Summary
A high-severity OS command injection vulnerability in the Tenda W18E web management server allows shell commands to be incorporated into packet-capture operations. An authenticated user may exploit improperly validated JSON fields, while devices in a factory-reset state may expose the same risk without authentication.
A high-severity OS command injection vulnerability in the Tenda W18E web management server allows shell commands to be incorporated into packet-capture operations. An authenticated user may exploit improperly validated JSON fields, while devices in a factory-reset state may expose the same risk without authentication.
Affected context
The vulnerability occurs in the Tenda W18E web management server's authenticated
"diagnose" packet-capture feature. It is present when values from JSON fields such
as protocol or targetDevice are insufficiently validated before being incorporated
into a tcpdump command. The exposure may be broader when the device is operating
in a factory-reset state.
The vulnerability occurs in the Tenda W18E web management server's authenticated
"diagnose" packet-capture feature. It is present when values from JSON fields such
as protocol or targetDevice are insufficiently validated before being incorporated
into a tcpdump command. The exposure may be broader when the device is operating
in a factory-reset state.
Exploit preconditions
- Attack surface: Web management server and its packet-capture diagnostic feature
- Required access: Normally authenticated web-management access; factory-reset devices may not require authentication
- Trigger point: Processing a diagnostic request containing attacker-controlled JSON field values
- Why exploitation is possible: Input is incorporated into a shell command without adequate separation from command syntax, and the resulting process runs with root privileges
- Attack surface: Web management server and its packet-capture diagnostic feature
- Required access: Normally authenticated web-management access; factory-reset devices may not require authentication
- Trigger point: Processing a diagnostic request containing attacker-controlled JSON field values
- Why exploitation is possible: Input is incorporated into a shell command without adequate separation from command syntax, and the resulting process runs with root privileges
Why this happens
The underlying defect is command construction from insufficiently trusted input.
Values from JSON fields are concatenated into a shell command rather than being treated
strictly as data or passed through a safe argument-handling interface. This permits
command syntax to influence execution, mapping to CWE-78: Improper Neutralization of Special Elements used in an OS Command.
The underlying defect is command construction from insufficiently trusted input.
Values from JSON fields are concatenated into a shell command rather than being treated
strictly as data or passed through a safe argument-handling interface. This permits
command syntax to influence execution, mapping to CWE-78: Improper Neutralization of Special Elements used in an OS Command.
Potential impact
- An attacker may execute arbitrary operating-system commands
- Device configuration, credentials, or network settings could be accessed or altered
- The router may be fully compromised because the command executes with root privileges
- Network traffic could be monitored, disrupted, or redirected
- The device could be used to affect connected systems or participate in further attacks
- An attacker may execute arbitrary operating-system commands
- Device configuration, credentials, or network settings could be accessed or altered
- The router may be fully compromised because the command executes with root privileges
- Network traffic could be monitored, disrupted, or redirected
- The device could be used to affect connected systems or participate in further attacks
General mitigation guidance
Mitigation generally focuses on removing shell interpretation from diagnostic workflows
and reducing the trust placed in management requests.
Common defensive patterns include:
- Invoke diagnostic utilities through a process API that passes fixed argument arrays rather than constructing shell command strings
- Apply strict allowlists and type validation to protocol, device, and interface-related fields
- Reject unexpected characters, delimiters, and values before command construction
- Require authentication and authorization for diagnostic operations in every device state
- Run diagnostic processes with the lowest practical privileges and restrict their capabilities
- Separate management-plane input handling from privileged system operations
- Use secure-by-default factory-reset behavior that does not expose administrative functionality
Mitigation generally focuses on removing shell interpretation from diagnostic workflows
and reducing the trust placed in management requests.
Common defensive patterns include:
- Invoke diagnostic utilities through a process API that passes fixed argument arrays rather than constructing shell command strings
- Apply strict allowlists and type validation to protocol, device, and interface-related fields
- Reject unexpected characters, delimiters, and values before command construction
- Require authentication and authorization for diagnostic operations in every device state
- Run diagnostic processes with the lowest practical privileges and restrict their capabilities
- Separate management-plane input handling from privileged system operations
- Use secure-by-default factory-reset behavior that does not expose administrative functionality
How teams detect issues like this
Detection approaches may include:
- Static analysis rules for shell execution APIs, command-string concatenation, and user-controlled values reaching process invocation
- Code review checks for JSON fields used in diagnostic, networking, or system utility commands
- Runtime monitoring for unusual management requests and unexpected child processes launched by the web server
- Policy enforcement requiring allowlisted command arguments and non-shell process execution
- Automated security review tools that trace request parameters into privileged command execution
Detection approaches may include:
- Static analysis rules for shell execution APIs, command-string concatenation, and user-controlled values reaching process invocation
- Code review checks for JSON fields used in diagnostic, networking, or system utility commands
- Runtime monitoring for unusual management requests and unexpected child processes launched by the web server
- Policy enforcement requiring allowlisted command arguments and non-shell process execution
- Automated security review tools that trace request parameters into privileged command execution
Sources
| Source | Link |
|---|---|
| cushz. | cushz.github.io/ |
