Incident Overview
The owner of the bitcoin betting site Just-Dice, a rival to SatoshiDice, had a severe moment of panic when a user taking advantage of a human error caused him to lose 1,300 bitcoins (around $116,090 at the time of writing).
Known only as ‘dooglus’, the owner revealed on the Bitcoin Talk forum that he had made something of a colossal mistake.
was this: a player won a load of bitcoins on the site and asked to withdraw them, dooglus paid out, but forgot to remove the balance from the user’s Just-Dice account. The user then gambled — and lost — the bitcoins that were left in his account and dooglus covered the loss out of his own pocket.
When he realized his mistake, dooglus contacted the user, who claimed he had left his laptop in a café and that someone else logged onto his Just-Dice account and gambled the money.
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 Just-Dice, these are the critical security checks that could have prevented this incident (July 2013).
- Verify all logic paths related to Access Control are guarded by proper access controls and input validation - see the Access Control Attacks attack class for patterns
- 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.
Free TrialRelated Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Sources & References
Learn to Prevent the Next Just-Dice
The Just-Dice hack is one of many attacks that skilled auditors are trained to detect before deployment. Master real exploit patterns and defense techniques with hands-on Web3 security training.