CVE-2017-15893 in File Station
Summary
by MITRE
Directory traversal vulnerability in the SYNO.FileStation.Extract in Synology File Station before 1.1.1-0099 allows remote authenticated users to write arbitrary files via the dest_folder_path parameter.
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Analysis
by VulDB Data Team • 01/17/2023
The vulnerability identified as CVE-2017-15893 represents a critical directory traversal flaw within Synology File Station's SYNO.FileStation.Extract component. This security weakness affects versions prior to 1.1.1-0099 and enables authenticated remote attackers to manipulate file system operations through malicious input manipulation. The vulnerability specifically targets the dest_folder_path parameter, which controls where extracted files are placed within the system's directory structure. Attackers can exploit this flaw to write arbitrary files to locations outside of intended directories, potentially leading to unauthorized file system modifications and system compromise. The issue stems from insufficient input validation and sanitization within the file extraction process, allowing malicious path sequences to bypass normal access controls and directory restrictions.
This directory traversal vulnerability falls under the CWE-22 category, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw operates by allowing attackers to manipulate file paths through the dest_folder_path parameter, enabling them to navigate beyond the intended directory boundaries. The vulnerability is classified as a remote authenticated attack vector, meaning that an attacker must first establish valid credentials to exploit the weakness, but once authenticated, they can perform file system operations that should normally be restricted. The security implications extend beyond simple file manipulation, as this vulnerability could potentially enable attackers to overwrite critical system files, inject malicious content, or establish persistent access points within the affected system.
The operational impact of CVE-2017-15893 is substantial for organizations utilizing Synology File Station services, particularly those with multiple user accounts or shared file systems. An attacker who successfully exploits this vulnerability can potentially compromise the integrity of the file system by writing files to arbitrary locations, including system directories or other users' file spaces. This capability could lead to privilege escalation scenarios, where attackers gain elevated access rights through manipulation of system files or configuration data. The vulnerability also presents risks for data integrity and confidentiality, as unauthorized file modifications could result in data corruption, information disclosure, or complete system compromise. Organizations relying on Synology products for file storage and sharing operations face significant exposure when this vulnerability remains unpatched, as it represents a fundamental weakness in the system's file access controls and path validation mechanisms.
Mitigation strategies for CVE-2017-15893 primarily focus on immediate patch deployment and enhanced input validation measures. The most effective solution involves updating to Synology File Station version 1.1.1-0099 or later, which includes proper path validation and sanitization controls to prevent directory traversal attacks. Organizations should implement comprehensive access control measures, including principle of least privilege enforcement, where users have minimal necessary permissions for file operations. Network segmentation and monitoring should be enhanced to detect suspicious file system activity, particularly around directory creation and file writing operations. Additionally, implementing web application firewalls and input validation rules can provide additional defense layers against path traversal attempts. The vulnerability demonstrates the critical importance of proper input validation and access control mechanisms in file system operations, aligning with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1078.004 for Valid Accounts - Default Accounts, as attackers may leverage authenticated sessions to exploit these weaknesses. Regular security audits and vulnerability assessments should be conducted to identify similar path traversal vulnerabilities in other system components, as this type of flaw commonly exists in file handling functions across various software platforms.