Summary
A critical command-injection vulnerability in the TOTOLINK A950RG device-information handler allows attacker-controlled MAC address data to reach an operating-system command context. Because the affected handler is remotely reachable, an attacker may execute unauthorized commands on the router when the vulnerable processing path is exposed.
A critical command-injection vulnerability in the TOTOLINK A950RG device-information handler allows attacker-controlled MAC address data to reach an operating-system command context. Because the affected handler is remotely reachable, an attacker may execute unauthorized commands on the router when the vulnerable processing path is exposed.
Affected context
The vulnerability affects TOTOLINK A950RG firmware deployments where the device-information handler processes MAC address input while reading or interpreting data associated with /var/lib/misc/udhcpd.leases. Risk is increased when the handler is reachable over an exposed network interface and does not isolate or safely pass user-controlled values to system commands.
The vulnerability affects TOTOLINK A950RG firmware deployments where the device-information handler processes MAC address input while reading or interpreting data associated with /var/lib/misc/udhcpd.leases. Risk is increased when the handler is reachable over an exposed network interface and does not isolate or safely pass user-controlled values to system commands.
Exploit preconditions
- Attack surface: The remotely accessible device-information handler
- Required access: Network reachability to the affected router service; authentication requirements depend on the device's access controls
- Trigger point: Processing of attacker-controlled MAC address data by
getDeviceInfo - Why exploitation is possible: The input can influence an operating-system command context without adequate separation between data and command syntax
- Attack surface: The remotely accessible device-information handler
- Required access: Network reachability to the affected router service; authentication requirements depend on the device's access controls
- Trigger point: Processing of attacker-controlled MAC address data by
getDeviceInfo - Why exploitation is possible: The input can influence an operating-system command context without adequate separation between data and command syntax
Why this happens
The underlying issue is command injection caused by incorporating externally controlled input into operating-system command execution. When a MAC address or related value is treated as trusted command content rather than as data, shell or command-interpreter metacharacters may alter the intended operation. 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 class.
The underlying issue is command injection caused by incorporating externally controlled input into operating-system command execution. When a MAC address or related value is treated as trusted command content rather than as data, shell or command-interpreter metacharacters may alter the intended operation. 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 class.
Potential impact
- An attacker may execute unauthorized commands on the router
- Router configuration or operational data could be altered
- Network traffic could be disrupted, redirected, or monitored
- The device could be used for lateral movement or additional attacks
- Compromise could affect connected systems and services
- An attacker may execute unauthorized commands on the router
- Router configuration or operational data could be altered
- Network traffic could be disrupted, redirected, or monitored
- The device could be used for lateral movement or additional attacks
- Compromise could affect connected systems and services
General mitigation guidance
Mitigation generally focuses on ensuring that external input remains data throughout processing and cannot become command syntax.
Common defensive patterns include:
- Avoiding shell invocation when a direct library or system API is available
- Passing arguments through structured process-execution interfaces rather than shell strings
- Applying strict allowlist validation for MAC address formats before use
- Separating input validation from command construction and enforcing validation at trust boundaries
- Running device services with the minimum privileges required
- Limiting management interfaces to trusted networks and applying authentication and authorization controls
Mitigation generally focuses on ensuring that external input remains data throughout processing and cannot become command syntax.
Common defensive patterns include:
- Avoiding shell invocation when a direct library or system API is available
- Passing arguments through structured process-execution interfaces rather than shell strings
- Applying strict allowlist validation for MAC address formats before use
- Separating input validation from command construction and enforcing validation at trust boundaries
- Running device services with the minimum privileges required
- Limiting management interfaces to trusted networks and applying authentication and authorization controls
How teams detect issues like this
Detection can include static analysis for shell execution APIs that receive request parameters, string concatenation, or formatted command arguments. Code review should examine handlers that process MAC addresses, lease data, or other network-derived values before invoking system utilities. Runtime monitoring can look for unexpected child processes, anomalous command execution, and changes to lease or configuration data. CI and policy checks may require allowlist validation and prohibit shell-based execution for externally influenced values.
Detection can include static analysis for shell execution APIs that receive request parameters, string concatenation, or formatted command arguments. Code review should examine handlers that process MAC addresses, lease data, or other network-derived values before invoking system utilities. Runtime monitoring can look for unexpected child processes, anomalous command execution, and changes to lease or configuration data. CI and policy checks may require allowlist validation and prohibit shell-based execution for externally influenced values.
Sources
| Source | Link |
|---|---|
| gist. | gist.github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| totolink. | totolink.net/ |
