CVE-2004-0885 in HTTP Server
Summary
by MITRE
The mod_ssl module in Apache 2.0.35 through 2.0.52, when using the "SSLCipherSuite" directive in directory or location context, allows remote clients to bypass intended restrictions by using any cipher suite that is allowed by the virtual host configuration.
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability described in CVE-2004-0885 represents a critical security flaw in the Apache web server's mod_ssl module that affects versions between 2.0.35 and 2.0.52. This issue stems from improper handling of SSL cipher suite configurations when the SSLCipherSuite directive is applied within directory or location contexts rather than the main server configuration. The flaw creates a significant bypass mechanism that undermines the intended security policies established by administrators who wish to restrict specific cipher suites for certain directories or locations within their web applications.
The technical implementation of this vulnerability occurs due to how Apache processes SSL configuration directives when they are nested within directory or location blocks. When an administrator defines SSLCipherSuite in a directory context, the mod_ssl module should enforce those specific cipher suite restrictions. However, the flaw allows remote clients to negotiate cipher suites that are permitted at the virtual host level, effectively bypassing the more restrictive directory-level configurations. This behavior violates the principle of least privilege and configuration isolation that security administrators rely upon to maintain granular control over their SSL/TLS implementations.
From an operational perspective, this vulnerability creates substantial risk for organizations that depend on Apache with mod_ssl for their web services. Attackers can exploit this weakness to downgrade SSL connections to less secure cipher suites that may be vulnerable to known attacks such as those targeting weak encryption algorithms or short key lengths. The impact extends beyond simple encryption downgrade attacks as it can enable more sophisticated exploitation techniques including man-in-the-middle attacks where attackers leverage the bypassed restrictions to establish connections using weaker cryptographic parameters. This vulnerability directly violates security standards established by organizations such as NIST and the CWE-264 weakness category, which addresses "Permissions, Privileges, and Access Controls" by allowing unauthorized access to less restricted cryptographic configurations.
The attack surface for this vulnerability is particularly concerning given that many organizations implement directory-specific security policies to protect sensitive resources while maintaining more permissive configurations for general web content. This flaw essentially neutralizes the security controls that administrators put in place to isolate different parts of their web applications. The vulnerability also relates to ATT&CK technique T1566 which involves social engineering and credential access through network protocols, as attackers can leverage the bypassed restrictions to compromise connections that should have been protected by stronger encryption policies. Organizations using Apache with mod_ssl in environments where directory-level SSL configuration is critical for compliance with standards such as PCI DSS or HIPAA face particular risk since this vulnerability can undermine the cryptographic protections that these regulations require.
Mitigation strategies for CVE-2004-0885 primarily involve upgrading to Apache versions that have addressed this specific flaw, which were released after version 2.0.52. Additionally, administrators should implement comprehensive SSL/TLS configuration reviews to ensure that cipher suite restrictions are properly applied at the virtual host level rather than relying on directory-level configurations that may be vulnerable to this bypass. Security teams should also consider implementing network monitoring to detect unusual SSL negotiation patterns that might indicate exploitation attempts. The vulnerability underscores the importance of maintaining current security patches and following secure configuration practices for web servers, particularly those handling sensitive data. Organizations should also consider implementing additional layers of security including SSL/TLS monitoring tools and regular security assessments to identify similar configuration weaknesses that could be exploited in similar ways.