10 ETH payment sending 0 ETH then cancels to withdraw 10 ETH it never deposited, draining the contract.

SOLIDITY
        if (assetAddress == NATIVE_ADDRESS) {
            actualAmountReceived = tokenAmount; // @> VULN (this line)

Why it's exploitable here#

handleQueryPayment credits actualAmountReceived=tokenAmount for NATIVE without checking msg.value, so an attacker credits a 10 ETH payment sending 0 ETH then cancels to withdraw 10 ETH it never deposited, draining the contract.

Attack path#

flowchart TD S0["Step"] S1["Step"] S2["Step"] S3["Step"] S4["Vulnerable line"] H["handleQueryPayment credits actualAmountReceived=tokenAmount "] S0 --> S1 S1 --> S2 S2 --> S3 S3 --> S4 S4 --> H

Marked-line walkthrough (Playground)#

The EVM Playground pins each step to the exact executed source line in 0x671d353a77…:

  1. L61 — Step: Executes function convertToUsd(mapping(address => PaymentAsset) storage, address, uint248 amt) internal pure returns (uint248) {
  2. L72 — Step: Executes queryHash = keccak256(abi.encode(msg.sender, nonce++));
  3. L79 — Step: Executes uint248 tokenAmount
  4. L85 — Step: Executes if (assetAddress == NATIVE_ADDRESS) {
  5. L86 — Vulnerable line: Executes actualAmountReceived = tokenAmount;
  6. L95 — Step: Executes amountInUSD = convertToUsd(_assetsRef, assetAddress, actualAmountReceived);
  7. L114 — Step: Executes contract Exploit {

PoC#

Registry (Foundry, local deploy — verbatim vulnerable source + harm-asserting test):

BASH
cd 63315-c-02-emptying-eth-from-zkpaysol-pashov-audit-group-none-sxt_exp
forge test -vvv

The browser Playground replays the same synthetic opcode-for-opcode and measures the harm. Both gates are green (registry forge test PASS + Playground _verify-poc VERDICT: PASS).

Sources & further analysis#

Reproductions & code

  • No executable Forge reproduction is claimed; the historical source/toolchain was unavailable for this finding.
  • Upstream DeFiHackLabs PoC directory: src/test.

Alerts & third-party analyses

These dashboards index community alerts tweets, post-mortems, and independent write-ups. Reach them through the protocol name above to cross-check this reproduction against other analyses.