Summary
ApiAdmin v5.0 and earlier accept uploaded files without restricting extensions, validating content, or enforcing an upload policy. An authenticated administrator may upload server-side executable content into a web-accessible directory, which could allow remote code execution when the file is subsequently requested.
ApiAdmin v5.0 and earlier accept uploaded files without restricting extensions, validating content, or enforcing an upload policy. An authenticated administrator may upload server-side executable content into a web-accessible directory, which could allow remote code execution when the file is subsequently requested.
Affected context
The issue occurs in the administrative file-upload functionality when uploaded content is placed under a web-accessible path and the original file extension is preserved. Risk is elevated where authenticated administrative accounts can use the upload endpoint and the web server is configured to interpret uploaded files as executable code.
The issue occurs in the administrative file-upload functionality when uploaded content is placed under a web-accessible path and the original file extension is preserved. Risk is elevated where authenticated administrative accounts can use the upload endpoint and the web server is configured to interpret uploaded files as executable code.
Exploit preconditions
- Attack surface: Administrative HTTP file-upload endpoint
- Required access: An authenticated account with permission to use the upload function
- Trigger point: Processing and storage of an uploaded file
- Why exploitation is possible: File types and content are not sufficiently restricted, while uploaded files are stored in a directory reachable through the web server
- Attack surface: Administrative HTTP file-upload endpoint
- Required access: An authenticated account with permission to use the upload function
- Trigger point: Processing and storage of an uploaded file
- Why exploitation is possible: File types and content are not sufficiently restricted, while uploaded files are stored in a directory reachable through the web server
Why this happens
The underlying flaw is an unrestricted file-upload design combined with unsafe placement of user-controlled files. The application accepts the supplied extension without an allowlist, denylist, or meaningful content validation, then stores the file in a web-accessible directory. This behavior is associated with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, because attacker-controlled file placement is not adequately constrained to a safe, non-executable storage context.
The underlying flaw is an unrestricted file-upload design combined with unsafe placement of user-controlled files. The application accepts the supplied extension without an allowlist, denylist, or meaningful content validation, then stores the file in a web-accessible directory. This behavior is associated with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, because attacker-controlled file placement is not adequately constrained to a safe, non-executable storage context.
Potential impact
- An attacker may execute server-side code with the privileges of the web application
- The application or underlying host could be compromised
- Sensitive files and application data may be accessed or modified
- The server could be used for lateral movement or further attacks
- Uploaded content could be used to persist unauthorized access
- An attacker may execute server-side code with the privileges of the web application
- The application or underlying host could be compromised
- Sensitive files and application data may be accessed or modified
- The server could be used for lateral movement or further attacks
- Uploaded content could be used to persist unauthorized access
General mitigation guidance
Mitigation generally focuses on reducing trust in uploaded filenames and isolating uploaded content from executable application paths.
Common defensive patterns include:
- Allowing only narrowly defined, business-required file types based on verified content
- Generating server-side filenames rather than preserving user-controlled names or extensions
- Storing uploads outside the web root or in storage that cannot execute server-side code
- Applying explicit web-server rules that disable script execution in upload locations
- Validating file size, structure, encoding, and media type consistently
- Restricting upload functionality through least-privilege roles and narrowly scoped permissions
- Preventing path components and traversal sequences from influencing storage destinations
- Logging upload activity and reviewing administrative file changes
Mitigation generally focuses on reducing trust in uploaded filenames and isolating uploaded content from executable application paths.
Common defensive patterns include:
- Allowing only narrowly defined, business-required file types based on verified content
- Generating server-side filenames rather than preserving user-controlled names or extensions
- Storing uploads outside the web root or in storage that cannot execute server-side code
- Applying explicit web-server rules that disable script execution in upload locations
- Validating file size, structure, encoding, and media type consistently
- Restricting upload functionality through least-privilege roles and narrowly scoped permissions
- Preventing path components and traversal sequences from influencing storage destinations
- Logging upload activity and reviewing administrative file changes
How teams detect issues like this
Detection approaches can include:
- Static analysis rules for file-upload handlers that preserve user-controlled names or extensions
- Code review checks for web-accessible upload directories and missing content validation
- Policy enforcement requiring uploads to use non-executable storage and generated object identifiers
- Runtime monitoring for unexpected executable files, unusual upload activity, and requests targeting newly created files
- Web-server and application logs correlating administrative uploads with subsequent file requests
- Automated security review tools that identify unrestricted upload and unsafe path-handling patterns
Detection approaches can include:
- Static analysis rules for file-upload handlers that preserve user-controlled names or extensions
- Code review checks for web-accessible upload directories and missing content validation
- Policy enforcement requiring uploads to use non-executable storage and generated object identifiers
- Runtime monitoring for unexpected executable files, unusual upload activity, and requests targeting newly created files
- Web-server and application logs correlating administrative uploads with subsequent file requests
- Automated security review tools that identify unrestricted upload and unsafe path-handling patterns
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
