Ledger patched an Ethereum app bug that could show one transaction and sign another

Ledger users should update the Ethereum app to version 1.22.2 after official code changes showed that a malicious dApp or other connected host could start a second signing command while a transaction was still under review.

In the path described by security company TestMachine, pressing approve could return a signature for substituted data instead of the transaction shown on the device.

TestMachine said on Aug. 22 that the attack required a dApp with WebHID access. The group said a second command could replace the transaction held in memory without opening a new review, leaving the original details on screen while the device signed the replacement.

It said the behavior was validated on Ledger Flex.

Ledger’s code history shows one official fix commit saying new signing commands could tear down an active review before returning an error. Another added state checks because approval callbacks previously signed without confirming that the app remained in the expected signing state.

Version 1.22.2 closes that documented path by refusing a new signing session during an active review and rejecting an approval callback when the state no longer matches. The reviewed sources establish a code-level fix for those entry and callback defects.

… Continue reading the full article at the original source below.