Summary
A critical command injection vulnerability in the DrayTek Vigor2960 Upload Endpoint allows crafted input submitted to the uploadlangs function to influence operating-system command execution. Because the endpoint is remotely reachable, an attacker who can access it may execute commands with the privileges of the affected web service.
A critical command injection vulnerability in the DrayTek Vigor2960 Upload Endpoint allows crafted input submitted to the uploadlangs function to influence operating-system command execution. Because the endpoint is remotely reachable, an attacker who can access it may execute commands with the privileges of the affected web service.
Affected context
The vulnerability affects Vigor2960 devices running the identified legacy firmware and involves the uploadlangs function in /cgi-bin/mainfunction.cgi. Risk is greatest when the upload endpoint is network-accessible and fails to isolate uploaded or otherwise user-controlled values from operating-system command construction. The product is no longer generally supported, which may limit the availability of future security fixes.
The vulnerability affects Vigor2960 devices running the identified legacy firmware and involves the uploadlangs function in /cgi-bin/mainfunction.cgi. Risk is greatest when the upload endpoint is network-accessible and fails to isolate uploaded or otherwise user-controlled values from operating-system command construction. The product is no longer generally supported, which may limit the availability of future security fixes.
Exploit preconditions
- Attack surface: The remotely accessible Upload Endpoint exposed through the device's web interface
- Required access: Network reachability to the endpoint; authentication requirements may depend on the device's configuration and deployment
- Trigger point: Processing of attacker-influenced input by the
uploadlangsfunction - Why exploitation is possible: Untrusted values can reach command-processing logic without sufficient separation from operating-system command syntax
- Attack surface: The remotely accessible Upload Endpoint exposed through the device's web interface
- Required access: Network reachability to the endpoint; authentication requirements may depend on the device's configuration and deployment
- Trigger point: Processing of attacker-influenced input by the
uploadlangsfunction - Why exploitation is possible: Untrusted values can reach command-processing logic without sufficient separation from operating-system command syntax
Why this happens
The underlying bug is command injection, where externally controlled input is incorporated into an operating-system command or command-like operation without reliable separation, validation, or safe argument handling. This maps primarily to CWE-77: Improper Neutralization of Special Elements used in a Command, with CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component describing the broader injection pattern. The insecure design treats data from an upload-related request as trusted command input.
The underlying bug is command injection, where externally controlled input is incorporated into an operating-system command or command-like operation without reliable separation, validation, or safe argument handling. This maps primarily to CWE-77: Improper Neutralization of Special Elements used in a Command, with CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component describing the broader injection pattern. The insecure design treats data from an upload-related request as trusted command input.
Potential impact
- An attacker may execute arbitrary commands on the affected device
- The device may be compromised or reconfigured
- Network traffic may be monitored, redirected, or disrupted
- Stored credentials, configuration data, or other sensitive information could be exposed
- The compromised device could be used for lateral movement or additional attacks
- An attacker may execute arbitrary commands on the affected device
- The device may be compromised or reconfigured
- Network traffic may be monitored, redirected, or disrupted
- Stored credentials, configuration data, or other sensitive information could be exposed
- The compromised device could be used for lateral movement or additional attacks
General mitigation guidance
Mitigation generally focuses on removing shell interpretation from upload processing and reducing trust in request-controlled values.
Common defensive patterns include:
- Prefer direct process APIs with fixed executables and structured argument arrays over shell command construction
- Apply strict allowlists for filenames, language identifiers, and other accepted upload metadata
- Enforce type, length, encoding, and format validation before processing
- Keep uploaded content in isolated, non-executable locations and avoid deriving commands from its contents
- Run the web service with the minimum filesystem, process, and network privileges required
- Restrict management interfaces and upload endpoints to trusted administrative networks where feasible
- Replace unsupported components with maintained software that receives security updates
Mitigation generally focuses on removing shell interpretation from upload processing and reducing trust in request-controlled values.
Common defensive patterns include:
- Prefer direct process APIs with fixed executables and structured argument arrays over shell command construction
- Apply strict allowlists for filenames, language identifiers, and other accepted upload metadata
- Enforce type, length, encoding, and format validation before processing
- Keep uploaded content in isolated, non-executable locations and avoid deriving commands from its contents
- Run the web service with the minimum filesystem, process, and network privileges required
- Restrict management interfaces and upload endpoints to trusted administrative networks where feasible
- Replace unsupported components with maintained software that receives security updates
How teams detect issues like this
Detection can combine source analysis, runtime monitoring, and deployment policy controls:
- Use static analysis rules to identify shell invocation, command concatenation, interpolation, or execution APIs receiving request or upload data
- Review code paths from CGI parameters and file metadata into process-spawning or system-command functions
- Monitor web and device logs for unusual requests to the upload endpoint, repeated failures, unexpected language or filename values, and command-process activity
- Apply policies that prohibit shell execution for untrusted input and require approved argument-handling APIs
- Use automated code review and software composition analysis tools to flag command-injection patterns and unsupported network appliances
Detection can combine source analysis, runtime monitoring, and deployment policy controls:
- Use static analysis rules to identify shell invocation, command concatenation, interpolation, or execution APIs receiving request or upload data
- Review code paths from CGI parameters and file metadata into process-spawning or system-command functions
- Monitor web and device logs for unusual requests to the upload endpoint, repeated failures, unexpected language or filename values, and command-process activity
- Apply policies that prohibit shell execution for untrusted input and require approved argument-handling APIs
- Use automated code review and software composition analysis tools to flag command-injection patterns and unsupported network appliances
