CVE-2015-5730 in WordPress
Summary
by MITRE
The sanitize_widget_instance function in wp-includes/class-wp-customize-widgets.php in WordPress before 4.2.4 does not use a constant-time comparison for widgets, which allows remote attackers to conduct a timing side-channel attack by measuring the delay before inequality is calculated.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 06/07/2022
The vulnerability identified as CVE-2015-5730 resides within the WordPress content management system and specifically affects versions prior to 4.2.4. This issue is classified as a timing side-channel attack vector that exploits the sanitize_widget_instance function located in the wp-includes/class-wp-customize-widgets.php file. The flaw represents a critical security weakness that undermines the integrity of WordPress's widget customization functionality and exposes systems to sophisticated remote exploitation techniques.
The technical implementation of this vulnerability stems from the improper handling of string comparisons within the widget sanitization process. When WordPress processes widget instances through the sanitize_widget_instance function, it fails to employ constant-time comparison algorithms for verifying widget data integrity. This deviation from secure coding practices allows attackers to measure the time differences required to process different input values, thereby enabling them to infer sensitive information about the system's internal state. The vulnerability specifically targets the comparison operations that occur during widget instance validation, where attackers can observe timing variations that correlate with the comparison outcomes.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with a method to conduct sophisticated timing attacks against WordPress installations. Remote adversaries can leverage this weakness to perform credential guessing, extract sensitive configuration data, or gain unauthorized access to widget management interfaces. The timing side-channel attack technique exploits the fact that different string comparisons take varying amounts of time depending on the position of the first differing character, creating measurable delays that can be analyzed to reconstruct the target data. This vulnerability particularly affects WordPress installations that utilize the customizer functionality for widget management, making it a significant concern for organizations relying on these features.
Security professionals should note that this vulnerability aligns with CWE-208, which describes timing side-channel attacks, and can be categorized under ATT&CK technique T1212 for the exploitation of timing attacks. The issue represents a classic example of how seemingly minor implementation flaws can create substantial security risks in web applications. Organizations should prioritize immediate patching of affected WordPress installations to address this vulnerability, as the timing variations can be detected and exploited with relatively simple tools. The recommended mitigation strategy involves upgrading to WordPress version 4.2.4 or later, which implements proper constant-time comparison algorithms to prevent the leakage of information through timing variations.
The broader implications of this vulnerability highlight the importance of secure coding practices in web application development, particularly when handling sensitive data comparisons. This flaw demonstrates how cryptographic and security-related functions must be implemented with careful attention to timing characteristics to prevent side-channel information leakage. System administrators and security teams should consider implementing additional monitoring for unusual timing patterns in their WordPress installations, as well as conducting regular security assessments to identify similar vulnerabilities in custom plugins or themes that may utilize similar comparison functions. The vulnerability serves as a reminder that even minor coding oversights in security-sensitive functions can have significant consequences for system integrity and user data protection.