Skip to content

Latest commit

 

History

History
151 lines (114 loc) · 16 KB

mitigations.md

File metadata and controls

151 lines (114 loc) · 16 KB

Mitigation Strategies Analysis for wasmerio/wasmer

Mitigation Strategy: Strict Module Source Validation

  • Description:

    1. Establish a Trusted Source List: Define a list of approved sources for WebAssembly modules (e.g., internal repositories, verified registries).
    2. Implement Checksum/Hash Verification:
      • Generate cryptographic hashes (e.g., SHA-256) of trusted WebAssembly modules.
      • Store these hashes securely alongside the module source information.
      • Before loading a module, calculate its hash and compare it against the stored trusted hash. Reject modules with mismatched hashes.
    3. Implement Code Signing (Optional but Recommended):
      • Set up a code signing infrastructure to digitally sign WebAssembly modules after they are built and verified.
      • Implement signature verification in the application before loading modules. Only load modules with valid signatures from trusted signers.
    4. Enforce Source Checks in Code: Integrate these validation steps directly into the application's code where WebAssembly modules are loaded.

  • Threats Mitigated:

    • Malicious Module Injection (Severity: High): Attackers injecting malicious WebAssembly modules to compromise the application or host system.
    • Module Tampering (Severity: High): Legitimate modules being altered after development to include malicious code.
    • Supply Chain Attacks (Severity: Medium): Compromised dependencies or build pipelines leading to the inclusion of malicious modules.

  • Impact:

    • Malicious Module Injection: Significantly Reduces - Effectively prevents loading of completely untrusted modules.
    • Module Tampering: Significantly Reduces - Detects modifications to legitimate modules through hash/signature verification.
    • Supply Chain Attacks: Moderately Reduces - Reduces risk if trusted sources are well-maintained and secured, but doesn't eliminate risks within trusted sources themselves.

  • Currently Implemented: Not Currently Implemented

  • Missing Implementation: This is missing in the module loading logic of the application. It needs to be implemented in the code that uses Wasmer to instantiate and run WebAssembly modules. Specifically, before wasmer::Instance::new() or similar instantiation functions, validation steps should be added.

Mitigation Strategy: Static Analysis of WebAssembly Modules

  • Description:

    1. Select Static Analysis Tools: Choose appropriate static analysis tools designed for WebAssembly (or general binary analysis tools adaptable to WASM). Examples include wasm-opt with optimization flags that can detect some issues, or more specialized security-focused tools if available.
    2. Integrate into CI/CD Pipeline: Incorporate static analysis tools into the Continuous Integration/Continuous Deployment pipeline. This ensures automated checks on every module build or update.
    3. Define Security Rule Sets: Configure the static analysis tools with relevant security rule sets. These rules should focus on common WebAssembly vulnerabilities like buffer overflows, integer overflows, and insecure import/export patterns. Consider creating custom rules tailored to the application's specific context.
    4. Automated Reporting and Blocking: Set up the CI/CD pipeline to automatically generate reports from static analysis. Configure the pipeline to fail builds or deployments if critical vulnerabilities are detected by the static analysis tools.
    5. Regular Rule Updates: Keep the static analysis tool rules and the tools themselves updated to address new vulnerabilities and improve detection accuracy.

  • Threats Mitigated:

    • Buffer Overflows in WASM Modules (Severity: High): Memory corruption vulnerabilities within WebAssembly modules that could lead to arbitrary code execution.
    • Integer Overflows/Underflows (Severity: Medium): Arithmetic vulnerabilities that can lead to unexpected behavior or security flaws.
    • Insecure Import/Export Usage (Severity: Medium): Vulnerabilities arising from improper handling of imported host functions or exported data, potentially leading to information leakage or privilege escalation.
    • Known Vulnerabilities in WASM Libraries (Severity: Medium): Detection of usage of vulnerable libraries or code patterns within the WebAssembly module.

  • Impact:

    • Buffer Overflows: Moderately Reduces - Static analysis can detect some, but not all, buffer overflow vulnerabilities. Dynamic testing is also needed.
    • Integer Overflows/Underflows: Moderately Reduces - Static analysis can identify potential integer overflow issues based on code patterns.
    • Insecure Import/Export Usage: Moderately Reduces - Can highlight suspicious import/export patterns but may require manual review for context.
    • Known Vulnerabilities in WASM Libraries: Moderately Reduces - Depends on the tool's vulnerability database and rule set coverage.

