CVE-2018-0503 in MediaWiki
Summary
by MITRE
Mediawiki 1.31 before 1.31.1, 1.30.1, 1.29.3 and 1.27.5 contains a flaw where contrary to the documentation, $wgRateLimits entry for 'user' overrides that for 'newbie'.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-0503 affects MediaWiki versions prior to 1.31.1, 1.30.1, 1.29.3, and 1.27.5, representing a critical configuration flaw in the rate limiting system that directly contradicts documented behavior. This issue resides within the MediaWiki core software that powers numerous wikis including Wikipedia, where rate limiting serves as a fundamental security mechanism to prevent abuse and ensure system stability. The flaw specifically impacts the $wgRateLimits configuration parameter which is designed to enforce different rate limits for various user groups based on their privileges and experience levels.
The technical implementation of this vulnerability stems from a misconfiguration in how MediaWiki processes rate limiting rules for different user categories. According to the documented behavior, the 'newbie' user group should have more restrictive rate limits compared to regular 'user' accounts, as new users are typically more susceptible to abuse or spam activities. However, the implementation bug causes the rate limit configuration for 'user' entries to override the settings for 'newbie' entries, effectively weakening the security controls for less experienced users. This creates a scenario where new users can perform actions at rates that should be restricted, while experienced users maintain their intended limitations.
From an operational perspective, this vulnerability significantly undermines the security posture of MediaWiki installations by allowing potential attackers or malicious users to exploit the rate limiting system for unauthorized activities. The impact extends beyond simple abuse prevention as it affects the integrity of user experience management and system resource allocation. Attackers could potentially flood the system with requests, create spam content, or perform automated attacks that would normally be constrained by the newbie user rate limits. This vulnerability particularly affects wikis that rely heavily on user contributions and community moderation, as it compromises the effectiveness of the system's built-in abuse prevention mechanisms.
The flaw aligns with CWE-691, which addresses inadequate protection mechanisms in software systems, and represents a specific instance of improper privilege management where configuration overrides fail to maintain intended security boundaries. From an ATT&CK framework perspective, this vulnerability could be leveraged during the privilege escalation and resource consumption phases, allowing adversaries to perform actions that would normally be restricted. Organizations using affected MediaWiki versions face increased risk of spam attacks, denial of service scenarios, and potential data integrity issues. The vulnerability demonstrates how seemingly minor configuration issues can have significant security implications, particularly in collaborative platforms where user access controls are critical for maintaining system stability and content quality.
Mitigation strategies should focus on immediate patching to the affected MediaWiki versions, ensuring that administrators review and properly configure their $wgRateLimits settings to maintain the intended user group distinctions. Security teams should implement monitoring for unusual activity patterns that might indicate exploitation attempts, while also considering additional rate limiting measures beyond the core system. Organizations should conduct thorough configuration reviews to verify that rate limiting rules are properly enforced according to documented behavior, and maintain awareness of similar issues in other MediaWiki components that might present analogous security concerns.