Portal 🌉 Bridge

On February 2, 2022, an attacker exploited the Solana side of the Wormhole cross-chain bridge — the product users interacted with under the brand Portal — and minted 120,000 wrapped ETH (whETH) without depositing any real Ether as collateral. The attacker redeemed roughly 93,750 whETH back to native ETH on Ethereum and swapped the rest for SOL and other assets, netting close to $326 million, one of the largest DeFi exploits on record (Chainalysis, Rekt).

How the attack worked

Wormhole's Solana contract mints wrapped tokens only after verifying a Verifiable Action Approval (VAA) — a message signed by the bridge's guardian set, confirming that matching collateral was locked on the source chain. To check that signature, the program was supposed to call Solana's native Secp256k1 verification program and confirm the call genuinely came from Solana's system program. Instead of the current API for that check, the contract relied on a deprecated function, load_instruction_at, which failed to validate the caller's address (Halborn).

The attacker exploited that gap by crafting a fake "Instructions sysvar" account and feeding it into the verification call. Because the deprecated function skipped the address check, the forged account was accepted as if it were the genuine system account, and the guardian signature check passed even though no real signature had ever been produced. With a spoofed VAA in hand, the attacker called the bridge's complete_wrapped function and minted 120,000 whETH out of thin air — no ETH was ever locked on the Ethereum side.

The "Signature Exploit" label fits precisely: the flaw sat in signature-verification plumbing, not in economic logic like price oracles or flash loans. It differs from typical bridge validator-key thefts (Ronin being the best-known case) in that no private keys were stolen — the check meant to require valid signatures was tricked into passing without any.

What happened next

Within hours, Wormhole's team left a $10 million white-hat bounty offer on-chain for the attacker, proposing to let them keep that sum in exchange for returning the rest and explaining the exploit. The attacker never responded. Jump Trading/Jump Crypto, the trading firm behind Wormhole's operator Certus One, replaced the missing collateral by injecting roughly 120,000 ETH (about $326 million at the time) into the bridge within about a day, restoring whETH's 1:1 backing and averting a cascading liquidation risk across Solana DeFi protocols that used whETH as collateral (Chainalysis).

This was a third-party bailout, not a recovery of stolen funds: the attacker was never identified and kept the proceeds. A later update noted the funds had been converted into staked ETH and used as collateral in lending protocols. Wormhole itself kept operating, later raised new funding, patched the contract, and expanded its guardian set.

What this means

• The exploit sat entirely in bridge-side signature verification, a layer invisible to end users — no wallet hygiene or contract-reading by a depositor could have flagged it in advance.
• Wrapped-asset bridges carry a specific tail risk: the wrapped token's peg depends entirely on the bridge contract correctly gating minting, so a single verification bug can decouple its price from the underlying asset instantly.
• Recovery here was possible only because Wormhole had a well-capitalized corporate backer; bridges without a comparable balance sheet behind them have no equivalent safety net when this class of bug surfaces.
• The incident pushed the industry toward auditing deprecated or legacy API usage specifically in cross-chain verification code, and toward more conservative, multi-step signature checks in bridge contracts generally.