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Exposure of private backup key to Element's rageshake servers

High
dkasak published GHSA-42h8-mgpm-8gwv May 15, 2024

Package

Element X Android (io.element.android.x) (Android)

Affected versions

>=0.4.1,<0.4.12

Patched versions

0.4.12

Description

Introduction

In Matrix, the server-side key backup stores encrypted copies of Matrix message keys. This facilitates key sharing between a user's devices and provides a redundant copy in case all devices are lost. The key backup uses asymmetric cryptography, with each server-side key backup assigned a unique public-private key pair.

Rageshakes are a feature in Element clients that allow users to report bugs by shaking their device, which also uploads debug logs for analysis.

Impact

A bug in the matrix-sdk-crypto create (a part of the Matrix Rust SDK project; CVE-2024-34353 / GHSA-9ggc-845v-gcgv) resulted in the private part of the backup key pair being mistakenly logged into debug logs. If in such a case a user submits a bug report (i.e. rageshakes) from an affected Element X Android version (>=0.4.1, <0.4.12), this key will uploaded to Element's rageshake server.

Patches

The issue has been patched in Element X Android 0.4.12.

Workarounds

Don't submit bug reports (rageshakes) from affected Element X Android versions.

References

Severity

High

CVE ID

No known CVE

Weaknesses