CVE-2017-8809 in MediaWiki
Summary
by MITRE
api.php in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 has a Reflected File Download vulnerability.
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Analysis
by VulDB Data Team • 01/23/2021
The vulnerability identified as CVE-2017-8809 represents a critical reflected file download flaw in MediaWiki's api.php component affecting multiple version branches. This vulnerability falls under the CWE-434 category of Unrestricted Upload of File with Dangerous Type, which is a well-documented weakness in web application security. The issue enables attackers to manipulate the application's behavior by injecting malicious file references that are subsequently downloaded and executed by unsuspecting users. The vulnerability exists in the way MediaWiki processes user input through the api.php endpoint, specifically when handling certain parameters that control file download operations.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL containing a file reference that appears legitimate to the victim's browser. When a user clicks on such a link, the MediaWiki application reflects the attacker-controlled file path back to the user agent, which then attempts to download and execute the specified file. This creates a scenario where users are unknowingly prompted to download potentially malicious files, including executables, scripts, or other harmful content. The reflected nature of the vulnerability means that the malicious input is immediately reflected in the application's response without proper sanitization or validation, making it particularly dangerous in web environments where user interaction is common.
The operational impact of this vulnerability extends beyond simple file download manipulation and represents a significant risk to organizational security infrastructure. Attackers can leverage this weakness to distribute malware, phishing payloads, or other malicious content to users within the MediaWiki environment. The vulnerability is particularly concerning because it affects multiple versions of MediaWiki, including the stable releases 1.27.4, 1.28.3, and 1.29.2, meaning that a substantial number of organizations using MediaWiki could be vulnerable. The attack vector typically involves social engineering tactics where users are tricked into clicking malicious links, potentially compromising entire user bases within the wiki environment. This vulnerability can be categorized under the ATT&CK technique T1193 - Spearphishing Attachment, as it enables attackers to deliver malicious payloads through compromised wiki systems.
Organizations should implement immediate mitigations including updating to the patched versions of MediaWiki that address this vulnerability, specifically versions 1.27.4, 1.28.3, and 1.29.2. Network-level protections such as web application firewalls should be configured to monitor and block suspicious file download patterns, particularly those involving unexpected file types or unusual download parameters. Input validation mechanisms should be strengthened to ensure that all user-supplied parameters are properly sanitized before being processed by the api.php endpoint. Security teams should also conduct thorough audits of their MediaWiki installations to identify any custom configurations or extensions that might exacerbate the vulnerability. Additionally, user education programs should be implemented to raise awareness about suspicious links and the importance of verifying file sources before downloading content. The vulnerability demonstrates the critical importance of maintaining up-to-date software versions and implementing comprehensive security controls to prevent reflected file download attacks in web applications.