Summary
Pheditor contains an OS command injection flaw in its terminal action handler that allows shell metacharacters in the dir POST parameter to bypass command whitelisting.
When an authenticated user can reach the terminal feature, they may execute arbitrary OS commands with web server privileges, leading to full remote code execution.
Pheditor contains an OS command injection flaw in its terminal action handler that allows shell metacharacters in the dir POST parameter to bypass command whitelisting.
When an authenticated user can reach the terminal feature, they may execute arbitrary OS commands with web server privileges, leading to full remote code execution.
Affected context
This vulnerability occurs in Pheditor deployments that expose the terminal feature to authenticated users.
It manifests when user-supplied input from the dir POST parameter is passed into shell execution without robust sanitization or strict argument handling.
Environments where Pheditor runs with elevated or broad filesystem privileges are particularly exposed, though the risk depends on how accessible the terminal endpoint is and what the web server account can access.
This vulnerability occurs in Pheditor deployments that expose the terminal feature to authenticated users.
It manifests when user-supplied input from the dir POST parameter is passed into shell execution without robust sanitization or strict argument handling.
Environments where Pheditor runs with elevated or broad filesystem privileges are particularly exposed, though the risk depends on how accessible the terminal endpoint is and what the web server account can access.
Exploit preconditions
- Attack surface: HTTP endpoint implementing the terminal action handler inside Pheditor.
- Required access: Valid authenticated access to Pheditor with permission to invoke the terminal feature.
- Trigger point: Submission of crafted data in the
dirPOST parameter that includes shell metacharacters or command chaining syntax. - Why exploitation is possible: The terminal action handler incorporates user-controlled
dirvalues into an OS command without safely constraining them to a non-executable argument context, effectively bypassing the intended TERMINAL_COMMANDS whitelist.
- Attack surface: HTTP endpoint implementing the terminal action handler inside Pheditor.
- Required access: Valid authenticated access to Pheditor with permission to invoke the terminal feature.
- Trigger point: Submission of crafted data in the
dirPOST parameter that includes shell metacharacters or command chaining syntax. - Why exploitation is possible: The terminal action handler incorporates user-controlled
dirvalues into an OS command without safely constraining them to a non-executable argument context, effectively bypassing the intended TERMINAL_COMMANDS whitelist.
Why this happens
The underlying bug stems from building shell commands from user-controlled input and executing them via system-level APIs without proper neutralization of shell metacharacters.
Conceptually, this maps to CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where an application incorrectly assumes its whitelist or command wrapper is sufficient while still allowing untrusted data to influence the command line.
The insecure pattern is treating user input as a trusted command argument and relying on superficial whitelisting instead of strict, parameterized execution or non-shell-based invocation of filesystem operations.
The underlying bug stems from building shell commands from user-controlled input and executing them via system-level APIs without proper neutralization of shell metacharacters.
Conceptually, this maps to CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where an application incorrectly assumes its whitelist or command wrapper is sufficient while still allowing untrusted data to influence the command line.
The insecure pattern is treating user input as a trusted command argument and relying on superficial whitelisting instead of strict, parameterized execution or non-shell-based invocation of filesystem operations.
Potential impact
- Authenticated users could execute arbitrary OS commands on the server.
- Attackers may read, modify, or delete files accessible to the web server account.
- System integrity could be compromised through installation of backdoors or malware.
- The compromised host may be used as a pivot point for lateral movement within the infrastructure.
- Logs and configuration files can be altered to conceal activity or weaken future defenses.
- Authenticated users could execute arbitrary OS commands on the server.
- Attackers may read, modify, or delete files accessible to the web server account.
- System integrity could be compromised through installation of backdoors or malware.
- The compromised host may be used as a pivot point for lateral movement within the infrastructure.
- Logs and configuration files can be altered to conceal activity or weaken future defenses.
General mitigation guidance
Effective mitigation focuses on removing direct shell construction and reducing trust in user input that reaches command execution paths.
Secure patterns include:
- Avoid using shell-based execution for simple operations like directory listing; instead, call language-native APIs (e.g., PHP filesystem functions) that do not interpret shell metacharacters.
- If OS commands are unavoidable, use APIs that bypass the shell and pass arguments as discrete, validated parameters, ensuring user input cannot change the command structure.
- Apply strict validation and normalization to user-supplied path values, restricting them to expected formats and preventing directory traversal or special characters.
- Restrict which application features expose command-like behavior and apply least-privilege to the web server account so that, even if misused, it cannot access sensitive system areas.
- Design terminal-like interfaces as administrative-only tools with narrow, pre-defined actions rather than general-purpose command surfaces.
Effective mitigation focuses on removing direct shell construction and reducing trust in user input that reaches command execution paths.
Secure patterns include:
- Avoid using shell-based execution for simple operations like directory listing; instead, call language-native APIs (e.g., PHP filesystem functions) that do not interpret shell metacharacters.
- If OS commands are unavoidable, use APIs that bypass the shell and pass arguments as discrete, validated parameters, ensuring user input cannot change the command structure.
- Apply strict validation and normalization to user-supplied path values, restricting them to expected formats and preventing directory traversal or special characters.
- Restrict which application features expose command-like behavior and apply least-privilege to the web server account so that, even if misused, it cannot access sensitive system areas.
- Design terminal-like interfaces as administrative-only tools with narrow, pre-defined actions rather than general-purpose command surfaces.
How teams detect issues like this
Detection typically involves a combination of code-level and operational techniques:
- Static analysis rules that flag the use of shell execution functions (e.g.,
exec,shell_exec,system, backticks) when they incorporate user input or variable interpolation. - Code review heuristics that highlight places where path or command-related parameters are taken from HTTP request data and passed into OS-level operations.
- Security policies requiring that terminal or console features be treated as high-risk, subject to dedicated review and threat modeling before deployment.
- Runtime monitoring and logging of command execution patterns, looking for anomalous arguments, chained commands, or unexpected utilities being invoked from web-server processes.
- Integration of automated code scanning tools into CI pipelines to enforce policies around command construction and unsafe execution patterns.
Detection typically involves a combination of code-level and operational techniques:
- Static analysis rules that flag the use of shell execution functions (e.g.,
exec,shell_exec,system, backticks) when they incorporate user input or variable interpolation. - Code review heuristics that highlight places where path or command-related parameters are taken from HTTP request data and passed into OS-level operations.
- Security policies requiring that terminal or console features be treated as high-risk, subject to dedicated review and threat modeling before deployment.
- Runtime monitoring and logging of command execution patterns, looking for anomalous arguments, chained commands, or unexpected utilities being invoked from web-server processes.
- Integration of automated code scanning tools into CI pipelines to enforce policies around command construction and unsafe execution patterns.
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| github. | github.com/ |
