CVE-2007-0233 in WordPress
Summary
by MITRE
wp-trackback.php in WordPress 2.0.6 and earlier does not properly unset variables when the input data includes a numeric parameter with a value matching an alphanumeric parameter s hash value, which allows remote attackers to execute arbitrary SQL commands via the tb_id parameter. NOTE: it could be argued that this vulnerability is due to a bug in the unset PHP command (CVE-2006-3017) and the proper fix should be in PHP; if so, then this should not be treated as a vulnerability in WordPress.
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Analysis
by VulDB Data Team • 08/17/2024
The vulnerability described in CVE-2007-0233 represents a critical SQL injection flaw within WordPress version 2.0.6 and earlier, specifically within the wp-trackback.php file. This issue arises from improper variable handling during the trackback processing functionality, which is commonly used for notifying other blogs when content is referenced or linked to. The flaw manifests when the system processes input parameters where a numeric tb_id parameter matches the hash value of an alphanumeric s parameter, creating a condition where variables are not properly unset, thereby leaving them accessible to malicious input.
The technical exploitation of this vulnerability occurs through the manipulation of trackback parameters in the WordPress system's trackback mechanism. When an attacker crafts a malicious request containing both numeric and alphanumeric parameters where their hash values collide, the system fails to properly unset the variables as intended. This variable leakage creates an opportunity for SQL injection attacks, allowing remote attackers to execute arbitrary SQL commands against the WordPress database. The vulnerability specifically targets the tb_id parameter processing within the trackback functionality, which is designed to handle references from other weblogs to the current blog's content.
The operational impact of this vulnerability extends beyond simple data theft, as it enables full database compromise and potential system takeover. Attackers can leverage this flaw to extract sensitive information including user credentials, blog content, and potentially gain administrative access to the WordPress installation. The vulnerability affects not just individual blog installations but could be exploited at scale across multiple WordPress sites, particularly those running vulnerable versions. The issue demonstrates how improper variable handling in PHP applications can create persistent security weaknesses that remain undetected until exploited by malicious actors.
This vulnerability aligns with CWE-121, which describes the weakness of insufficient variable initialization or improper cleanup of variables, and relates to the broader category of injection flaws in the CWE taxonomy. The ATT&CK framework categorizes this under the T1190 technique of Exploit Public-Facing Application, as it targets the web application interface of WordPress. The vulnerability also connects to the broader PHP security landscape, particularly the PHP bug CVE-2006-3017 which relates to the unset command behavior, though the primary responsibility lies with WordPress for not implementing proper safeguards against such edge cases in their variable handling.
Mitigation strategies for this vulnerability include immediate upgrade to WordPress version 2.1 or later, which contains the proper fix for this variable handling issue. Organizations should also implement proper input validation and sanitization measures, particularly for trackback parameters, and consider implementing web application firewalls to detect and block suspicious trackback requests. Regular security audits of PHP applications should include examination of variable handling patterns and proper unset operations. Additionally, system administrators should disable trackback functionality if it's not required, as this eliminates the attack surface entirely. The incident underscores the importance of proper variable management in PHP applications and the need for comprehensive security testing that includes edge case scenarios involving parameter collisions and variable scoping issues.