apegurus/wormhole-bridge

<!-- Source: rekt.news (CC0) --> <!-- Source: SunWeb3Sec/DeFiHackLabs (Reference) -->

Wormhole Bridge (2022)

Overview

In February 2022, the Wormhole bridge was exploited for 120,000 wETH (worth ~$320M) on the Solana side. The attacker was able to bypass the signature verification process and mint wETH without providing any collateral on the Ethereum side.

Root Cause

The vulnerability existed in the Wormhole's Solana program. Specifically, the verify_signatures function used a deprecated Solana system function load_instruction_at to verify the instructions sysvar. The attacker provided a spoofed sysvar account that mimicked the real sysvar but contained fake data, allowing them to bypass the signature check.

Attack Flow

1. Attacker identified that the verify_signatures function did not properly validate the instructions sysvar account.
2. Attacker created a malicious account that mimicked the instructions sysvar.
3. Attacker called post_vaa with the spoofed sysvar, which made the program believe the signatures were valid.
4. Attacker then called complete_wrapped_eth to mint 120,000 wETH on Solana.
5. Attacker bridged some of the wETH back to Ethereum and swapped the rest on Solana.

Impact

• Loss: ~$320M
• Protocol: Wormhole Bridge
• Chain: Solana / Ethereum
• Date: 2022-02-02

Key Transactions

• Solana Attack tx: 2thJ77y986Yfs4S6996Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9 (Example representation)
• Mint tx: 399986Yfs4S6996Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9Yv9

Detection Heuristics

• Pattern 1: Use of load_instruction_at or other deprecated sysvar loading methods in Solana without proper account validation.
• Pattern 2: Missing checks to ensure that system accounts (like sysvar::instructions) are actually the official system accounts.

Remediation

• Fix 1: Use the modern get_instruction_relative or properly validate the sysvar account address.
• Fix 2: Ensure all system accounts passed to the program are checked against their known addresses.

References

• rekt.news/wormhole-rekt/
• jumpcrypto.com/wormhole-exploit-post-mortem/