Incident Overview
The project team discovered that an attacker was able to exploit a flaw in the Bisq trade protocol, targeting individual trades in order to steal trading capital. approximately 3 BTC and 4,000 XMR were stolen from 7 different victims.
The value of the crypto stolen was roughly $22,000 worth of bitcoin (BTC) and $230,000 worth of monero (XMR). In total, that comes to more than $250,000.
To carry out the thefts, the attacker was able to set other users' default fallback address – the destination to which crypto is sent to if a trade fails – to their own. Posing as a seller, they would start a trade with a buyer and simply wait for the time limit to run out. Rather than going to the legitimate owner, the digital assets arrived with the attacker, along with the buyer's payment and security deposit too.
Incident Report
Protocol Information
What the Attacker Needed to Succeed
Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.
What Auditors Should Check
If you're auditing a protocol with similar architecture to Bisq, these are the critical security checks that could have prevented this incident (April 2020).
- Verify all logic paths related to Other are guarded by proper access controls and input validation
- Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs
Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.
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