[01/07, 12:13 am] Training or Consulting or Development On Multi stack Technologies by Ady: https://chatgpt.com/share/6862da98-dd8c-8010-b6e3-3eb81d35161c
[01/07, 1:03 am] Training or Consulting or Development On Multi stack Technologies by Ady: https://pastebin.com/H38mB5QW
Solidity Memory Corruption Exploits via BytesToTypes
, mSlice
, and handleSynPackage
Overview
This document provides a detailed breakdown of a class of origin-level memory corruption attacks in Solidity smart contracts. These attacks abuse unsafe memory manipulation via inline assembly, BytesToTypes
, and mSlice
-style functions, often in relayer functions such as handleSynPackage
. The attack vectors result in fund redirection, logic compromise, or cross-chain exploitation — and can extend into kernel/OS compromise via malicious validator nodes.
Attack Architecture
Diagram: Attack Flow Overview
Vulnerable Function: handleSynPackage
Vulnerability:
- No bounds checking on
msgBytes
- Attacker can craft calldata that tricks inline assembly into reading out-of-bounds memory or misaligned memory
Exploit Modules
1. BytesToTypes.bytesToAddress
Risk:
- Directly reads from memory using unchecked offsets
-
Can be used to:
- Read beyond input boundaries
- Corrupt storage pointers
- Return attacker-controlled address
2. mSlice(bytes, offset, length)
Risk:
- Performs raw memory copy without bounds validation
-
Can:
- Overread and overwrite memory
- Collide with other variables on the heap
Example Exploit Payload
Attacker's Crafted msgBytes
-
When
bytesToAddress(32, msgBytes)
is called:- It reads from the address at offset
0x20
(32 bytes in) - The attacker can place arbitrary 32 bytes there, which is
mload
-ed and truncated to 20 bytes
- It reads from the address at offset
Mind Map: Memory Corruption Exploit Vectors
Exploit Implications
Risk Domain | Consequence |
---|---|
EVM/Memory | Memory corruption, logic misdirection |
Token Logic | Fund redirection to attacker-controlled addresses |
Cross-chain | Sync poisoned state across chains |
Validators | 51% consensus attacks, transaction censorship |
User Wallet | Drained via payload embedded in relay path |
Defensive Strategy
🔒 Hardened Decoding
- Replace unsafe
assembly
decoding withabi.decode
- Validate
msgBytes.length
before any slicing or offset reads - Add explicit length checks:
🛡️ Validate Inputs
- Verify the structure and alignment of relayer data
- Use
safeSlice()
with bounds checking before passing to decoder
🔍 On-Chain Monitoring
- Detect malformed
msgBytes
patterns - Flag suspicious validator nodes that relay corrupted packages
Next Steps
- Simulate attack payload on a local testnet using Foundry or Hardhat
- Patch vulnerable contracts with secure decoding logic
- Integrate validator-level payload verification
- Harden node infrastructure with syscall auditing (Linux) and SIM-based signature verification