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Exposure of private backup key to Element's rageshake servers

High
dkasak published GHSA-j9f4-49p7-x4cq May 15, 2024

Package

Element X iOS (io.element.elementx) (iOS)

Affected versions

>=1.5.2,<1.6.7

Patched versions

1.6.7

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 iOS device (>=1.5.2,<1.6.7), this key will uploaded to Element's rageshake server.

Patches

The issue has been patched in Element X iOS 1.6.7.

Workarounds

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

References

Severity

High

CVE ID

No known CVE

Weaknesses

No CWEs