CVE-2016-1500 in ownCloud
Summary
by MITRE
ownCloud Server before 7.0.12, 8.0.x before 8.0.10, 8.1.x before 8.1.5, and 8.2.x before 8.2.2, when the "file_versions" application is enabled, does not properly check the return value of getOwner, which allows remote authenticated users to read the files with names starting with ".v" and belonging to a sharing user by leveraging an incoming share.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/01/2025
The vulnerability identified as CVE-2016-1500 affects ownCloud Server versions prior to specific patch releases, creating a critical access control flaw within the file_versions application. This vulnerability exists when the file_versions feature is enabled, which is a core component designed to maintain file version history for users. The flaw stems from improper validation of the getOwner function's return value, a critical security mechanism that should verify file ownership before granting access. When this validation fails, it creates an exploitable condition that allows authenticated attackers to bypass normal file access controls.
The technical exploitation of this vulnerability occurs through a specific attack vector involving shared files and versioned files. Attackers can leverage incoming shares to access files that begin with the ".v" prefix, which are typically versioned files stored in the system. This prefix indicates that these files are part of the version control system, and normally should only be accessible to the file owner. However, due to the flawed return value checking, the system fails to properly validate whether the requesting user has legitimate access rights to these versioned files. The vulnerability specifically targets the file_versions application, which maintains historical versions of files shared with users.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it represents a significant compromise in the security model of the ownCloud platform. An authenticated attacker with access to shared files can potentially read sensitive data that should be restricted to the original file owner. This creates a scenario where users can access versioned files belonging to other users, potentially exposing confidential information, intellectual property, or personal data. The vulnerability is particularly concerning because it operates within the legitimate sharing and versioning workflows that users expect to function securely, making the attack less detectable and more insidious.
The root cause of this vulnerability can be categorized under CWE-284, which addresses improper access control mechanisms, and aligns with ATT&CK technique T1078 for Valid Accounts and T1566 for Phishing. The flaw demonstrates a classic case of insufficient input validation where the system fails to properly verify ownership permissions before granting access to versioned files. Security practitioners should note that this vulnerability affects multiple version streams of ownCloud, requiring patch management across several release branches. The recommended mitigation involves updating to the patched versions 7.0.12, 8.0.10, 8.1.5, and 8.2.2 respectively, which implement proper return value validation for the getOwner function. Organizations should also consider implementing additional monitoring for file access patterns and versioned file operations to detect potential exploitation attempts.