  • Currently Implemented: Partially Implemented - Basic linting might be in place, but dedicated WASM static security analysis is likely missing.

  • Missing Implementation: Integration of dedicated WebAssembly static analysis tools into the CI/CD pipeline. Configuration of security-focused rule sets and automated vulnerability reporting.

Mitigation Strategy: Robust Sandboxing and Isolation

  • Description:

    1. Configure Wasmer Engine Sandboxing: Review Wasmer's documentation on sandboxing features (e.g., using Config and Store to control resources). Ensure the Wasmer engine is initialized with sandboxing enabled and configured appropriately for the application's security needs.
    2. Implement Resource Limits:
      • Set memory limits for each WebAssembly instance to prevent memory exhaustion attacks. Use Wasmer's configuration options to restrict maximum memory usage.
      • Implement CPU time limits to prevent denial-of-service attacks by runaway WebAssembly code. Explore Wasmer's mechanisms for time limiting or external process monitoring.
      • Restrict file system access. By default, Wasmer provides limited file system access. Explicitly control and minimize any file system access granted to modules.
      • Disable or restrict network access unless absolutely necessary. If network access is required, implement strict controls and whitelisting of allowed destinations.
    3. Capability-Based Security Model:
      • Design the application architecture to follow the principle of least privilege.
      • Grant WebAssembly modules only the minimal necessary capabilities (imports, resources) required for their specific tasks. Avoid broad permissions.
      • Use Wasmer's import object mechanism to carefully control which host functions and data are exposed to each module.

  • Threats Mitigated:

    • Resource Exhaustion (DoS) (Severity: High): Malicious or buggy WebAssembly modules consuming excessive resources (CPU, memory) to cause denial of service.
    • File System Access Abuse (Severity: High): Unauthorized access to the host file system by WebAssembly modules, potentially leading to data theft or modification.
    • Network Access Abuse (Severity: High): Unauthorized network connections initiated by WebAssembly modules, potentially used for exfiltration or further attacks.
    • Sandbox Escape (Severity: Medium): Exploiting vulnerabilities in the Wasmer runtime or sandboxing implementation to break out of the sandbox and gain access to the host system.

  • Impact:

    • Resource Exhaustion (DoS): Significantly Reduces - Resource limits directly prevent modules from consuming excessive resources.
    • File System Access Abuse: Significantly Reduces - Restricting file system access limits the module's ability to interact with the host file system.
    • Network Access Abuse: Significantly Reduces - Restricting network access prevents unauthorized network activity.
    • Sandbox Escape: Moderately Reduces - Sandboxing adds a layer of defense, but sandbox escapes are still possible, especially in complex runtimes. Regular updates are crucial.

  • Currently Implemented: Partially Implemented - Basic sandboxing is likely enabled by default in Wasmer, but resource limits and capability-based security might not be explicitly configured and enforced.

  • Missing Implementation: Explicit configuration of Wasmer's sandboxing features, especially resource limits and a fine-grained capability-based security model for module imports. This needs to be implemented in the Wasmer engine initialization and module instantiation code.

Mitigation Strategy: Secure Import and Export Management

  • Description:

    1. Minimize Host Function Imports: Review all host functions imported into WebAssembly modules. Eliminate any imports that are not strictly necessary for the module's functionality. Reduce the attack surface by minimizing the number of exposed host functions.
    2. Input Validation for Host Functions:
      • For each host function imported into WebAssembly, implement rigorous input validation.
      • Validate all data passed from WebAssembly modules to host functions to ensure it conforms to expected types, formats, and ranges.
      • Sanitize inputs to prevent injection attacks (e.g., command injection, path traversal) if host functions interact with external systems or resources based on module inputs.
    3. Secure Export Handling:
      • Carefully examine data exported from WebAssembly modules to the host environment.
      • Sanitize and validate exported data before using it in the host application to prevent information leakage or unintended data exposure.
      • Ensure exported data does not contain sensitive information that should not be accessible to the host environment or other modules.

  • Threats Mitigated:

    • Injection Attacks via Host Functions (Severity: High): Attackers crafting malicious inputs to WebAssembly modules that are then passed to vulnerable host functions, leading to command injection, SQL injection, or other injection-based attacks on the host system.
    • Information Leakage via Exports (Severity: Medium): WebAssembly modules unintentionally or maliciously exporting sensitive data that should not be exposed to the host environment.
    • Privilege Escalation via Imports (Severity: Medium): Exploiting vulnerabilities in host functions to gain elevated privileges or bypass security controls on the host system.

