matrix-android-sdk2 up to 1.5.0 Message key exchange without entity authentication

Summaryinfo

A vulnerability labeled as critical has been found in matrix-android-sdk2 up to 1.5.0. The impacted element is an unknown function of the component Message Handler. Such manipulation leads to key exchange without entity authentication. This vulnerability is traded as CVE-2022-39248. The attack may be launched remotely. Furthermore, there is an exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in matrix-android-sdk2 up to 1.5.0. It has been rated as critical. Affected by this issue is an unknown part of the component Message Handler. The manipulation with an unknown input leads to a key exchange without entity authentication vulnerability. Using CWE to declare the problem leads to CWE-322. The product performs a key exchange with an actor without verifying the identity of that actor. Impacted is integrity. CVE summarizes:

matrix-android-sdk2 is the Matrix SDK for Android. Prior to version 1.5.1, an attacker cooperating with a malicious homeserver can construct messages that legitimately appear to have come from another person, without any indication such as a grey shield. Additionally, a sophisticated attacker cooperating with a malicious homeserver could employ this vulnerability to perform a targeted attack in order to send fake to-device messages appearing to originate from another user. This can allow, for example, to inject the key backup secret during a self-verification, to make a targeted device start using a malicious key backup spoofed by the homeserver. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-android-sdk2 version 1.5.1 has been modified to only accept Olm-encrypted to-device messages and to stop signing backups on a successful decryption. Out of caution, several other checks have been audited or added. This attack requires coordination between a malicious home server and an attacker, so those who trust their home servers do not need a workaround.

The weakness was shared 09/29/2022 as GHSA-fpgf-pjjv-2qgm. The advisory is shared for download at github.com. This vulnerability is handled as CVE-2022-39248 since 09/02/2022. Technical details are unknown but an exploit is available.

It is declared as proof-of-concept.

Upgrading to version 1.5.1 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 77df720a238d17308deab83ecaa37f7a4740a17e is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• matrix-android-sdk2

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5.0

License

• open-source

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CPE 2.2info

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