CVE-2016-10330 in Photo Station
Summary
by MITRE
Directory traversal vulnerability in synophoto_dsm_user, a SUID program, as used in Synology Photo Station before 6.5.3-3226 allows local users to write to arbitrary files via unspecified vectors.
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Analysis
by VulDB Data Team • 09/25/2020
The vulnerability identified as CVE-2016-10330 represents a critical directory traversal flaw within the synophoto_dsm_user component of Synology Photo Station software. This SUID (Set User ID) program operates with elevated privileges, creating a significant attack surface that can be exploited by local users to gain unauthorized access to system resources. The vulnerability exists in Synology Photo Station versions prior to 6.5.3-3226, where the program fails to properly validate file paths during operations, allowing malicious input to traverse directory boundaries and access restricted files or directories. The SUID mechanism, which is designed to provide temporary elevated privileges for specific operations, becomes a vector for privilege escalation when combined with improper input sanitization. This flaw specifically affects the synophoto_dsm_user binary that handles user authentication and photo processing functions within the Synology DSM (DiskStation Manager) ecosystem.
The technical exploitation of this vulnerability occurs through unspecified vectors that manipulate file path handling within the SUID program. Local attackers can craft malicious input that bypasses normal file access controls, enabling them to write data to arbitrary locations on the filesystem. The vulnerability stems from inadequate input validation and path traversal checks within the program's file handling routines. When the synophoto_dsm_user binary processes user requests, it fails to properly sanitize user-supplied paths, allowing attackers to inject directory traversal sequences such as "../" or similar patterns that can navigate beyond intended directories. This weakness aligns with CWE-22 - Improper Limitation of a Pathname to a Restricted Directory, which is commonly exploited in privilege escalation scenarios. The SUID nature of the program means that any successful exploitation grants the attacker elevated privileges equivalent to the program's owner, typically root or a high-privilege system user.
The operational impact of this vulnerability extends beyond simple file access violations, as it enables local privilege escalation and persistent system compromise. Attackers can leverage this vulnerability to modify critical system files, install backdoors, or establish persistent access to the device. The implications are particularly severe for network-attached storage (NAS) devices like Synology DSM systems, where local access often translates to broader network compromise. Once an attacker achieves elevated privileges through this directory traversal flaw, they can manipulate photo databases, modify user accounts, or access sensitive system configuration files. The vulnerability also increases the risk of lateral movement within network environments where Synology devices serve as central storage points. From an ATT&CK framework perspective, this vulnerability maps to T1068 - Exploitation for Privilege Escalation and T1548.001 - Abuse Elevation Control Mechanism, as it exploits the SUID mechanism to elevate privileges without requiring additional authentication. The attack chain typically involves local system access followed by privilege escalation through the vulnerable SUID program.
Mitigation strategies for CVE-2016-10330 focus on both immediate remediation and long-term security hardening. The primary solution involves upgrading to Synology Photo Station version 6.5.3-3226 or later, which includes proper input validation and path traversal protections. System administrators should also implement the principle of least privilege by reviewing and minimizing the use of SUID programs where possible. Additional defensive measures include regular security audits of SUID binaries, monitoring for unauthorized modifications to system files, and implementing file integrity monitoring solutions. Network segmentation and access controls should be enforced to limit local access to sensitive systems. The vulnerability highlights the importance of proper input validation in privileged programs and demonstrates how seemingly minor flaws in path handling can lead to significant security breaches. Organizations should also consider implementing application whitelisting policies and regular vulnerability assessments to identify similar issues in other SUID programs or system components. Security teams should monitor for exploitation attempts through log analysis and implement automated alerts for suspicious file access patterns that could indicate directory traversal attempts.