CVE-2014-2576 in Claws-mail
Summary
by MITRE
plugins/rssyl/feed.c in Claws Mail before 3.10.0 disables the CURLOPT_SSL_VERIFYHOST check for CN or SAN host name fields, which makes it easier for remote attackers to spoof servers and conduct man-in-the-middle (MITM) attacks.
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Analysis
by VulDB Data Team • 12/18/2024
The vulnerability identified as CVE-2014-2576 resides within the Claws Mail email client software, specifically in the rssyl plugin's feed.c component. This issue affects versions prior to 3.10.0 and represents a critical security flaw that undermines the integrity of secure communications. The vulnerability manifests through the deliberate disabling of SSL certificate verification mechanisms, specifically targeting the CURLOPT_SSL_VERIFYHOST parameter that governs hostname validation during SSL/TLS connections. This configuration error fundamentally weakens the security posture of the email client when processing RSS feeds from remote servers.
The technical flaw stems from the rssyl plugin's implementation where it explicitly disables hostname verification checks that should validate whether the SSL certificate presented by a server matches the hostname being connected to. In standard SSL/TLS implementations, CURLOPT_SSL_VERIFYHOST is designed to ensure that certificates are only accepted when they contain valid hostnames in either the Common Name (CN) field or Subject Alternative Name (SAN) fields of the certificate. When this verification is disabled, an attacker can potentially present a valid certificate for a different hostname, allowing them to impersonate legitimate servers. This behavior directly violates the fundamental principles of certificate-based authentication and creates a pathway for malicious actors to intercept communications without detection.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass full man-in-the-middle attack capabilities. Remote attackers can exploit this weakness to establish fraudulent connections with the email client, potentially intercepting and modifying RSS feed data, injecting malicious content, or redirecting users to compromised servers. The vulnerability is particularly dangerous because it operates at the network layer where users expect secure communication channels. An attacker positioned between the user and the RSS feed server can seamlessly replace legitimate content with malicious payloads, making the attack difficult to detect. This weakness also compromises the trust model that users expect from secure email applications, potentially leading to credential theft, information disclosure, or further compromise through malicious feed content.
From a cybersecurity perspective, this vulnerability maps directly to CWE-295, which addresses "Improper Certificate Validation," and aligns with several ATT&CK techniques including T1041, T1566, and T1190. The flaw represents a failure in secure communication implementation that violates industry standards for SSL/TLS security practices. Organizations using Claws Mail versions prior to 3.10.0 face significant risk exposure, particularly in environments where RSS feed consumption is common and sensitive information might be transmitted through these channels. The vulnerability demonstrates poor security hygiene in SSL implementation and highlights the importance of maintaining up-to-date security libraries and configurations. Security professionals should note that this issue represents a classic example of how seemingly minor configuration changes can create substantial security risks in network applications.
The recommended mitigation strategy involves upgrading to Claws Mail version 3.10.0 or later, where the rssyl plugin properly implements SSL certificate verification. System administrators should also consider implementing additional monitoring for suspicious network activity related to RSS feed connections and ensure that all email client software remains current with security patches. Organizations should review their security policies to ensure that automated feed processing does not inadvertently introduce security vulnerabilities, and consider implementing network-level controls such as certificate pinning or additional content filtering to provide defense-in-depth against potential exploitation of this vulnerability.