Summary
Beganovich snappdf contains an OS command injection vulnerability on Windows because attacker-influenced rendered URL data can reach command execution without adequate escaping. Under conditions where an attacker can control the value passed to setUrl(), command syntax may be interpreted by the PHP process, potentially allowing arbitrary command execution.
Beganovich snappdf contains an OS command injection vulnerability on Windows because attacker-influenced rendered URL data can reach command execution without adequate escaping. Under conditions where an attacker can control the value passed to setUrl(), command syntax may be interpreted by the PHP process, potentially allowing arbitrary command execution.
Affected context
The vulnerability occurs in Windows deployments of snappdf versions before 6.1.0 when a rendered URL or related setUrl() value can be influenced by an untrusted party. The affected execution path passes that value to executeOnWindows(), which invokes PHP exec() without sufficiently separating URL data from operating-system command syntax.
The vulnerability occurs in Windows deployments of snappdf versions before 6.1.0 when a rendered URL or related setUrl() value can be influenced by an untrusted party. The affected execution path passes that value to executeOnWindows(), which invokes PHP exec() without sufficiently separating URL data from operating-system command syntax.
Exploit preconditions
- Attack surface: URL rendering and Windows command execution - Required access: Ability to influence the value supplied to setUrl(), either
directly or through an application feature that constructs the rendered URL
- Trigger point: Processing the attacker-influenced URL through the Windows
execution path
- Why exploitation is possible: Untrusted input reaches a shell command
context without adequate argument isolation or metacharacter handling
- Attack surface: URL rendering and Windows command execution - Required access: Ability to influence the value supplied to setUrl(), either
directly or through an application feature that constructs the rendered URL
- Trigger point: Processing the attacker-influenced URL through the Windows
execution path
- Why exploitation is possible: Untrusted input reaches a shell command
context without adequate argument isolation or metacharacter handling
Why this happens
The underlying bug is command construction from attacker-controlled input. executeOnWindows() passes a value derived from setUrl() to PHP exec() without applying a safe command-building strategy or ensuring that the value is treated strictly as data. This behavior maps to CWE-78, where externally influenced input can alter the structure of an operating-system command.
The underlying bug is command construction from attacker-controlled input. executeOnWindows() passes a value derived from setUrl() to PHP exec() without applying a safe command-building strategy or ensuring that the value is treated strictly as data. This behavior maps to CWE-78, where externally influenced input can alter the structure of an operating-system command.
Potential impact
- An attacker may execute arbitrary commands with the privileges of the PHP process.
- The application environment could be modified or compromised.
- Confidential files or rendered content may be accessed.
- Malware, persistence mechanisms, or additional tooling could be introduced.
- A compromised process could be used for lateral movement, depending on its permissions and network access.
- An attacker may execute arbitrary commands with the privileges of the PHP process.
- The application environment could be modified or compromised.
- Confidential files or rendered content may be accessed.
- Malware, persistence mechanisms, or additional tooling could be introduced.
- A compromised process could be used for lateral movement, depending on its permissions and network access.
General mitigation guidance
Mitigation generally focuses on removing shell interpretation from the URL rendering workflow. Secure-by-default patterns include avoiding shell commands for process invocation where library or direct API alternatives exist, passing arguments through APIs that preserve argument boundaries, and treating URLs as data rather than command fragments. Input trust should be reduced through strict URL parsing, allowlisted schemes and destinations, canonical validation, and rejection of unexpected control characters. The PHP process and any helper processes should run with least privilege, restricted filesystem access, limited network permissions, and appropriate isolation.
Mitigation generally focuses on removing shell interpretation from the URL rendering workflow. Secure-by-default patterns include avoiding shell commands for process invocation where library or direct API alternatives exist, passing arguments through APIs that preserve argument boundaries, and treating URLs as data rather than command fragments. Input trust should be reduced through strict URL parsing, allowlisted schemes and destinations, canonical validation, and rejection of unexpected control characters. The PHP process and any helper processes should run with least privilege, restricted filesystem access, limited network permissions, and appropriate isolation.
How teams detect issues like this
Detection can include static analysis for flows from URL setters, request parameters, or rendered content into exec(), shell invocation APIs, or dynamically constructed command strings. Code review should look for string concatenation in process commands, missing argument boundary controls, and platform-specific execution branches that handle Windows metacharacters inconsistently. Runtime monitoring can alert on unexpected child processes created by the PHP service, while policy enforcement can require approved process-launch APIs and security review for shell execution. Automated security review tools may help identify these data flows.
Detection can include static analysis for flows from URL setters, request parameters, or rendered content into exec(), shell invocation APIs, or dynamically constructed command strings. Code review should look for string concatenation in process commands, missing argument boundary controls, and platform-specific execution branches that handle Windows metacharacters inconsistently. Runtime monitoring can alert on unexpected child processes created by the PHP service, while policy enforcement can require approved process-launch APIs and security review for shell execution. Automated security review tools may help identify these data flows.
