Summary
A command injection vulnerability in the TOTOLINK A950RG UploadCustomModule function allows attacker-controlled FileMd5 input to influence command execution. Because the affected function is reachable remotely, an attacker who can access the relevant interface may execute operating-system commands with the device's privileges.
A command injection vulnerability in the TOTOLINK A950RG UploadCustomModule function allows attacker-controlled FileMd5 input to influence command execution. Because the affected function is reachable remotely, an attacker who can access the relevant interface may execute operating-system commands with the device's privileges.
Affected context
The vulnerability occurs in TOTOLINK A950RG firmware version 4.1.2cu.5268_B20221104, within the UploadCustomModule function of lib/cste_modules/product.so. Risk is present when the remotely reachable module-upload workflow accepts the FileMd5 argument and incorporates it into command processing without sufficiently separating data from shell syntax.
The vulnerability occurs in TOTOLINK A950RG firmware version 4.1.2cu.5268_B20221104, within the UploadCustomModule function of lib/cste_modules/product.so. Risk is present when the remotely reachable module-upload workflow accepts the FileMd5 argument and incorporates it into command processing without sufficiently separating data from shell syntax.
Exploit preconditions
- Attack surface: The device's remotely reachable custom-module upload interface
- Required access: Network access to the exposed interface; authentication requirements are deployment-dependent and are not established by the available description
- Trigger point: Processing of the FileMd5 argument by UploadCustomModule
- Why exploitation is possible: The argument is insufficiently constrained before being used in a command-execution context, allowing input to alter the intended command structure
- Attack surface: The device's remotely reachable custom-module upload interface
- Required access: Network access to the exposed interface; authentication requirements are deployment-dependent and are not established by the available description
- Trigger point: Processing of the FileMd5 argument by UploadCustomModule
- Why exploitation is possible: The argument is insufficiently constrained before being used in a command-execution context, allowing input to alter the intended command structure
Why this happens
The underlying bug is improper neutralization of special elements in an operating-system command. Input supplied through FileMd5 is treated as trusted command data rather than as a strictly validated value, allowing attacker-controlled content to affect command interpretation. This maps primarily to CWE-77, Command Injection, and is also related to CWE-74, Improper Neutralization of Special Elements in Output Used by a Downstream Component.
The underlying bug is improper neutralization of special elements in an operating-system command. Input supplied through FileMd5 is treated as trusted command data rather than as a strictly validated value, allowing attacker-controlled content to affect command interpretation. This maps primarily to CWE-77, Command Injection, and is also related to CWE-74, Improper Neutralization of Special Elements in Output Used by a Downstream Component.
Potential impact
- An attacker may execute arbitrary operating-system commands on the router
- The device could be taken over or its configuration could be altered
- Network traffic, credentials, or stored data could be exposed
- The router could be used for persistence, service disruption, or attacks against other systems
- Compromised devices could contribute to botnet or broader network activity
- An attacker may execute arbitrary operating-system commands on the router
- The device could be taken over or its configuration could be altered
- Network traffic, credentials, or stored data could be exposed
- The router could be used for persistence, service disruption, or attacks against other systems
- Compromised devices could contribute to botnet or broader network activity
General mitigation guidance
Mitigation generally centers on removing shell interpretation from module
processing and reducing trust in request parameters.
Common defensive patterns include:
- Prefer direct APIs, fixed argument arrays, or library calls instead of invoking a shell
- Apply strict allowlist validation for FileMd5 values, such as enforcing the expected format and length
- Reject unexpected characters and normalize input before any downstream processing
- Ensure upload and module-management interfaces require appropriate authentication and authorization
- Run related services with the least privileges needed for their function
- Segment device-management interfaces from untrusted networks and limit administrative exposure
- Add regression tests covering metacharacters, malformed values, and boundary conditions
Mitigation generally centers on removing shell interpretation from module
processing and reducing trust in request parameters.
Common defensive patterns include:
- Prefer direct APIs, fixed argument arrays, or library calls instead of invoking a shell
- Apply strict allowlist validation for FileMd5 values, such as enforcing the expected format and length
- Reject unexpected characters and normalize input before any downstream processing
- Ensure upload and module-management interfaces require appropriate authentication and authorization
- Run related services with the least privileges needed for their function
- Segment device-management interfaces from untrusted networks and limit administrative exposure
- Add regression tests covering metacharacters, malformed values, and boundary conditions
How teams detect issues like this
Organizations can look for this vulnerability class through:
- Static analysis rules that identify request data reaching system, shell, or process-spawning APIs
- Code review searches for string concatenation or interpolation involving FileMd5-like parameters
- Review of native-library wrappers and firmware handlers that construct external commands
- Runtime monitoring for unexpected child processes, command interpreters, or unusual outbound connections from the device
- Network policy alerts for access to management and upload endpoints from untrusted segments
- Automated security scanning and software composition review integrated into firmware development workflows
Organizations can look for this vulnerability class through:
- Static analysis rules that identify request data reaching system, shell, or process-spawning APIs
- Code review searches for string concatenation or interpolation involving FileMd5-like parameters
- Review of native-library wrappers and firmware handlers that construct external commands
- Runtime monitoring for unexpected child processes, command interpreters, or unusual outbound connections from the device
- Network policy alerts for access to management and upload endpoints from untrusted segments
- Automated security scanning and software composition review integrated into firmware development workflows
Sources
| Source | Link |
|---|---|
| gist. | gist.github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| totolink. | totolink.net/ |
