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44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
# TaintedFile
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This rule is emitted when user-controlled input can be passed into a sensitive file operation.
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## Risk
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The risk here depends on the actual operation that contains user-controlled input, and how it is later on processed.
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It could range from:
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- Creating files
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- Example: `file_put_contents`
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- Risk: Depending on the server configuration this may result in remote code execution. (e.g. writing a file in the web root)
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- Modifying files
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- Example: `file_put_contents`
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- Risk: Depending on the server configuration this may result in remote code execution. (e.g. modifying a PHP file)
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- Reading files
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- Example: `file_get_contents`
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- Risk: Sensitive data could be exposed from the filesystem. (e.g. config values, source code, user-submitted files)
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- Deleting files
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- Example: `unlink`
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- Risk: Denial of Service or potentially RCE. (e.g. deleting application code, removing a .htaccess file)
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## Example
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```php
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<?php
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$content = file_get_contents($_GET['header']);
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echo $content;
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```
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## Mitigations
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Use an allowlist approach where possible to verify names on file operations.
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Sanitize user-controlled filenames by stripping `..`, `\` and `/`.
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## Further resources
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- [File Upload Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/File_Upload_Cheat_Sheet.html)
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- [OWASP Wiki for Unrestricted FIle Upload](https://owasp.org/www-community/vulnerabilities/Unrestricted_File_Upload)
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- [CWE-73](https://cwe.mitre.org/data/definitions/73.html)
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