Summary
The image_optimizer Ruby gem contains an OS command injection vulnerability in its image-format identification logic. When the gem processes an attacker-controlled image path with the identify option enabled, crafted path data may cause arbitrary commands to run with the privileges of the Ruby process.
The image_optimizer Ruby gem contains an OS command injection vulnerability in its image-format identification logic. When the gem processes an attacker-controlled image path with the identify option enabled, crafted path data may cause arbitrary commands to run with the privileges of the Ruby process.
Affected context
The vulnerability occurs in applications using image_optimizer versions 1.3.0 through 1.9.0 when the identify option is enabled and image paths can be influenced by an untrusted party. Common exposure scenarios may include uploaded files, user-supplied filenames, or other paths that reach ImageOptimizer#identify_format without adequate neutralization.
The vulnerability occurs in applications using image_optimizer versions 1.3.0 through 1.9.0 when the identify option is enabled and image paths can be influenced by an untrusted party. Common exposure scenarios may include uploaded files, user-supplied filenames, or other paths that reach ImageOptimizer#identify_format without adequate neutralization.
Exploit preconditions
- Attack surface: Image processing functionality that invokes ImageOptimizer#identify_format
- Required access: Ability to influence an image path or uploaded file name
- Trigger point: Image-format identification while the identify option is enabled
- Why exploitation is possible: The path is incorporated into a shell command executed through Ruby backtick syntax, allowing shell metacharacters in untrusted input to alter command interpretation
- Attack surface: Image processing functionality that invokes ImageOptimizer#identify_format
- Required access: Ability to influence an image path or uploaded file name
- Trigger point: Image-format identification while the identify option is enabled
- Why exploitation is possible: The path is incorporated into a shell command executed through Ruby backtick syntax, allowing shell metacharacters in untrusted input to alter command interpretation
Why this happens
The underlying bug is the construction and execution of a shell command using attacker-influenced path data without reliable argument separation or shell-safe handling. Ruby backticks invoke a command shell, so special characters in the supplied path can be interpreted as shell syntax rather than ordinary filename content. This behavior maps to CWE-78: Improper Neutralization of Special Elements used in an OS Command, commonly known as OS command injection.
The underlying bug is the construction and execution of a shell command using attacker-influenced path data without reliable argument separation or shell-safe handling. Ruby backticks invoke a command shell, so special characters in the supplied path can be interpreted as shell syntax rather than ordinary filename content. This behavior maps to CWE-78: Improper Neutralization of Special Elements used in an OS Command, commonly known as OS command injection.
Potential impact
- An attacker may execute arbitrary operating-system commands
- The application process and its accessible files may be compromised
- Sensitive data may be disclosed or modified
- Application credentials or service tokens could be exposed
- The host or surrounding services may be affected, depending on process privileges and isolation
- An attacker may execute arbitrary operating-system commands
- The application process and its accessible files may be compromised
- Sensitive data may be disclosed or modified
- Application credentials or service tokens could be exposed
- The host or surrounding services may be affected, depending on process privileges and isolation
General mitigation guidance
Mitigation generally focuses on removing shell interpretation from image-processing workflows and reducing trust in file paths.
Common defensive patterns include:
- Use direct process-execution APIs with separate argument arrays instead of shell command construction
- Treat uploaded filenames and paths as untrusted data
- Generate server-side filenames and resolve files against controlled directories
- Apply strict path validation, canonicalization, and allowlisting where appropriate
- Disable optional external identification behavior when it is not required
- Run image-processing workers with least privilege and restricted filesystem access
- Limit network, credential, and operating-system permissions available to the Ruby process
Mitigation generally focuses on removing shell interpretation from image-processing workflows and reducing trust in file paths.
Common defensive patterns include:
- Use direct process-execution APIs with separate argument arrays instead of shell command construction
- Treat uploaded filenames and paths as untrusted data
- Generate server-side filenames and resolve files against controlled directories
- Apply strict path validation, canonicalization, and allowlisting where appropriate
- Disable optional external identification behavior when it is not required
- Run image-processing workers with least privilege and restricted filesystem access
- Limit network, credential, and operating-system permissions available to the Ruby process
How teams detect issues like this
Organizations can identify similar command-injection risks through:
- Static analysis rules for shell execution APIs, including Ruby backticks and equivalent process calls
- Code review checks for user-controlled values reaching command strings
- Searches for image-processing paths, filenames, or upload metadata passed to shell interpreters
- Runtime monitoring of unexpected child processes spawned by image-processing workers
- Policy enforcement requiring argument-separated process execution and approved executable paths
Automated code review and software composition analysis tools may help identify unsafe command construction and affected dependency usage.
Organizations can identify similar command-injection risks through:
- Static analysis rules for shell execution APIs, including Ruby backticks and equivalent process calls
- Code review checks for user-controlled values reaching command strings
- Searches for image-processing paths, filenames, or upload metadata passed to shell interpreters
- Runtime monitoring of unexpected child processes spawned by image-processing workers
- Policy enforcement requiring argument-separated process execution and approved executable paths
Automated code review and software composition analysis tools may help identify unsafe command construction and affected dependency usage.
