Skip to content

Latest commit

 

History

History
125 lines (94 loc) · 10.2 KB

mitigations.md

File metadata and controls

125 lines (94 loc) · 10.2 KB

Mitigation Strategies Analysis for pistondevelopers/piston

Mitigation Strategy: Language and Runtime Restrictions (Piston Configuration and Usage)

  • Description:

    1. Language Selection (Piston's Supported Languages): Within the set of languages supported by Piston, choose those with the strongest security features. Prioritize Rust, Go (with extremely careful review of any unsafe code), or WebAssembly. If using interpreted languages (Python, Node.js), strictly adhere to step 2.
    2. Module Whitelisting (Interpreted Languages - Within Piston's Execution Context):
      • Create a very restrictive whitelist of allowed modules. This list should only contain modules that are absolutely essential for the intended functionality. Never include modules that provide system access (e.g., os, subprocess, child_process, fs, ctypes, ffi).
      • Crucially, this whitelisting must be enforced within the Piston execution environment. This might involve:
        • Modifying the Piston source code (if necessary and carefully reviewed) to add custom module import restrictions. This is the most robust, but also most complex, approach.
        • Using language-specific features within the executed code to limit module imports (e.g., overriding the __import__ function in Python – but this is easily bypassed if the attacker has full code control). This is less reliable.
        • Using Piston's "pre-execution" hooks (if available) to inject code that restricts module imports before the user-provided code runs. This is a good compromise if Piston supports it.
    3. Runtime Updates (Piston's Dependencies): Keep the language runtimes used by Piston up-to-date. This is distinct from updating Piston itself. This often involves managing the Docker image or environment that Piston uses. Automate this process as much as possible.

  • Threats Mitigated:

    • Remote Code Execution (RCE) (Critical): Malicious code injection leading to arbitrary command execution. Module whitelisting and language selection are the primary defenses here.
    • Denial of Service (DoS) (High): Some DoS attacks can be mitigated by language choice (e.g., memory-safe languages).
    • Information Disclosure (Medium): Limiting access to system modules reduces the risk of leaking sensitive information.
    • Privilege Escalation (High): Restricting language features and modules makes it harder for an attacker to gain more privileges.

  • Impact:

    • RCE: Risk significantly reduced by the combination of language choice and strict, Piston-enforced module whitelisting.
    • DoS: Risk moderately reduced (primarily through language choice).
    • Information Disclosure: Risk moderately reduced.
    • Privilege Escalation: Risk moderately reduced.

  • Currently Implemented:

    • Language Selection: [Specify the currently used languages, focusing on those supported by Piston and their security implications.]
    • Module Whitelisting: [Specify if Piston-enforced module whitelisting is implemented and how. Be very specific about how this is enforced within Piston's execution context.]
    • Runtime Updates: [Specify if updates to the language runtimes used by Piston are automated.]

  • Missing Implementation:

    • Language Selection: [Identify any languages that need review or replacement within Piston's supported set. ]
    • Module Whitelisting: [Specify any gaps in Piston-enforced module whitelisting. This is the most critical area.]
    • Runtime Updates: [Specify any manual update processes or runtimes used by Piston that are not automatically updated.]

Mitigation Strategy: Resource Limits (Piston Configuration)

  • Description:

    1. Baseline Measurement: Run test executions of representative code snippets to determine typical resource usage (memory, CPU time, process creation, file I/O).
    2. Configure Piston's runtime Settings: Use Piston's configuration mechanism (e.g., a piston.toml file, environment variables, or API calls – depending on how Piston is integrated) to set strict limits:
      • memory_limit: Set a maximum memory allocation (e.g., "64MB"). This is crucial.
      • cpu_time_limit: Set a maximum execution time (e.g., "1s"). This is also crucial.
      • process_limit: Set a maximum number of processes (e.g., "1"). Essential to prevent fork bombs.
      • file_size_limit: Set a maximum file size for created files (e.g., "1MB"). Important to prevent disk exhaustion.
    3. Testing and Iteration: Thoroughly test with a variety of inputs to ensure the limits are appropriate and don't break legitimate functionality. Adjust as needed.
    4. Network Restrictions: Ensure that network access is disabled within Piston's configuration. This is usually the default, but verify it. If network access is absolutely required, it should be handled completely outside of Piston, with Piston communicating with a separate, secured service via a very restricted API.

