@mobilenext/mobile-mcp Path Traversal Vulnerability

The @mobilenext/mobile-mcp npm package, versions prior to 0.0.49, contains a critical path traversal vulnerability. This flaw stems from the mobile_save_screenshot and mobile_start_screen_recording tools which improperly handle user-supplied paths. Specifically, the saveTo parameter in mobile_save_screenshot and the output parameter in mobile_start_screen_recording are passed directly to filesystem write operations without adequate validation. This oversight enables a malicious actor to write arbitrary files to locations outside of the intended workspace. A successful exploit of this vulnerability allows for the potential overwriting of sensitive system files, enabling privilege escalation and persistence on the host system.

Attack Chain

1. An attacker gains control over the saveTo or output parameter of the vulnerable functions. This could be achieved through a malicious application, supply chain attack, or other means of code injection.
2. The attacker crafts a path containing traversal sequences (e.g., ../) designed to navigate outside of the intended save directory.
3. The attacker calls the mobile_save_screenshot or mobile_start_screen_recording tool with the manipulated path as the saveTo or output parameter, respectively.
4. The vulnerable function passes the attacker-controlled path to fs.writeFileSync() without validation.
5. fs.writeFileSync() writes the screenshot or screen recording data to the attacker-specified path.
6. If the path leads to a sensitive system file (e.g., ~/.bashrc, ~/.ssh/authorized_keys), it is overwritten with the contents of the screenshot or screen recording.
7. The attacker can overwrite configuration files or executables in order to achieve code execution.
8. The attacker achieves persistence and/or elevated privileges on the system.

Impact

Successful exploitation of this path traversal vulnerability can have severe consequences. An attacker can overwrite critical system files, such as shell configuration files (.bashrc, .zshrc), SSH authorized keys (.ssh/authorized_keys), or application configuration files. This can lead to arbitrary code execution, privilege escalation, and persistent backdoor access to the affected system. The reported impact includes potential for a broken shell and unauthorized access. All users of @mobilenext/mobile-mcp versions prior to 0.0.49 are vulnerable.

Recommendation

• Upgrade to @mobilenext/mobile-mcp version 0.0.49 or later to remediate the vulnerability.
• Implement robust input validation for all file paths used in file system operations. Specifically, validate the saveTo and output parameters of the mobile_save_screenshot and mobile_start_screen_recording functions.
• Deploy the Sigma rule “Detect Mobile-MCP Path Traversal Attempts” to your SIEM to detect attempts to exploit this vulnerability.
• Monitor application logs for unusual file access patterns or attempts to write to sensitive system directories.