threat-modeling.md

Threat Model Analysis for filebrowser/filebrowser

Threat: Unauthorized File Access (Scope Misconfiguration)

• Threat: Unauthorized File Access (Scope Misconfiguration)

  • Description: An attacker, either authenticated or unauthenticated (if anonymous access is enabled), can access files and directories outside the intended scope. This is achieved by manipulating URL paths or exploiting weaknesses in how File Browser handles path traversal. The attacker might try common directory traversal patterns (e.g., ../) or guess file/directory names. This is a direct vulnerability in how File Browser processes and validates file paths.
  • Impact: Data breach; unauthorized disclosure of sensitive information; potential for data modification or deletion if write access is also misconfigured.
  • Affected Component: filebrowser/filebrowser core file handling logic, specifically the scope and rules processing within the server's request handling (likely in functions related to path validation and authorization checks). This is internal to File Browser's code.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict Scope Definition: Define the scope in filebrowser.json to be as restrictive as possible, pointing to the absolute minimum necessary directory.
    • Granular Rules: Use rules to define fine-grained access control for specific users and groups, limiting access to specific subdirectories and file types.
    • Path Traversal Prevention: Ensure robust path traversal prevention is implemented within File Browser's code. This should involve canonicalizing paths (resolving . and ..) before checking permissions. The Go standard library's filepath.Clean() function is a good starting point, but additional checks may be needed within File Browser.
    • Regular Expression Validation (Careful Use): If using regular expressions in rules, ensure they are extremely carefully crafted to avoid unintended matches. Prefer simpler, more restrictive matching where possible.
    • Testing: Rigorous testing with various URL manipulations and user roles. This testing should specifically target File Browser's path handling.

Threat: Unauthorized File Upload (Upload Misconfiguration)

• Threat: Unauthorized File Upload (Upload Misconfiguration)

  • Description: An attacker uploads malicious files (e.g., web shells, malware) to the server. This is possible if the upload feature is enabled and either allows uploads to unrestricted locations, doesn't validate file types, or has insufficient file size limits. The attacker might use the web interface or craft custom HTTP requests to bypass client-side restrictions. This is a direct vulnerability in File Browser's upload handling.
  • Impact: Server compromise; execution of arbitrary code; malware distribution.
  • Affected Component: filebrowser/filebrowser upload handling logic (likely within functions related to the /api/resources endpoint and file writing operations). The commands feature, if enabled and misconfigured, could also be used to facilitate uploads. This is internal to File Browser.
  • Risk Severity: High
  • Mitigation Strategies:
    • Disable Uploads (If Possible): The most secure option if uploads are not required.
    • Restricted Upload Directories: Limit uploads to specific, non-executable directories. Avoid allowing uploads to webroot or directories containing executable code.
    • Strict File Type Whitelisting: Use a whitelist of allowed file extensions (and MIME types, if possible). Do not use a blacklist. Validate the file type after upload, not just based on the filename. This validation must be done within File Browser.
    • File Size Limits: Enforce strict file size limits within File Browser's configuration.
    • Virus Scanning: Integrate with a virus scanning solution (e.g., ClamAV) to scan uploaded files before they are written to disk. This requires integration with File Browser.
    • Rename Uploaded Files: Rename uploaded files to randomly generated names to prevent attackers from predicting filenames and accessing them directly. This renaming should be handled by File Browser.

Threat: Unauthorized File Modification/Deletion (Write Access Misconfiguration)

• Threat: Unauthorized File Modification/Deletion (Write Access Misconfiguration)

  • Description: An attacker with write access (either legitimately or through a misconfiguration) modifies or deletes files they should not be able to. This could be due to overly permissive rules or a vulnerability in the authorization checks within File Browser.
  • Impact: Data loss; data corruption; system instability; potential for privilege escalation if system files are modified.
  • Affected Component: filebrowser/filebrowser file modification and deletion logic (likely within functions related to the /api/resources endpoint and file system operations). This is internal to File Browser.
  • Risk Severity: High
  • Mitigation Strategies:
    • Principle of Least Privilege: Grant write access only to users and directories where it is absolutely necessary.
    • Read-Only Mode: Use read-only mode for users who only need to view files.
    • Regular Audits: Regularly review the filebrowser.json configuration to ensure permissions are correct.
    • Input Validation: Ensure that user-supplied input (e.g., file paths) is properly validated within File Browser before being used in file system operations.

Threat: Command Execution (Exploiting commands Feature)

• Threat: Command Execution (Exploiting commands Feature)

  • Description: An attacker exploits the commands feature to execute arbitrary shell commands on the server. This is possible if the feature is enabled and either allows unrestricted commands or has vulnerabilities in how user input is handled within File Browser. The attacker might inject malicious commands through the web interface or by crafting custom requests.
  • Impact: Complete server compromise; remote code execution; data exfiltration; system destruction.
  • Affected Component: filebrowser/filebrowser command execution logic (specifically the functions related to processing and executing commands defined in filebrowser.json). This is entirely internal to File Browser.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Disable Commands (Strongly Recommended): Disable the commands feature entirely if it is not essential. This is the best mitigation.
    • Strict Command Whitelisting: If commands are required, define a very limited whitelist of allowed commands. Do not allow arbitrary commands or user-supplied commands.
    • Parameter Sanitization (Extremely Difficult): If user input must be used as parameters to commands, implement extremely rigorous input validation and sanitization within File Browser's code. This is very prone to errors and should be avoided if at all possible. Consider using a dedicated library for command construction and escaping.
    • Least Privilege (Operating System): Run the File Browser process with the lowest possible operating system privileges. Do not run it as root. Use a dedicated, unprivileged user account. (While this is an OS-level mitigation, it's crucial in the context of this specific, high-risk File Browser feature).

Threat: Brute-Force Authentication

• Threat: Brute-Force Authentication
  • Description: An attacker attempts to guess user passwords by repeatedly trying different combinations.
  • Impact: Unauthorized access to user accounts; potential for data breach or other malicious actions.
  • Affected Component: filebrowser/filebrowser authentication logic (likely within functions related to user login and password verification).
  • Risk Severity: High
  • Mitigation Strategies:
    • Strong Password Policies: Enforce strong password policies, requiring a minimum length and complexity.
    • Account Lockout: Implement account lockout after a specified number of failed login attempts.
    • Rate Limiting (Authentication Attempts): Implement rate limiting specifically for authentication attempts to slow down brute-force attacks.

Threat: Outdated Software

• Threat: Outdated Software

  • Description: Running an outdated version of File Browser with known vulnerabilities that an attacker can exploit.
  • Impact: Varies depending on the vulnerability; could range from information disclosure to remote code execution.
  • Affected Component: Potentially any component, depending on the specific vulnerability.
  • Risk Severity: High (depending on the vulnerability)
  • Mitigation Strategies:
    • Regular Updates: Keep File Browser updated to the latest version.
    • Vulnerability Scanning: Regularly scan the application and its dependencies for known vulnerabilities.
    • Automated Updates (If Feasible): Consider automating the update process, if appropriate for your environment.