Ledger Wallet Vulnerability; Users Must Update Ethereum App to Version 1.22.2

A security vulnerability has been identified in the Ethereum application of Ledger hardware wallets that could allow a malicious dApp to sign a transaction different from what is displayed on the device screen under certain conditions. Ledger has released version 1.22.2 of the Ethereum application to address this issue, and users are urged to install it as soon as possible.

According to Mihan Blockchain, this vulnerability was related to the way simultaneous signature requests were managed. In the attack scenario, the details of the original transaction were still displayed on the device screen, but a second request could replace it in memory, ultimately sending different data for signing to the device.

How Did the Vulnerability Work?

According to a report by the security company TestMachine, exploiting this bug required a dApp with WebHID access, a feature that allows certain web applications to communicate directly with hardware devices.

In this scenario, the attacker could send a second signature request while the user was reviewing a transaction. This request would replace the previous transaction data in memory without initiating a new review process. As a result, the user would still see the initial transaction information on the display but would sign the replaced data upon selecting the confirm option.

TestMachine also stated that it reproduced this scenario on the Ledger Flex.

What Changes Did Ledger Make to Fix the Issue?

The recorded changes in Ledger's official code indicate that the company added two security controls to prevent the attack. First, the application no longer allows a new signature request to interrupt the review process of an ongoing transaction. Second, when receiving a confirmation command, the current status of the signing process is checked, and if it does not match the expected status, the request will be rejected.

These fixes have been implemented in version 1.22.2 of the Ethereum application, which was released on August 12. However, TestMachine claims that this version has not yet been fully made available to users.

According to TestMachine, due to the use of shared code, this flaw could also affect the Nano X, Nano S Plus, Stax, and Apex models. The official file for version 1.22.2 also lists these models alongside Ledger Flex as target devices for the Ethereum application.

Ledger has not yet specified which was the first vulnerable version of this application. Therefore, it is unclear how many previous versions contained this bug.

Discrepancy Between Ledger and TestMachine on Discovering the Vulnerability

Charles Guillemet, Chief Technology Officer of Ledger, announced on August 23 that Ledger's internal security team, Ledger Donjon, had identified this bug before TestMachine contacted the company through its bug bounty program.

Guillemet stated that this team had identified and fixed the issue in some "transparent signing" processes about two weeks before his statement. In contrast, TestMachine claimed that the Azimuth system identified this vulnerability and shared its findings with Ledger, confirming their validity.

Despite this discrepancy in narratives regarding the timing and manner of discovering the vulnerability, both parties have confirmed the existence of the problem and its fix in the application code.

It is worth noting that, so far, there have been no confirmed cases of exploitation of this vulnerability in the real world, theft of user assets, or extraction of private keys reported. However, since the flaw directly relates to the transaction verification and signing process, updating the application is of particular importance.

Ledger users should check the version of the Ethereum application on their device and upgrade it to 1.22.2 if they are using an older version. Ledger has also advised users to keep not only the Ethereum application but also the device's operating system, other applications, and related client software updated to the latest version.

Additionally, this vulnerability differs from another security flaw previously reported in Ledger's native Zilliqa application and is unrelated to the 2023 attack on Connect Kit.