CVE-2015-6735 in TimedMediaHandler Extension
Summary
by MITRE
The reset functionality in the TimedMediaHandler extension for MediaWiki does not create a new transcode, which allows remote attackers to cause a denial of service (transcode deletion) by resetting a transcode.
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Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-6735 resides within the TimedMediaHandler extension for MediaWiki, a widely deployed multimedia handling system used by numerous organizations and platforms for managing audio and video content. This extension provides functionality for transcoding media files into different formats and resolutions, making it a critical component in media-rich web environments. The issue specifically targets the reset functionality that is designed to handle transcoding processes, creating a significant security gap that can be exploited by remote attackers to disrupt service availability.
The technical flaw manifests in the reset mechanism of the TimedMediaHandler extension where the system fails to properly create a new transcode when a reset operation is initiated. Instead of generating a fresh transcoding process, the system performs an operation that effectively deletes existing transcode files while maintaining the appearance of normal operation. This design defect allows malicious actors to repeatedly trigger reset operations against transcode processes, resulting in the systematic removal of transcoded media files from the system. The vulnerability operates at the application level within the MediaWiki framework, leveraging the legitimate reset functionality to achieve unintended destructive outcomes.
The operational impact of this vulnerability extends beyond simple service disruption to create a comprehensive denial of service scenario that affects media availability and system integrity. When attackers exploit this weakness, they can systematically delete transcode files from the media repository, rendering previously processed audio and video content inaccessible to legitimate users. This affects not only the immediate availability of media resources but also impacts system performance as the platform must repeatedly attempt to regenerate content that has been deleted. The vulnerability particularly affects environments where MediaWiki serves as a central media repository for large-scale deployments such as educational institutions, news organizations, and content management systems that rely heavily on multimedia functionality.
From a cybersecurity perspective, this vulnerability aligns with CWE-400, which addresses improper handling of resource exhaustion conditions, and represents a specific case of denial of service through resource manipulation. The attack pattern corresponds to techniques described in the ATT&CK framework under the T1499.004 subtechnique, which focuses on endpoint denial of service through resource exhaustion. The vulnerability demonstrates how legitimate system functionality can be weaponized to create cascading effects that compromise system availability and user experience. Organizations running affected MediaWiki installations face potential data loss scenarios and service degradation that can significantly impact their content delivery capabilities and user engagement metrics.
Mitigation strategies for CVE-2015-6735 require immediate attention through patching the TimedMediaHandler extension to properly implement reset functionality that creates new transcodes rather than deleting existing ones. System administrators should implement monitoring solutions to detect unusual reset patterns and establish automated alerts for suspicious transcode deletion activities. Network-level controls including rate limiting and access controls can help prevent automated exploitation attempts. Additionally, organizations should consider implementing backup strategies for transcoded media files and establish procedures for rapid recovery from transcode deletion events. The vulnerability underscores the importance of thorough code review processes for extension functionality and proper input validation in media processing systems to prevent similar issues from occurring in the future.