The $8m Platypus flash mortgage assault was made attainable due to code that was in the flawed order, in line with a publish mortem report from Platypus auditor Omniscia. The auditing firm claims the problematic code didn’t exist within the model they noticed.
— Omniscia (@Omniscia_sec) February 17, 2023
In response to the report, the Platypus MasterPlatypusV4 contract “contained a deadly false impression in its emergencyWithdraw mechanism” which made it carry out “its solvency examine earlier than updating the LP tokens related to the stake place.”
The report emphasised that the code for the emergencyWithdraw operate had all the obligatory components to stop an assault, however these components have been merely written within the flawed order, as Omniscia defined:
“The problem might have been prevented by re-ordering the MasterPlatypusV4::emergencyWithdraw statements and performing the solvency examine after the person’s quantity entry has been set to 0 which might have prohibited the assault from going down.”
Omnisia admitted that they audited a model of the MasterPlatypusV4 contract from Nov. 21 to Dec. 5, 2021. Nevertheless, this model “contained no integration factors with an exterior platypusTreasure system” and due to this fact didn’t comprise the misordered strains of code. From Omniscia’s standpoint, this suggests that the builders should have deployed a brand new model of the contract sooner or later after the audit was made.
The auditor claims that the contract implementation at Avalanche (AVAX) C-Chain tackle 0xc007f27b757a782c833c568f5851ae1dfe0e6ec7 is the one which was exploited. Strains 582-584 of this contract seem to name a operate referred to as “isSolvent” on the PlatypusTreasure contract, and contours 599-601 seem to set the person’s quantity, issue, and rewardDebt to zero. Nevertheless, these quantities are set to zero after the “isSolvent” operate has already been referred to as.
The Platypus crew confirmed on Feb. 16 that the attacker exploited a “flaw in [the] USP solvency examine mechanism,” however the crew didn’t initially present additional element. This new report from the auditor sheds additional gentle on how the attacker could have been capable of accomplish the exploit.
The Platypus crew introduced on Feb. 16 that the attack had occurred. It has tried to contact the hacker and get the funds returned in change for a bug bounty. The attacker used flashed loans to carry out the exploit, which has similarities to the technique used within the Defrost Finance exploit of Dec. 25.