Summary
Netgate pfSense CE contains an OS command injection vulnerability in QinQ interface handling. An authenticated user with QinQ edit privilege may cause attacker-controlled interface data to be inserted into shell commands, which can result in command execution with root privileges.
Netgate pfSense CE contains an OS command injection vulnerability in QinQ interface handling. An authenticated user with QinQ edit privilege may cause attacker-controlled interface data to be inserted into shell commands, which can result in command execution with root privileges.
Affected context
The vulnerability occurs in pfSense CE deployments where an authenticated user has permission to edit QinQ configuration entries. Risk arises when a stored parent interface name is accepted without adequate validation and is later interpolated into ifconfig-related shell commands. The affected versions are reported as pfSense CE 2.7.0 through 2.9.0.
The vulnerability occurs in pfSense CE deployments where an authenticated user has permission to edit QinQ configuration entries. Risk arises when a stored parent interface name is accepted without adequate validation and is later interpolated into ifconfig-related shell commands. The affected versions are reported as pfSense CE 2.7.0 through 2.9.0.
Exploit preconditions
- Attack surface: QinQ configuration management and interface command generation
- Required access: An authenticated account with QinQ edit privilege
- Trigger point: Processing or editing a QinQ entry that uses the stored parent interface value
- Why exploitation is possible: The parent interface name is not sufficiently validated before being incorporated into a shell command executed with elevated privileges
- Attack surface: QinQ configuration management and interface command generation
- Required access: An authenticated account with QinQ edit privilege
- Trigger point: Processing or editing a QinQ entry that uses the stored parent interface value
- Why exploitation is possible: The parent interface name is not sufficiently validated before being incorporated into a shell command executed with elevated privileges
Why this happens
The underlying bug is an OS command injection flaw mapped to CWE-78. A value treated as an interface identifier is accepted from a privileged configuration workflow and later combined with shell command text without enforcing a strict allowed-value policy or using a command execution interface that separates arguments from shell syntax. As a result, data intended to represent a network interface can influence command interpretation.
The underlying bug is an OS command injection flaw mapped to CWE-78. A value treated as an interface identifier is accepted from a privileged configuration workflow and later combined with shell command text without enforcing a strict allowed-value policy or using a command execution interface that separates arguments from shell syntax. As a result, data intended to represent a network interface can influence command interpretation.
Potential impact
- An attacker may execute arbitrary operating-system commands.
- Commands could run with root-level privileges.
- The firewall configuration and network traffic controls could be altered.
- Sensitive system or network information could be accessed.
- The host could be used for persistence, lateral movement, or service disruption.
- An attacker may execute arbitrary operating-system commands.
- Commands could run with root-level privileges.
- The firewall configuration and network traffic controls could be altered.
- Sensitive system or network information could be accessed.
- The host could be used for persistence, lateral movement, or service disruption.
General mitigation guidance
Mitigation generally focuses on eliminating shell interpretation of
user-controlled configuration values.
Common defensive patterns include:
- Use direct process execution APIs that pass arguments separately rather than invoking a shell.
- Apply strict allowlisting for interface names and reject values outside the expected system-defined format.
- Validate and canonicalize values at both configuration-write and command-execution boundaries.
- Preserve least-privilege separation so network configuration operations do not expose unnecessary root capabilities.
- Restrict QinQ administration to trusted roles and reduce the number of accounts able to modify these settings.
- Treat stored configuration as untrusted until it has passed contextual validation.
Mitigation generally focuses on eliminating shell interpretation of
user-controlled configuration values.
Common defensive patterns include:
- Use direct process execution APIs that pass arguments separately rather than invoking a shell.
- Apply strict allowlisting for interface names and reject values outside the expected system-defined format.
- Validate and canonicalize values at both configuration-write and command-execution boundaries.
- Preserve least-privilege separation so network configuration operations do not expose unnecessary root capabilities.
- Restrict QinQ administration to trusted roles and reduce the number of accounts able to modify these settings.
- Treat stored configuration as untrusted until it has passed contextual validation.
How teams detect issues like this
Detection approaches may include:
- Static analysis rules for shell command construction involving configuration or request-derived values.
- Code review checks for string concatenation, interpolation, or formatting passed to shell execution APIs.
- Searches for network interface fields that are stored without allowlist validation and later reused in command builders.
- Runtime monitoring for unexpected ifconfig or related network utility invocations by management services.
- Policy enforcement requiring argument-separated process execution and validation of privileged command inputs.
- Automated security scanning and pull-request review tools that identify command injection patterns.
Detection approaches may include:
- Static analysis rules for shell command construction involving configuration or request-derived values.
- Code review checks for string concatenation, interpolation, or formatting passed to shell execution APIs.
- Searches for network interface fields that are stored without allowlist validation and later reused in command builders.
- Runtime monitoring for unexpected ifconfig or related network utility invocations by management services.
- Policy enforcement requiring argument-separated process execution and validation of privileged command inputs.
- Automated security scanning and pull-request review tools that identify command injection patterns.
