CVE-2013-7449 in HexChat
Summary
by MITRE
The ssl_do_connect function in common/server.c in HexChat before 2.10.2, XChat, and XChat-GNOME does not verify that the server hostname matches a domain name in the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.
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Analysis
by VulDB Data Team • 03/04/2025
The vulnerability described in CVE-2013-7449 represents a critical SSL/TLS certificate validation flaw affecting multiple instant messaging clients including HexChat, XChat, and XChat-GNOME versions prior to 2.10.2. This issue stems from the ssl_do_connect function in the common/server.c file which fails to properly implement hostname verification during SSL/TLS handshakes. The flaw allows attackers to perform man-in-the-middle attacks by presenting arbitrary valid certificates that can deceive clients into establishing secure connections with malicious servers. This vulnerability directly impacts the fundamental security principle of certificate-based authentication and undermines the trust model that SSL/TLS protocols are designed to establish. The absence of hostname validation creates a pathway for attackers to intercept communications without detection, potentially compromising user data and credentials transmitted through these applications.
The technical implementation of this vulnerability lies in the improper handling of X.509 certificate validation within the SSL connection establishment process. When a client attempts to connect to an SSL-enabled server, the standard protocol requires verification that the certificate presented by the server matches the hostname being connected to. This process, known as hostname verification or certificate hostname matching, ensures that the certificate is issued for the specific domain or service the client is attempting to reach. The flaw in HexChat and related applications means that the ssl_do_connect function skips this crucial validation step, allowing any valid certificate to be accepted regardless of whether it matches the target hostname. This bypass of certificate validation creates a trust relationship that can be exploited by attackers who possess valid certificates for different domains.
The operational impact of this vulnerability extends beyond simple communication interception, as it fundamentally weakens the security posture of users relying on these instant messaging applications. Attackers can exploit this weakness to perform session hijacking, eavesdrop on private conversations, and potentially gain access to sensitive information transmitted through the affected clients. The vulnerability is particularly dangerous in environments where users communicate sensitive information or conduct business transactions through these applications. From an attacker's perspective, the low complexity and high impact nature of this flaw makes it an attractive target for exploitation, as it requires minimal technical expertise to implement successful attacks. The vulnerability affects not just individual users but also organizations that depend on these applications for secure communications, potentially leading to data breaches and compromised security infrastructure.
Organizations and users should immediately update to HexChat version 2.10.2 or later to remediate this vulnerability, as no effective workarounds exist for the underlying SSL validation flaw. The fix implemented in version 2.10.2 addresses the missing hostname verification by properly implementing certificate validation checks that ensure server certificates match the expected hostnames. System administrators should conduct thorough vulnerability assessments to identify all affected installations and ensure that updates are deployed across all environments where these applications are utilized. Security monitoring should be enhanced to detect potential exploitation attempts, and users should be educated about the importance of keeping their applications updated to prevent exploitation of known vulnerabilities. This vulnerability aligns with CWE-295, which specifically addresses improper certificate validation, and represents a clear violation of the principle of least privilege and secure communication practices as outlined in various security frameworks. The attack pattern described in the ATT&CK framework would classify this under credential access and defense evasion techniques, as it enables attackers to establish persistent access to user communications while avoiding detection mechanisms that would normally flag certificate mismatches.