CVE-2020-24837
📋 TL;DR
This integer underflow vulnerability in ZCFees smart contract allows attackers to manipulate transaction timestamps to block execution of the process function. It affects systems running vulnerable versions of ZCFees smart contracts. The vulnerability enables denial of service by preventing normal contract operations.
💻 Affected Systems
- ZCFees smart contract
📦 What is this software?
Zcfees by Zcfees Project
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service preventing all fee processing operations, potentially freezing funds or disrupting the entire fee management system.
Likely Case
Temporary disruption of fee processing functions, causing delays in financial operations and requiring manual intervention.
If Mitigated
Minimal impact if proper input validation and timestamp controls are implemented at the application layer.
🎯 Exploit Status
Requires ability to manipulate transaction timestamps, which may involve blockchain manipulation techniques
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in CVE
Vendor Advisory: Not provided in CVE
Restart Required: No
Instructions:
1. Deploy patched smart contract version 2. Migrate all data and funds to new contract 3. Update all references to use new contract address
🔧 Temporary Workarounds
Input validation wrapper
allImplement external validation layer to check timestamp validity before transactions reach vulnerable contract
🧯 If You Can't Patch
- Implement monitoring for unusual timestamp patterns in transactions
- Deploy proxy contract with safe math operations to intercept calls to vulnerable contract
🔍 How to Verify
Check if Vulnerable:
Check if deployed contract matches vulnerable code at etherscan.io/address/0x9d79c6e2a0222b9ac7bfabc447209c58fe9e0dcc#codeCheck Version:
Not applicable for smart contracts - verify by contract address and bytecodeVerify Fix Applied:
Verify new contract uses safe math operations and proper bounds checking for timestamp calculations📡 Detection & Monitoring
Log Indicators:
- Failed process function calls
- Unusual timestamp values in transaction logs
Network Indicators:
- Multiple failed transactions to contract address
- Transaction timestamp manipulation patterns
SIEM Query:
Not applicable - blockchain transactions require specialized monitoring