GHSA-fpgf-pjjv-2qgm

Suggest an improvement
Source
https://github.com/advisories/GHSA-fpgf-pjjv-2qgm
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2022/09/GHSA-fpgf-pjjv-2qgm/GHSA-fpgf-pjjv-2qgm.json
JSON Data
https://api.test.osv.dev/v1/vulns/GHSA-fpgf-pjjv-2qgm
Aliases
Published
2022-09-30T04:37:39Z
Modified
2023-11-01T04:59:47.408026Z
Severity
  • 8.6 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N CVSS Calculator
Summary
matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion
Details

Impact

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.

Patches

matrix-android-sdk2 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: - Cleartext m.room_key, m.forwarded_room_key and m.secret.send todevice messages are discarded. - Secrets received from untrusted devices are discarded. - Key backups are only usable if they have a valid signature from a trusted device (no more local trust, or trust-on-decrypt). - The origin of a to-device message should only be determined by observing the Olm session which managed to decrypt the message, and not by using claimed senderkey, user_id, or any other fields controllable by the homeserver.

Workarounds

As this attack requires coordination between a malicious home server and an attacker, if you trust your home server no particular workaround is needed. Notice that the backup spoofing attack is a particularly sophisticated targeted attack.

We are not aware of this attack being used in the wild, though specifying a false positive-free way of noticing malicious key backups key is challenging.

As an abundance of caution, to avoid malicious backup attacks, you should not verify your new logins using emoji/QR verifications methods until patched. Prefer using verify with passphrase.

References

Blog post: https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients

For more information

If you have any questions or comments about this advisory, e-mail us at security@matrix.org.

Database specific
{
    "nvd_published_at": "2022-09-28T20:15:00Z",
    "github_reviewed_at": "2022-09-30T04:37:39Z",
    "severity": "HIGH",
    "github_reviewed": true,
    "cwe_ids": [
        "CWE-287",
        "CWE-322"
    ]
}
References

Affected packages

Maven / org.matrix.android:matrix-android-sdk2

Package

Name
org.matrix.android:matrix-android-sdk2
View open source insights on deps.dev
Purl
pkg:maven/org.matrix.android/matrix-android-sdk2

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.5.1

Affected versions

0.*

0.0.2

1.*

1.2.1
1.3.0
1.3.2
1.3.4
1.3.7
1.3.8
1.3.9
1.3.10
1.3.13
1.3.14
1.3.18
1.4.2
1.4.4
1.4.11
1.4.13
1.4.14
1.4.16
1.4.25
1.4.27
1.4.32
1.4.34
1.4.36

Database specific

{
    "last_known_affected_version_range": "<= 1.4.36"
}