CVE-2013-2153 in XML Security for C++
Summary
by MITRE
The XML digital signature functionality (xsec/dsig/DSIGReference.cpp) in Apache Santuario XML Security for C++ (aka xml-security-c) before 1.7.1 allows context-dependent attackers to reuse signatures and spoof arbitrary content via crafted Reference elements in the Signature, aka "XML Signature Bypass issue."
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Analysis
by VulDB Data Team • 01/04/2022
The vulnerability identified as CVE-2013-2153 represents a critical weakness in Apache Santuario XML Security for C++ library versions prior to 1.7.1, specifically affecting the XML digital signature functionality. This flaw exists within the DSIGReference.cpp component and enables attackers to exploit a fundamental security mechanism designed to ensure data integrity and authenticity. The issue stems from improper validation of Reference elements within XML signatures, creating a pathway for malicious actors to manipulate digital signatures without detection. The vulnerability operates at the intersection of cryptographic security and XML processing, where the signature validation process fails to properly verify the relationships between referenced data and the signature itself.
The technical implementation flaw manifests when the XML signature processing engine does not adequately enforce the integrity constraints that should prevent reference reuse attacks. Attackers can craft malicious Reference elements that appear valid to the parser but contain manipulated URI references or altered canonicalization methods. This allows them to reuse existing signatures against different content, effectively bypassing the security controls that digital signatures are designed to provide. The vulnerability is context-dependent, meaning it requires specific conditions to be exploited, typically involving scenarios where the same signature might be legitimately applied to different documents or where the signature validation process does not properly verify the reference integrity. This weakness directly violates the core principles of digital signature security and can be categorized under CWE-347, which addresses improper verification of cryptographic signatures, and aligns with ATT&CK technique T1556.004 related to credential access through manipulation of digital certificates and signatures.
The operational impact of this vulnerability extends beyond simple data integrity concerns to potentially compromise entire security architectures that rely on XML signatures for authentication and authorization. Systems using vulnerable versions of xml-security-c may experience unauthorized access, data tampering, or spoofing attacks where malicious actors can present forged documents as legitimate. The vulnerability particularly affects applications that process XML documents containing digital signatures, including web services, enterprise integration platforms, and security infrastructure components. Organizations utilizing these systems face risks of supply chain attacks, where compromised signatures could be used to validate malicious software or manipulate critical business processes. The attack vector requires the ability to modify XML documents before they are processed by the vulnerable library, making it particularly dangerous in environments where document processing occurs in untrusted or partially trusted contexts. Remediation efforts must include immediate patching of affected systems to version 1.7.1 or later, along with comprehensive security assessments of existing signature validation processes and potential signature revocation where appropriate.
The broader implications of this vulnerability highlight the importance of robust signature validation mechanisms in XML security implementations. Security practitioners should implement additional layers of validation beyond the basic signature verification, including content integrity checks, proper URI validation, and monitoring for unusual signature reuse patterns. The vulnerability serves as a reminder of the complexity involved in implementing secure cryptographic protocols and the critical need for thorough security testing of security libraries. Organizations should also consider implementing signature auditing mechanisms to detect potential exploitation attempts and establish incident response procedures specifically tailored to signature-related security incidents. This vulnerability demonstrates that even well-established security libraries can contain critical flaws that can be exploited by attackers with sufficient technical knowledge and access to the target environment.