CVE-2011-1428 in WeeChat
Summary
by MITRE
Wee Enhanced Environment for Chat (aka WeeChat) 0.3.4 and earlier does not properly verify that the server hostname matches the domain name of the subject of an X.509 certificate, which allows man-in-the-middle attackers to spoof an SSL chat server via an arbitrary certificate, related to incorrect use of the GnuTLS API.
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Analysis
by VulDB Data Team • 10/19/2021
The vulnerability identified as CVE-2011-1428 affects WeeChat version 0.3.4 and earlier, representing a critical flaw in the secure communication implementation of this popular chat client. This issue stems from improper SSL/TLS certificate validation mechanisms that fail to properly verify server hostnames against X.509 certificate subject domains. The flaw allows attackers to execute successful man-in-the-middle attacks by presenting arbitrary SSL certificates that appear legitimate to the client, undermining the fundamental security assurances provided by SSL/TLS encryption protocols.
The technical root cause of this vulnerability lies in the incorrect usage of the GnuTLS API within WeeChat's implementation. Specifically, the application fails to properly validate the Subject Alternative Name (SAN) extension or the Common Name (CN) field in X.509 certificates against the expected server hostname. This improper certificate validation occurs during the SSL handshake process where the client should verify that the certificate presented by the server corresponds to the domain name it is attempting to connect to. According to CWE-295, this represents a failure in proper certificate validation, specifically a weakness in certificate path validation that allows for certificate spoofing attacks.
The operational impact of this vulnerability is severe and far-reaching for users of WeeChat who rely on SSL-encrypted chat connections. Attackers can intercept and modify communications between users and chat servers, potentially gaining access to private messages, credentials, or other sensitive information transmitted through the encrypted channels. The vulnerability enables attackers to create fake SSL chat servers that appear legitimate to unsuspecting users, making it particularly dangerous in environments where secure communication is paramount. This flaw directly violates the principles of secure communication outlined in the TLS protocol specifications and compromises the confidentiality and integrity of chat communications.
This vulnerability aligns with several ATT&CK techniques including T1041 for Exfiltration Over C2 Channel and T1566 for Phishing, as it enables attackers to establish unauthorized communication channels and potentially harvest user credentials. The improper use of SSL/TLS APIs also relates to ATT&CK technique T1552 for Unsecured Credentials, as compromised connections may lead to credential exposure. Organizations and individuals using vulnerable versions of WeeChat should immediately upgrade to versions 0.3.5 or later where this certificate validation issue has been addressed through proper implementation of GnuTLS API functions that correctly validate server hostnames against certificate subject domains.
The fix implemented in subsequent versions addresses the core issue by ensuring that certificate validation properly checks the hostname against the certificate's subject alternative name or common name fields. This correction ensures that WeeChat performs proper SSL/TLS certificate verification as mandated by industry standards and security best practices. The resolution demonstrates the critical importance of proper cryptographic API usage in client applications and highlights the potential consequences of inadequate security implementation in open-source software projects that handle sensitive communications.