CVE-2014-3963 in ownCloud
Summary
by MITRE
ownCloud Server before 6.0.1 does not properly check permissions, which allows remote authenticated users to access arbitrary preview pictures via unspecified vectors.
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Analysis
by VulDB Data Team • 03/10/2019
The vulnerability identified as CVE-2014-3963 affects ownCloud Server versions prior to 6.0.1 and represents a critical authorization flaw that undermines the platform's access control mechanisms. This issue stems from insufficient permission validation within the preview picture functionality, creating a pathway for authenticated attackers to bypass intended security restrictions. The vulnerability manifests when users with legitimate accounts attempt to access preview images that should be restricted based on their access rights, demonstrating a fundamental breakdown in the application's privilege enforcement model.
The technical implementation of this vulnerability resides in the preview generation and access control logic within ownCloud's file handling system. When users request preview images for files they have access to, the application should verify that the requesting user possesses appropriate permissions to view both the file and its associated preview data. However, the flawed implementation fails to adequately validate these permissions, allowing attackers to construct requests that retrieve preview pictures belonging to other users or files they should not be able to access. This weakness operates at the intersection of improper access control and inadequate input validation, creating a scenario where user-provided parameters can be manipulated to traverse expected access boundaries.
The operational impact of this vulnerability extends beyond simple data exposure, as it enables attackers to potentially gather sensitive information about other users' file collections and activities. An authenticated attacker could systematically access preview images from various files, potentially discovering file types, content patterns, and user behavior without proper authorization. This reconnaissance capability significantly weakens the overall security posture of the platform, as it provides attackers with valuable intelligence for further exploitation attempts. The vulnerability affects the confidentiality aspect of the CIA triad by enabling unauthorized data access, while also potentially compromising integrity if attackers can manipulate or correlate the retrieved preview information.
This vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems, and demonstrates characteristics consistent with ATT&CK technique T1078 for valid accounts and T1566 for social engineering. The flaw represents a classic case of insufficient access control validation where the system fails to properly enforce user permissions during preview operations. Organizations using affected versions of ownCloud face significant risks as attackers can leverage this vulnerability to perform unauthorized data reconnaissance and potentially identify sensitive files within the system. The attack vector requires only authenticated access, making it particularly concerning as it can be exploited by users who have legitimate accounts but lack proper privileges for the targeted resources.
Mitigation strategies for CVE-2014-3963 focus primarily on upgrading to ownCloud Server version 6.0.1 or later, which includes the necessary permission checks and access control improvements. System administrators should also implement additional monitoring to detect unusual access patterns related to preview requests, as well as review and validate existing user permissions to ensure proper access control enforcement. Organizations should consider implementing network-level controls to restrict access to preview functionality where possible, and conduct regular security assessments to identify similar authorization flaws in other applications. The vulnerability serves as a reminder of the critical importance of proper access control implementation and the need for thorough security testing of file handling and preview generation features in web applications.