CVE-2015-0851 in XMLTooling-C
Summary
by MITRE
XMLTooling-C before 1.5.5, as used in OpenSAML-C and Shibboleth Service Provider (SP), does not properly handle integer conversion exceptions, which allows remote attackers to cause a denial of service (crash) via schema-invalid XML data.
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Analysis
by VulDB Data Team • 12/02/2024
The vulnerability identified as CVE-2015-0851 affects XMLTooling-C versions prior to 1.5.5, which are components integral to OpenSAML-C and Shibboleth Service Provider implementations. This flaw resides in the handling of XML schema validation processes where the software fails to properly manage integer conversion exceptions that occur during parsing of malformed XML data. The issue manifests when the system encounters schema-invalid XML content that contains improper integer values or conversions that cannot be processed correctly by the underlying XML parsing libraries.
The technical exploitation of this vulnerability occurs through carefully crafted XML data that contains invalid integer representations or malformed schema elements that trigger unhandled exceptions during the XML processing pipeline. When the XMLTooling-C library attempts to parse such invalid data, it encounters situations where integer conversion operations fail, but the exception handling mechanism is insufficient to gracefully manage these failures. This leads to abrupt termination of the application process, resulting in a denial of service condition that can be exploited remotely by attackers who can submit malicious XML payloads to the vulnerable system.
From an operational perspective this vulnerability represents a significant risk to identity management systems that rely on Shibboleth and OpenSAML implementations for single sign-on and federated identity services. The remote attack vector means that adversaries can exploit this weakness without requiring local access or authentication, making it particularly dangerous in production environments where these systems handle sensitive authentication traffic. The denial of service impact can disrupt access to critical applications and services, potentially affecting thousands of users who depend on the federated identity infrastructure.
The vulnerability maps to CWE-704 in the Common Weakness Enumeration catalog, which classifies it as a weakness related to improper handling of integer conversion exceptions. This weakness falls under the broader category of improper exception handling, where software fails to properly manage exceptional conditions that occur during normal processing operations. The attack surface extends across all systems utilizing Shibboleth SP or OpenSAML-C components that process external XML data without proper input validation and sanitization.
Mitigation strategies should focus on immediate patching of affected XMLTooling-C components to version 1.5.5 or later, which includes proper exception handling for integer conversion scenarios. Organizations should also implement robust XML input validation and sanitization measures, including the use of XML schema validation with strict error handling, and consider implementing rate limiting and monitoring for unusual XML processing patterns. Additionally, network-level protections such as XML firewalls or API gateways can provide additional layers of defense by filtering malicious XML content before it reaches the vulnerable components. The remediation process should also include comprehensive testing of the patched systems to ensure that the fix properly handles all edge cases in XML processing without introducing new vulnerabilities or performance degradation.