Skip to content

Latest commit

 

History

History
57 lines (48 loc) · 6.28 KB

threat-modeling.md

File metadata and controls

57 lines (48 loc) · 6.28 KB

Threat Model Analysis for apache/commons-io

Threat: Threat: Arbitrary File Overwrite via Zip Slip

  • Threat: Arbitrary File Overwrite via Zip Slip
    • Description: An attacker crafts a malicious ZIP archive containing files with names that include directory traversal sequences (e.g., ../../foo.txt). The application uses Commons IO's FilenameUtils.normalize() to process the filenames but does not validate the resulting absolute path before writing the extracted files. The attacker aims to overwrite critical system files or configuration files outside the intended extraction directory.
    • Impact: System compromise, data corruption, denial of service, potential code execution (if overwritten files are executable or configuration files that control application behavior).
    • Affected Component: FilenameUtils.normalize() (when used incorrectly in conjunction with ZIP file extraction). The core issue is not normalize() itself, but its misuse in the context of file extraction without proper validation.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Primary: Always validate the absolute, final file path after any normalization and before creating any files during extraction. Ensure the resulting path is within the intended, sandboxed extraction directory. Do not rely solely on FilenameUtils.normalize().
      • Strongly Recommended: Use a dedicated ZIP library (e.g., Apache Commons Compress) that provides built-in protection against Zip Slip, rather than manually handling file paths with Commons IO.
      • Avoid extracting ZIP archives from untrusted sources.
      • Implement a strict whitelist of allowed characters in filenames.
      • Run the application with the least necessary privileges.

Threat: Threat: Denial of Service via Large File Upload/Copy

  • Threat: Denial of Service via Large File Upload/Copy
    • Description: An attacker uploads or provides a path to an extremely large file to an application endpoint that uses Commons IO to read or copy the file (e.g., FileUtils.copyFile(), FileUtils.readFileToString(), IOUtils.copy()). The attacker's goal is to exhaust server resources (memory, disk space, CPU) and make the application unresponsive.
    • Impact: Denial of service, application crash, potential system instability.
    • Affected Component: FileUtils.copyFile(), FileUtils.readFileToString(), FileUtils.readLines(), IOUtils.copy(), IOUtils.toByteArray(), and any other methods that read or write entire files or large chunks of data.
    • Risk Severity: High
    • Mitigation Strategies:
      • Implement strict input validation on file sizes. Reject files exceeding a predefined maximum size limit.
      • Use streaming operations (e.g., IOUtils.copy(InputStream, OutputStream)) with a reasonable buffer size (e.g., 4KB, 8KB) instead of loading entire files into memory.
      • Set resource limits (memory, disk space) on the application process.
      • Implement timeouts for file operations to prevent them from running indefinitely.
      • Monitor resource usage and alert on unusual activity.

Threat: Threat: Denial of Service via File Handle Exhaustion

  • Threat: Denial of Service via File Handle Exhaustion
    • Description: An attacker triggers a code path within the application that repeatedly opens files using Commons IO utilities (e.g., within a loop) but fails to close them properly. The attacker aims to exhaust the operating system's limit on open file handles, preventing the application (and potentially other processes) from opening new files.
    • Impact: Denial of service, application instability, potential system-wide impact.
    • Affected Component: Any Commons IO method that opens a file stream (e.g., FileUtils.openInputStream(), FileUtils.openOutputStream(), methods that use these internally like FileUtils.readFileToString()).
    • Risk Severity: High
    • Mitigation Strategies:
      • Crucial: Always close file streams (InputStreams, OutputStreams, Readers, Writers) in a finally block or using Java's try-with-resources statement to guarantee closure, even if exceptions occur.
      • Prefer Commons IO methods that automatically handle closing, such as FileUtils.readFileToString() (but be mindful of memory usage for large files).
      • Conduct code reviews to identify and fix potential resource leaks.
      • Use static analysis tools to detect unclosed resources.

Threat: Threat: Sensitive Data Exposure via Temporary File Mishandling

  • Threat: Sensitive Data Exposure via Temporary File Mishandling
    • Description: The application uses Commons IO to create temporary files (e.g., FileUtils.getTempDirectory(), File.createTempFile()) to store sensitive data. The attacker gains access to the temporary file directory (e.g., through a separate vulnerability or misconfiguration) and reads the contents of the temporary files before they are deleted (or if they are not deleted properly).
    • Impact: Exposure of sensitive data (passwords, API keys, PII), potential for further attacks.
    • Affected Component: FileUtils.getTempDirectory(), File.createTempFile() (and any methods that use them internally).
    • Risk Severity: High
    • Mitigation Strategies:
      • Crucial: Always delete temporary files explicitly using FileUtils.deleteQuietly() or File.delete() (with error handling) in a finally block or using try-with-resources.
      • Set restrictive file permissions on temporary files when creating them, limiting access to the application's user.
      • If possible, use in-memory operations (e.g., ByteArrayOutputStream) instead of temporary files to avoid filesystem persistence.
      • Regularly audit and clean up temporary file directories.
      • Consider using a dedicated temporary file management library that provides stronger security guarantees.