CVE-2017-15895 in Router Manager
Summary
by MITRE
Directory traversal vulnerability in the SYNO.FileStation.Extract in Synology Router Manager (SRM) before 1.1.5-6542-4 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-2017-15895 represents a critical directory traversal flaw within Synology Router Manager's SYNO.FileStation.Extract component, affecting versions prior to 1.1.5-6542-4. This directory traversal vulnerability specifically manifests through the dest_folder_path parameter, enabling authenticated remote attackers to manipulate file system operations beyond their intended scope. The flaw resides in the improper validation of user-supplied input parameters, allowing malicious actors to craft requests that can write files to arbitrary locations on the system. This vulnerability is particularly concerning as it operates within a router management interface, which typically has elevated privileges and access to sensitive network infrastructure components. The security implications extend beyond simple file system manipulation, as the ability to write arbitrary files can lead to privilege escalation, persistent backdoors, or complete system compromise. The vulnerability affects the core file extraction functionality of the router management system, which is designed to handle compressed file operations for network administrators. Attackers can exploit this weakness by submitting maliciously crafted dest_folder_path values that contain directory traversal sequences such as ../ or ..\, which bypass normal access controls and allow writing files to locations outside the intended extraction directory. This vulnerability directly maps to CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The attack vector requires authentication, meaning that an attacker must first obtain valid credentials to exploit the vulnerability, but once authenticated, the impact can be severe due to the privileged nature of the router management interface. The operational impact of this vulnerability is significant as it allows attackers to potentially overwrite critical system files, install malicious software, or create persistent access points within the network infrastructure. The flaw demonstrates a classic lack of input sanitization and proper access control enforcement, where the application fails to validate that the destination path remains within the expected boundaries. Synology Router Manager serves as a critical network management tool that provides administrators with access to various router functions including file management, network configuration, and system monitoring. The vulnerability compromises the integrity of this management interface, potentially allowing attackers to gain unauthorized access to sensitive network configurations or manipulate the router's file system in ways that could disrupt network services or provide persistent access to the network infrastructure. The affected version range indicates this was a relatively recent vulnerability in the product lifecycle, suggesting that the flaw had been present for some time before the patch was released. From an operational security perspective, this vulnerability aligns with ATT&CK technique T1059.007, which involves the use of command and scripting interpreter, as attackers could potentially leverage the file writing capability to deploy malicious scripts or binaries. The vulnerability also relates to T1078.004, which covers valid accounts with elevated privileges, since the exploitation requires authentication to the router management system. Network administrators should be particularly concerned about this vulnerability as it can be exploited from outside the network perimeter if proper access controls are not in place, potentially allowing remote attackers to compromise network infrastructure. The patch release for version 1.1.5-6542-4 addressed the input validation issues by implementing proper path sanitization and ensuring that all destination paths are validated against a whitelist of allowed directories. Organizations should immediately update their Synology Router Manager installations to the patched version and review access controls to ensure that only authorized personnel have access to the management interface. The vulnerability serves as a reminder of the importance of proper input validation, particularly in applications that handle file system operations, and highlights the need for robust access controls in network management systems. Security monitoring should include detection of unusual file system activity patterns that might indicate exploitation attempts, and network segmentation should be implemented to limit access to critical management interfaces. This vulnerability demonstrates how seemingly simple path traversal flaws can have significant impacts when present in privileged network management applications, emphasizing the need for comprehensive security testing and regular patch management procedures. The issue also underscores the importance of principle of least privilege in network infrastructure management, where even authenticated users should be restricted to appropriate file system access based on their role requirements.