CVE-2010-4533 in Offlineimap
Summary
by MITRE
offlineimap before 6.3.4 added support for SSL server certificate validation but it is still possible to use SSL v2 protocol, which is a flawed protocol with multiple security deficiencies.
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Analysis
by VulDB Data Team • 02/13/2024
The vulnerability identified as CVE-2010-4533 affects offlineimap versions prior to 6.3.4 and represents a significant security weakness in the email synchronization tool's cryptographic implementation. This issue stems from the software's handling of SSL/TLS protocols, specifically its continued support for SSL version 2 which was deprecated decades ago due to fundamental security flaws. The vulnerability exists despite offlineimap's introduction of SSL server certificate validation capabilities in version 6.3.4, indicating that while the software addressed certificate validation concerns, it failed to properly deprecate the insecure SSL v2 protocol that remains susceptible to various cryptographic attacks including man-in-the-middle attacks and session hijacking attempts.
The technical flaw manifests in the protocol negotiation mechanism where offlineimap continues to accept connections using SSL v2 despite the protocol's known vulnerabilities and industry-wide deprecation. SSL v2 suffers from multiple critical weaknesses including weak cryptographic algorithms, lack of proper authentication mechanisms, and susceptibility to downgrade attacks that allow attackers to force connections to use the insecure protocol. This creates a dangerous situation where even though the software implements certificate validation, the underlying protocol remains exploitable through SSL v2's inherent design flaws. The vulnerability falls under CWE-327, which specifically addresses the use of weak cryptographic algorithms, and represents a failure to properly implement secure protocol handling as outlined in the NIST SP 800-52 guidelines for secure protocol selection.
The operational impact of this vulnerability is substantial as it provides attackers with multiple attack vectors to compromise email synchronization processes. An attacker positioned between the client and server can exploit the SSL v2 support to perform man-in-the-middle attacks, potentially intercepting email communications or modifying synchronization data. This weakness particularly affects users who rely on offlineimap for secure email access, as the vulnerability undermines the security assurances that should be provided by the SSL/TLS encryption layer. The risk is exacerbated when users connect to email servers that may be configured to accept SSL v2 connections or when network traffic is not properly secured at the network level. According to ATT&CK framework technique T1566, this vulnerability enables initial access through credential compromise or network infiltration, while T1071 demonstrates how insecure protocols can be leveraged for data exfiltration and command and control communications.
The recommended mitigation strategy involves immediate upgrade to offlineimap version 6.3.4 or later, which properly disables SSL v2 protocol support and enforces secure protocol negotiation. System administrators should also implement network-level controls to prevent SSL v2 connections at the firewall or proxy level, ensuring that even if the application fails to properly disable the protocol, network infrastructure blocks insecure connections. Additionally, users should verify their email server configurations to ensure that SSL v2 is disabled at the server level, and implement proper certificate pinning mechanisms where possible. The vulnerability highlights the importance of proper protocol handling and adherence to security standards such as those defined in RFC 6176 which specifically recommends against using SSL v2 in modern implementations. Organizations should also conduct regular security assessments to identify and remediate similar protocol-level vulnerabilities in their email infrastructure and other network services that may be susceptible to similar downgrade attacks through legacy protocol support.