  • Impact:

    • Injection Attacks via Host Functions: Significantly Reduces - Input validation on host functions directly mitigates injection vulnerabilities.
    • Information Leakage via Exports: Moderately Reduces - Sanitization and validation of exports reduces the risk of unintentional data exposure.
    • Privilege Escalation via Imports: Moderately Reduces - Secure import management and input validation make it harder to exploit host functions for privilege escalation.

  • Currently Implemented: Partially Implemented - Some basic input validation might be present in host functions, but likely not systematically and rigorously applied across all imports. Export handling might be less scrutinized.

  • Missing Implementation: Systematic and rigorous input validation for all host functions imported into WebAssembly modules. Formalized process for reviewing and securing data exports from modules. This needs to be implemented in the code defining and implementing host functions that are imported into Wasmer modules.

Mitigation Strategy: Regular Wasmer Updates

  • Description:

    1. Establish Update Monitoring: Subscribe to Wasmer's security advisories, release notes, and vulnerability announcements (e.g., through their GitHub repository, mailing lists, or security channels).
    2. Define Update Cadence: Establish a regular schedule for reviewing and applying Wasmer updates. This should be aligned with the project's overall security update policy.
    3. Test Updates in Staging: Before deploying updates to production, thoroughly test them in a staging or testing environment to ensure compatibility and stability with the application.
    4. Automate Update Process (If Possible): Explore automating the Wasmer update process within the project's dependency management and deployment pipelines to streamline updates and reduce manual effort.

  • Threats Mitigated:

    • Known Vulnerabilities in Wasmer Runtime (Severity: High): Exploiting publicly known vulnerabilities in older versions of the Wasmer runtime itself.
    • Dependency Vulnerabilities (Severity: Medium): Vulnerabilities in Wasmer's dependencies (libraries it relies on).

  • Impact:

    • Known Vulnerabilities in Wasmer Runtime: Significantly Reduces - Regular updates patch known vulnerabilities, directly reducing the risk of exploitation.
    • Dependency Vulnerabilities: Significantly Reduces - Updates often include updates to dependencies, addressing vulnerabilities in those components as well.

  • Currently Implemented: Partially Implemented - Dependency management practices likely exist, but a formal process for monitoring and proactively applying Wasmer security updates might be missing.

  • Missing Implementation: Formalized process for monitoring Wasmer security advisories and proactively scheduling and applying updates. Integration of Wasmer update checks into dependency management and CI/CD pipelines.

Mitigation Strategy: Runtime Configuration Hardening

  • Description:

    1. Review Wasmer Configuration Options: Thoroughly review Wasmer's configuration documentation and identify security-related settings. Pay attention to options related to sandboxing, resource limits, compilation settings, and feature flags.
    2. Disable Unnecessary Features: Disable any Wasmer features or functionalities that are not required by the application. This reduces the attack surface by removing potentially vulnerable or unnecessary code paths. For example, if specific compilation backends or experimental features are not needed, disable them.
    3. Enable Security Enhancements: Enable any Wasmer configuration options that enhance security, such as stricter sandboxing modes or security-focused compilation flags (if available and applicable).
    4. Document Configuration: Document all Wasmer runtime configuration settings, especially those related to security, to ensure consistent and auditable deployments.

  • Threats Mitigated:

    • Exploitable Features (Severity: Medium): Vulnerabilities in optional or less-used features of Wasmer that might be enabled by default but are not needed by the application.
    • Default Configuration Weaknesses (Severity: Low): Default Wasmer configurations might not be optimally secure for all environments. Hardening configuration improves baseline security.

  • Impact:

    • Exploitable Features: Moderately Reduces - Disabling unnecessary features removes potential attack vectors.
    • Default Configuration Weaknesses: Minimally Reduces - Hardening configuration provides incremental security improvements over default settings.

  • Currently Implemented: Partially Implemented - Basic configuration might be set up, but security-focused hardening of Wasmer runtime configuration is likely not explicitly performed.

  • Missing Implementation: Security review of Wasmer runtime configuration options and implementation of hardening measures. Documentation of the security-focused configuration. This needs to be done during the Wasmer engine initialization phase of the application.