  • Threats Mitigated:

    • Denial of Service (DoS) (High): Prevents resource exhaustion attacks (memory, CPU, disk space, processes).
    • Resource Abuse (Medium): Limits the ability of malicious code to consume excessive resources.

  • Impact:

    • DoS: Risk significantly reduced. Strict resource limits are highly effective.
    • Resource Abuse: Risk significantly reduced.

  • Currently Implemented:

    • [Specify exactly which resource limits are configured in Piston and their values (e.g., "Memory limit set to 128MB via the PISTON_MEMORY_LIMIT environment variable").]

  • Missing Implementation:

    • [Specify any missing resource limits or limits that need adjustment within Piston's configuration. ]
    • [Explicitly state whether network access is disabled in Piston's configuration.]

Mitigation Strategy: Input Handling (Within Piston's Control)

  • Description:

    1. Length Limits (Enforced by Piston): If Piston provides a mechanism to limit the size of the input code before it's passed to the language runtime, use it. This might be a configuration setting or an API parameter. This is distinct from length limits enforced by the application using Piston.
    2. Reject Invalid Code (Pre-Execution Checks within Piston): If Piston offers any pre-execution checks (e.g., basic syntax validation using language-specific tools integrated into Piston), enable them. This prevents Piston from even attempting to run malformed code that might exploit vulnerabilities in the language runtimes.

  • Threats Mitigated:

    • Denial of Service (DoS) (Medium): Length limits (if enforced by Piston) can prevent some DoS attacks.
    • Exploits Targeting Runtime Vulnerabilities (Variable): Pre-execution checks (if available in Piston) can prevent execution of code designed to exploit specific vulnerabilities.

  • Impact:

    • DoS: Risk moderately reduced by Piston-enforced length limits.
    • Exploits: Risk reduction depends on the specific pre-execution checks available in Piston.

  • Currently Implemented:

    • Length Limits: [Specify if Piston has a built-in mechanism for limiting input size and if it's used.]
    • Pre-Execution Checks: [Specify if Piston has any built-in pre-execution validation and if it's enabled.]

  • Missing Implementation:

    • [Specify any missing input handling features within Piston's capabilities.]

Mitigation Strategy: Output Handling (Within Piston's Control)

  • Description:

    1. Output Length Limits (Enforced by Piston): If Piston provides a mechanism to limit the size of the output generated by the executed code, use it. This is a configuration setting or API parameter within Piston.
    2. Error Handling (Piston's Error Reporting): If Piston allows customizing how errors are reported, ensure that detailed error messages and stack traces from the executed code are not exposed. Return only generic error messages. This might involve configuring Piston or modifying its error handling logic.

  • Threats Mitigated:

    • Denial of Service (DoS) (Low): Output length limits prevent excessively large outputs.
    • Information Disclosure (Medium): Generic error messages prevent leaking sensitive information.

  • Impact:

    • DoS: Risk slightly reduced by Piston-enforced output length limits.
    • Information Disclosure: Risk significantly reduced by controlling Piston's error reporting.

  • Currently Implemented:

    • Output Length Limits: [Specify if Piston has a built-in mechanism for limiting output size and if it's used.]
    • Error Handling: [Specify how Piston's error reporting is configured and whether detailed error information is suppressed.]

  • Missing Implementation:

    • [Specify any missing output handling features within Piston's capabilities.]

Mitigation Strategy: Regular Updates (Piston Library Itself)

  • Description:

    1. Establish a process for monitoring new releases of the Piston library itself (e.g., subscribe to release notifications on GitHub).
    2. When a new release is available, review the changelog for security-related fixes.
    3. Update the Piston library in your project's dependencies.
    4. Thoroughly test the application after updating Piston.

  • Threats Mitigated:

    • Vulnerabilities in Piston (Variable Severity): Addresses security vulnerabilities discovered and fixed in the Piston library.

  • Impact:

    • Vulnerabilities in Piston: Risk reduced depending on the severity of the patched vulnerabilities.

  • Currently Implemented:

    • [Specify the process for updating the Piston library.]

  • Missing Implementation:

    • [Specify any improvements needed in the Piston library update process.]