CVE-2013-2202 in WordPress
Summary
by MITRE
WordPress before 3.5.2 allows remote attackers to read arbitrary files via an oEmbed XML provider response 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 • 01/03/2022
WordPress versions prior to 3.5.2 contained a critical vulnerability that enabled remote attackers to perform arbitrary file reads through a flaw in the oEmbed XML provider response handling mechanism. This vulnerability represented a classic XML External Entity (XXE) issue that exploited how WordPress processed external entity declarations within XML responses. The flaw occurred when WordPress encountered XML content containing external entity declarations that referenced local files on the server through entity references, allowing attackers to access sensitive files that should have remained protected.
The technical implementation of this vulnerability relied on the improper sanitization of XML content within WordPress's oEmbed functionality. When WordPress received XML responses from external providers, it failed to properly validate or restrict the processing of external entities, enabling attackers to craft malicious XML payloads that would trigger file inclusion operations. The vulnerability specifically targeted the XML parser's handling of entity references, where an attacker could define an external entity that pointed to a local file path and then reference that entity within the XML structure. This created a path traversal scenario where the XML parser would resolve the entity reference and effectively read the contents of the specified file from the server's filesystem.
The operational impact of this vulnerability was significant as it allowed attackers to access arbitrary files on the WordPress server, potentially exposing sensitive data including configuration files, database credentials, user information, and application source code. Attackers could leverage this vulnerability to gain unauthorized access to critical system information that could be used for further exploitation or to compromise the entire WordPress installation. The vulnerability was particularly dangerous because it could be exploited through legitimate oEmbed functionality that many WordPress sites used to embed content from external sources, making it difficult to detect and prevent.
This vulnerability aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and represents a common pattern in web application security flaws where XML parsers are not properly configured to disable external entity processing. The attack vector demonstrated in CVE-2013-2202 corresponds to techniques documented in the ATT&CK framework under T1213 (Data from Information Repositories) and T1566 (Phishing with Social Engineering) as attackers could use this vulnerability to harvest sensitive information from compromised systems. The vulnerability also relates to broader XXE attack patterns that have been consistently identified in web application security assessments and are commonly categorized under the OWASP Top Ten as a critical security risk. Organizations running vulnerable WordPress installations were at risk of data breaches and system compromise, with the attack requiring minimal technical expertise to execute successfully.
The recommended mitigations for this vulnerability included upgrading to WordPress version 3.5.2 or later, which contained proper XML entity validation and sanitization measures. Additionally, administrators should implement proper input validation for all XML content, disable external entity processing in XML parsers, and consider implementing web application firewalls to detect and block suspicious XML content. The vulnerability highlighted the importance of proper XML processing configuration and served as a reminder of the critical need for input validation and sanitization in web applications. Organizations should also conduct regular security assessments to identify similar vulnerabilities in other XML processing components and ensure that all third-party integrations properly handle external entity references.