CVE-2016-10376 in Gajim
Summary
by MITRE
Gajim through 0.16.7 unconditionally implements the "XEP-0146: Remote Controlling Clients" extension. This can be abused by malicious XMPP servers to, for example, extract plaintext from OTR encrypted sessions.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability described in CVE-2016-10376 affects Gajim, an open-source instant messaging client, specifically versions through 0.16.7. This issue stems from the unconditional implementation of XEP-0146 Remote Controlling Clients extension, which represents a significant security flaw in the client's handling of XMPP protocol extensions. The vulnerability operates at the protocol level, exploiting how Gajim processes incoming XMPP messages and commands without proper validation of the originating server's legitimacy. This design decision creates an inherent trust model that malicious actors can leverage to manipulate client behavior.
The technical flaw manifests through the improper handling of XEP-0146 commands, which allows remote XMPP servers to issue control instructions to connected clients. When a malicious server implements this extension, it can intercept and manipulate OTR encrypted sessions by extracting plaintext content that should remain protected. The vulnerability essentially disables the client's ability to distinguish between legitimate and malicious control commands, creating a pathway for man-in-the-middle attacks and session hijacking. This issue directly relates to CWE-284 Access Control and CWE-310 Cryptographic Issues, as it undermines both access controls and encryption integrity.
The operational impact of this vulnerability extends beyond simple message interception, as it fundamentally compromises the security assurances that users expect from encrypted communication. When attackers exploit this vulnerability, they can extract sensitive information from OTR encrypted sessions, potentially exposing private conversations, personal data, and confidential communications. The attack vector requires only that a user connects to a malicious XMPP server that implements the problematic extension, making it particularly dangerous in environments where users may connect to untrusted servers or when server compromise occurs through other means. This vulnerability affects the core security model of Gajim's encryption implementation and can be exploited without user interaction or explicit consent.
Mitigation strategies for this vulnerability require immediate software updates to versions that properly implement XEP-0146 with appropriate access controls and authentication mechanisms. Users should disable or remove support for untrusted XMPP extensions and ensure that their clients only connect to servers they trust. Organizations should implement network-level controls to monitor and restrict XMPP traffic to known good servers. From a defense perspective, this vulnerability aligns with ATT&CK technique T1566 Credential Access through Social Engineering, as it represents a method of compromising user credentials and communications through protocol-level manipulation. The recommended approach includes disabling unsupported XMPP extensions, implementing proper server certificate validation, and maintaining updated client software to prevent exploitation of this remote control vulnerability.