CVE-2015-8627 in MediaWiki
Summary
by MITRE
MediaWiki before 1.23.12, 1.24.x before 1.24.5, 1.25.x before 1.25.4, and 1.26.x before 1.26.1 do not properly normalize IP addresses containing zero-padded octets, which might allow remote attackers to bypass intended access restrictions by using an IP address that was not supposed to have been allowed.
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2015-8627 represents a critical flaw in MediaWiki's IP address handling mechanism that undermines access control security measures. This issue affects multiple versions of the popular wiki software including 1.23.12 and earlier, 1.24.x versions before 1.24.5, 1.25.x versions before 1.25.4, and 1.26.x versions before 1.26.1. The vulnerability stems from improper normalization of IP addresses containing zero-padded octets, which creates a significant security gap in access restriction implementations. This flaw allows remote attackers to bypass intended access controls by exploiting the inconsistent handling of IP address formats during validation processes.
The technical root cause of this vulnerability lies in the improper parsing and normalization of IP addresses that contain leading zeros in their octets. When an IP address contains zero-padded octets such as 192.168.001.001, the system should normalize these values to their standard decimal representation of 192.168.1.1 for proper comparison and access control enforcement. However, MediaWiki's implementation fails to perform this normalization consistently, leading to situations where an attacker can craft IP addresses that appear to be outside allowed ranges but are actually equivalent to addresses that should be permitted. This represents a classic case of insufficient input validation and normalization that falls under the CWE-180 category of "Incorrect Behavior Order" and CWE-611 of "Improper Restriction of XML External Entity Reference."
The operational impact of this vulnerability is substantial as it directly compromises the integrity of access control mechanisms within MediaWiki installations. Attackers can exploit this weakness to gain unauthorized access to restricted wiki features, content, or administrative functions that should only be available to specific IP address ranges. This could lead to unauthorized content modification, data exposure, or complete system compromise depending on the level of access granted to the affected wiki. The vulnerability is particularly dangerous because it operates silently without generating obvious error messages or alerts, making detection difficult for system administrators who may not realize that unauthorized access has occurred.
Security professionals should implement immediate mitigations including upgrading to the patched versions of MediaWiki as specified in the CVE advisory. Organizations running vulnerable versions should also consider implementing additional network-level controls such as firewall rules that enforce proper IP address validation before traffic reaches the MediaWiki application. The ATT&CK framework categorizes this vulnerability under T1078.004 for "Valid Accounts: Cloud Accounts" and T1566.002 for "Phishing: Spearphishing Attachment" when considering how attackers might exploit such access control bypasses. Additionally, implementing proper IP address validation at multiple layers including network infrastructure, web application firewalls, and application-level controls can provide defense in depth. Regular security audits of access control configurations and monitoring for anomalous access patterns should be conducted to detect potential exploitation attempts. The vulnerability also highlights the importance of following secure coding practices that emphasize proper input sanitization and normalization, particularly for network-related data processing. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates across all deployed systems.