CVE-2013-6955 in DiskStation Manager
Summary
by MITRE
webman/imageSelector.cgi in Synology DiskStation Manager (DSM) 4.0 before 4.0-2259, 4.2 before 4.2-3243, and 4.3 before 4.3-3810 Update 1 allows remote attackers to append data to arbitrary files, and consequently execute arbitrary code, via a pathname in the SLICEUPLOAD X-TMP-FILE HTTP header.
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Analysis
by VulDB Data Team • 04/19/2025
The vulnerability identified as CVE-2013-6955 resides within the webman module of Synology DiskStation Manager (DSM) versions prior to specific update releases. This flaw exists in the imageSelector.cgi component which processes file operations through HTTP headers, specifically the SLICEUPLOAD X-TMP-FILE header that dictates temporary file handling during image upload processes. The vulnerability represents a critical security flaw that allows remote attackers to manipulate file paths and append data to arbitrary files on the system, ultimately enabling arbitrary code execution capabilities. The affected versions include DSM 4.0 before 4.0-2259, DSM 4.2 before 4.2-3243, and DSM 4.3 before 4.3-3810 Update 1, indicating this was a widespread issue affecting multiple major releases of the Synology operating system.
The technical implementation of this vulnerability stems from improper input validation and path manipulation within the imageSelector.cgi script. When the SLICEUPLOAD X-TMP-FILE HTTP header is processed, the application fails to properly sanitize or validate the pathname contained within this header, allowing attackers to specify arbitrary file paths. This insufficient validation creates a path traversal condition where malicious users can manipulate the temporary file creation process to target system files or directories outside the intended scope. The vulnerability is classified as a path traversal attack pattern and aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability is severe and encompasses multiple attack vectors that can compromise the entire system. Remote attackers can leverage this flaw to append malicious data to critical system files, potentially overwriting configuration files, executables, or system binaries. This capability enables attackers to achieve persistent access and execute arbitrary code with the privileges of the web server process, typically running as a privileged user. The attack scenario can lead to complete system compromise, data exfiltration, and unauthorized access to sensitive information stored on the network-attached storage device. The vulnerability's remote exploitability means that attackers do not require physical access or local credentials to exploit the flaw, making it particularly dangerous for network-attached storage systems that are often exposed to external networks.
Mitigation strategies for CVE-2013-6955 require immediate implementation of software updates provided by Synology to address the specific vulnerability in the webman module. Organizations should ensure that all DSM installations are updated to versions 4.0-2259, 4.2-3243, or 4.3-3810 Update 1 respectively, which contain patches that properly validate and sanitize the SLICEUPLOAD X-TMP-FILE header. Additionally, network administrators should implement firewall rules to restrict access to the affected DSM web management interface, particularly when the system is exposed to untrusted networks. The implementation of web application firewalls and intrusion detection systems can help monitor for exploitation attempts targeting this specific vulnerability. From a defensive perspective, this vulnerability demonstrates the importance of input validation and proper file handling practices, aligning with ATT&CK technique T1059 for command and scripting interpreter and T1566 for credential access through network attacks, emphasizing the need for comprehensive security controls that address both application-level and network-level protections.