CVE-2013-2155 in XML Security for C++
Summary
by MITRE
Apache Santuario XML Security for C++ (aka xml-security-c) before 1.7.1 does not properly validate length values, which allows remote attackers to cause a denial of service or bypass the CVE-2009-0217 protection mechanism and spoof a signature via crafted length values to the (1) compareBase64StringToRaw, (2) DSIGAlgorithmHandlerDefault, or (3) DSIGAlgorithmHandlerDefault::verify functions.
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Analysis
by VulDB Data Team • 01/04/2022
The vulnerability identified as CVE-2013-2155 affects Apache Santuario XML Security for C++ version 1.7.1 and earlier, representing a critical flaw in the library's handling of length validation within cryptographic signature processing operations. This issue stems from inadequate validation of length parameters during base64 string comparisons and digital signature verification processes, creating potential attack vectors that could lead to both denial of service conditions and security bypass scenarios. The affected functions include compareBase64StringToRaw, DSIGAlgorithmHandlerDefault, and DSIGAlgorithmHandlerDefault::verify, which form core components of the XML signature validation framework. The vulnerability's impact extends beyond simple service disruption as it specifically undermines the protection mechanisms established in CVE-2009-0217, which was designed to prevent signature spoofing attacks through improper length handling.
The technical exploitation of this vulnerability occurs through crafted malicious length values that manipulate how the xml-security-c library processes cryptographic signatures. When the library encounters these malformed length parameters, it fails to properly validate the input data, allowing attackers to either cause buffer overflows or memory corruption that results in denial of service conditions. More critically, the flaw enables attackers to bypass the security protections implemented in CVE-2009-0217, which was specifically designed to prevent attackers from crafting signatures that could appear valid while actually containing malicious content. This bypass capability creates a significant risk for systems relying on xml-security-c for XML signature validation, as it allows adversaries to potentially forge signatures that would otherwise be detected by the security mechanisms. The vulnerability manifests in the comparison functions that handle base64 encoded data, where improper length validation can lead to out-of-bounds memory access patterns and potential code execution scenarios.
From an operational perspective, systems utilizing Apache Santuario XML Security for C++ in environments where XML signatures are processed represent high-risk targets for exploitation. The vulnerability affects any application that relies on xml-security-c for validating XML signatures, including web services, enterprise applications, and security infrastructure components. The denial of service aspect creates immediate operational concerns as attackers can disrupt service availability by triggering memory corruption or resource exhaustion conditions. Additionally, the signature spoofing capability poses long-term security risks as it undermines the integrity guarantees that XML signatures are designed to provide. Organizations deploying applications that depend on xml-security-c for security validation may experience unauthorized access, data tampering, or impersonation attacks if this vulnerability remains unpatched. The attack vectors are particularly concerning in environments where XML signatures are used for authentication, authorization, or data integrity verification within critical business processes or security protocols.
Mitigation strategies for CVE-2013-2155 require immediate deployment of the patched xml-security-c version 1.7.1 or later, which addresses the improper length validation issues in the affected functions. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing the vulnerable library and prioritize patching efforts accordingly. Network segmentation and monitoring should be implemented to detect potential exploitation attempts, particularly around XML signature processing endpoints. Input validation controls should be enhanced at application layers to provide additional defense-in-depth measures, though these are not substitutes for the core library patch. Security teams should also review existing XML signature validation processes to ensure that additional controls are in place to detect malformed signature attempts. The fix implemented in version 1.7.1 specifically addresses the length validation mechanisms in the compareBase64StringToRaw, DSIGAlgorithmHandlerDefault, and DSIGAlgorithmHandlerDefault::verify functions, restoring proper bounds checking and preventing the exploitation scenarios described in the vulnerability. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates across their infrastructure. This vulnerability aligns with CWE-129, which addresses improper validation of length values, and relates to ATT&CK technique T1059.007 for execution through signature validation bypass mechanisms that could enable further attack progression within compromised systems.