Incident Overview
Paribus was exploited due to a reentrancy issue, resulting in the loss of 69,696 $USD worth of $ETH.
Paribus is a cross-chain lending and borrowing protocol. The protocol suffered an exploit on the Arbitrum layer-two chain. The root cause was a well-known reentrancy vulnerability from an old version of CompoundV2 that Paribus had forked. The attacker deployed two malicious unverified contracts and used this vulnerability to withdraw funds multiple times before updating their balance on-chain. As a result, they were able to drain 35.2 $ETH which is currently worth 69,696 $USD at the time of writing.
All stolen assets were transferred through Stargate Bridge in two transactions.
Attacker address:
https://arbiscan.io/address/0x014abff0…9e5504
Malicious transaction:
https://arbiscan.io/tx/0x0e29dcf4…2390af
Malicious contracts:
https://arbiscan.io/address/0xcd31e27f…f8c50b
https://arbiscan.io/address/0xec05281d…29dfe7
Incident Report
Protocol Information
Market Context at Time of Hack
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 Paribus, these are the critical security checks that could have prevented this incident (April 2023).
- Verify all logic paths related to Reentrancy are guarded by proper access controls and input validation - see the Reentrancy attack class for patterns
- Check that all state-changing functions follow the Checks-Effects-Interactions (CEI) pattern to prevent reentrancy and logic ordering bugs
- 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 Paribus
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