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attack-surface.md

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Attack Surface Analysis for apache/commons-io

Attack Surface: Path Traversal Vulnerability

  • Description: Attackers can manipulate file paths provided as input to bypass intended directory restrictions and access files or directories outside the allowed scope. This is possible when applications use Commons IO functions to operate on file paths derived from user input without proper sanitization.
  • How Commons-IO contributes to the attack surface: Commons IO functions like FileUtils.readFileToString, FileUtils.copyFile, FilenameUtils.normalize, and others handle file paths. If an application directly uses user-controlled strings as input to these functions without validation, it becomes susceptible to path traversal attacks.
  • Example: An application uses FileUtils.readFileToString(userInputPath) to display file content. If userInputPath is directly taken from user input and an attacker provides ../../../../etc/passwd, Commons IO will attempt to read this path. If the application lacks path validation before calling FileUtils.readFileToString, the attacker can potentially read the sensitive /etc/passwd file.
  • Impact:
    • Unauthorized access to sensitive files (configuration files, application data, system files).
    • Information disclosure of confidential data.
    • Potential for further exploitation, including arbitrary code execution in certain scenarios if combined with other vulnerabilities.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict Input Validation: Thoroughly validate all user-provided file paths before using them with Commons IO functions. Implement whitelisting of allowed characters and patterns. Reject paths containing path traversal sequences like ../ or absolute paths.
    • Secure Path Normalization: Use FilenameUtils.normalize with caution and understanding of its limitations. It should be used as part of a broader validation strategy, not as the sole defense.
    • Principle of Least Privilege: Run the application with minimal file system permissions. Restrict the application's access to only the necessary directories and files, limiting the impact of potential path traversal exploits.

Attack Surface: Denial of Service (DoS) through File Operations

  • Description: Attackers can exploit Commons IO's file operation functionalities to initiate resource-intensive operations on large files or directories, leading to excessive consumption of server resources and causing application slowdown or failure.
  • How Commons-IO contributes to the attack surface: Commons IO provides functions like FileUtils.copyDirectory, FileUtils.deleteDirectory, FileUtils.sizeOfDirectory, and similar functions that can be resource-intensive when dealing with large file systems. If an application allows user-controlled operations using these functions without proper resource management, it can be exploited for DoS.
  • Example: An application allows users to trigger directory copying using FileUtils.copyDirectory(userInputDirPath, outputPath). If an attacker provides userInputDirPath pointing to an extremely large directory or initiates multiple copy requests for large directories, Commons IO will execute these operations. Without resource limits, this can overwhelm the server's CPU, memory, and disk I/O, leading to a DoS.
  • Impact:
    • Application unresponsiveness or slowdown.
    • Application crash due to resource exhaustion.
    • Service disruption for legitimate users.
  • Risk Severity: High
  • Mitigation Strategies:
    • Implement Resource Limits: Enforce limits on file sizes, directory depths, and the number of files processed in a single operation when using Commons IO file functions.
    • Set Timeouts: Configure timeouts for file operations to prevent indefinite blocking and resource exhaustion if operations take too long.
    • Rate Limiting: Limit the frequency of file-related operations initiated by a single user or source to prevent abuse and DoS attacks.
    • Asynchronous Processing: For potentially long-running file operations, consider using asynchronous processing to avoid blocking the main application thread and maintain responsiveness.

Attack Surface: Information Disclosure through File Reading

  • Description: Attackers can potentially bypass authorization checks and read the content of sensitive files that the application has access to by exploiting vulnerabilities in how file reading functions from Commons IO are used in conjunction with insufficient authorization logic.
  • How Commons-IO contributes to the attack surface: Commons IO functions like FileUtils.readFileToString, FileUtils.readLines, and others are designed to read file content. If an application uses these functions to read files based on user-controlled paths without performing adequate authorization checks beforehand, it creates a risk of information disclosure.
  • Example: An application intends to allow users to read specific log files, but due to a flaw in authorization logic before using FileUtils.readFileToString(userInputLogFilePath), an attacker can manipulate userInputLogFilePath to point to a different, more sensitive file (e.g., a configuration file) that the application process has access to. Commons IO will then read and potentially expose the content of this unauthorized file.
  • Impact:
    • Disclosure of sensitive application data, configuration details, internal logs, or other confidential information.
    • Potential compromise of application security and further attacks based on the revealed information.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Robust Authorization Checks: Implement strong authorization mechanisms before using Commons IO file reading functions. Verify if the user is explicitly authorized to access the requested file based on their roles, permissions, and the intended application logic.
    • Principle of Least Privilege: Minimize the application's file system permissions to reduce the scope of potential information disclosure. Grant access only to the files and directories that are absolutely necessary for the application's functionality.
    • Secure Configuration Management: Store sensitive configuration data securely (e.g., encrypted, outside the web root) and restrict access even for the application itself to only when strictly required.