Ankr Bridge Drained of $303K in Multi-Token Exploit

Ankr’s Ethereum cross-chain bridge has suffered an exploit involving five unauthorized withdrawals that drained more than $303,000 in crypto assets on Nov. 9, according to CryptoNews. Blockchain security firm Blockaid identified the attack, reporting that an attacker used a small deposit on Optimism to withdraw assets locked in Ankr’s Ethereum bridge.

The attack took place between 3:09 a.m. and 3:12 a.m. Eastern Time, sending different tokens to the same destination wallet. Transaction records showed the largest component of the loss was approximately 82.91 ankrETH worth $216,370, alongside 515,206 ankrPOL tokens valued at $56,372, and approximately 7.98 million ANKR tokens accounting for $30,857. Two other assets, aMATICb and aETHb, were also transferred during the attack.

Reused Deposit Vector

The reported exploit centered on a deposit originally made through Optimism on Nov. 3. The transaction analysis showed the deposit involved 0.0044024803 ankrETH and had already been redeemed on Ethereum that same day. However, the attacker referenced the same deposit when submitting five new withdrawal requests on Nov. 9, containing modified receipt information identifying a different recipient, larger withdrawal amounts, and different tokens.

Response and Status

Blockaid flagged the exploit as ongoing while moving the bridge's assets into a new wallet. At 3:49 a.m. Eastern Time, the bridge’s transaction history showed no further activity, though its public pause flag remained false. Ankr had not responded to questions regarding affected services, bridge security, or possible user reimbursements at the time of reporting.

Key facts

• Ankr's Ethereum bridge lost over $303,000 across five unauthorized withdrawals on Nov. 9.
• The attacker reused a previously redeemed Optimism deposit from Nov. 3 to execute the exploit.
• Stolen assets included ankrETH, ankrPOL, ANKR tokens, aMATICb, and aETHb.
• Blockaid flagged the incident as an ongoing exploit.