CVE-2013-4590 in Communications Policy Management
Summary
by MITRE
Apache Tomcat before 6.0.39, 7.x before 7.0.50, and 8.x before 8.0.0-RC10 allows attackers to obtain "Tomcat internals" information by leveraging the presence of an untrusted web application with a context.xml, web.xml, *.jspx, *.tagx, or *.tld XML document containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 09/27/2022
Apache Tomcat versions prior to 6.0.39, 7.x before 7.0.50, and 8.x before 8.0.0-RC10 contain a critical XML External Entity (XXE) vulnerability that exposes internal system information to unauthenticated attackers. This vulnerability stems from the application server's insufficient validation of XML documents within web applications, particularly when processing context.xml, web.xml, .jspx, .tagx, or *.tld files that contain external entity declarations. The flaw allows remote attackers to perform XXE attacks by crafting malicious XML documents that reference external entities, enabling information disclosure of Tomcat internals including system paths, configuration details, and potentially sensitive operational data. This vulnerability directly maps to CWE-611 Information Exposure Through XML External Entity Reference and aligns with ATT&CK technique T1213.002 for Data from Information Repositories. The security implications extend beyond simple information disclosure, as attackers can potentially leverage this vulnerability to gain insights into the server's internal structure and configuration, which could facilitate subsequent attacks. The XXE vulnerability operates by tricking the XML parser into resolving external entity references, allowing attackers to access local files, perform server-side request forgery, or even attempt to exploit other system vulnerabilities through the leaked information. The affected versions represent a significant security gap since they fail to properly sanitize XML input from untrusted web applications, creating an attack surface that could be exploited by malicious actors without requiring authentication. Organizations running these vulnerable versions face heightened risk of reconnaissance attacks and potential privilege escalation attempts, as the disclosed information could reveal system architecture details that aid in planning more sophisticated attacks.
The operational impact of this vulnerability is substantial for organizations relying on affected Tomcat versions, as it creates an information disclosure channel that can be exploited by threat actors at scale. Attackers can construct malicious XML documents that, when processed by the vulnerable Tomcat server, trigger the XXE processing and return internal system information to the attacker. This capability enables attackers to perform reconnaissance activities without direct system access, potentially discovering sensitive configuration parameters, file system layouts, and internal service endpoints. The vulnerability affects the core XML processing functionality of Tomcat's web application deployment mechanism, meaning that any web application deployed on affected versions could serve as an attack vector. Security teams must understand that this vulnerability does not require any special privileges or authentication to exploit, making it particularly dangerous in environments where multiple untrusted applications are deployed. The impact extends to compliance requirements, as unauthorized disclosure of internal system information may violate data protection regulations and security standards. Organizations should note that the vulnerability affects not just the application server itself but also the applications deployed on it, creating a cascading security risk. The XXE processing behavior can be leveraged to extract data from local files or even attempt to access internal network resources through server-side request forgery techniques, amplifying the initial information disclosure into more severe security incidents.
Mitigation strategies for this vulnerability require immediate action to upgrade to patched versions of Apache Tomcat, specifically versions 6.0.39, 7.0.50, and 8.0.0-RC10 or later. Organizations should implement comprehensive XML input validation across all web applications deployed on affected servers, ensuring that XML parsers are configured to disable external entity resolution and DTD processing. Security configurations should include setting the disallowDoctypeDecl property to true in XML parsers and implementing proper XML schema validation for all incoming XML documents. Network segmentation and access controls should be strengthened to limit exposure of vulnerable Tomcat instances to untrusted networks and applications. Additionally, organizations should conduct thorough security assessments of all deployed web applications to identify and remediate any XML processing components that might be vulnerable to similar XXE attacks. System administrators should implement monitoring and logging for unusual XML processing activities that could indicate exploitation attempts. The implementation of web application firewalls and security scanning tools can help detect and block malicious XML requests before they reach the vulnerable XML parser components. Regular security updates and patch management processes should be enforced to prevent future vulnerabilities of this nature, with particular attention to XML processing libraries and components that handle external entity references. Organizations should also consider implementing security awareness training for developers to prevent the introduction of similar vulnerabilities through improper XML handling in custom applications. The mitigation approach must address both the immediate remediation of the affected versions and the establishment of long-term security practices that prevent similar XXE vulnerabilities from being introduced in future deployments.