Skip to content

Latest commit

 

History

History
82 lines (57 loc) · 10.8 KB

mitigations.md

File metadata and controls

82 lines (57 loc) · 10.8 KB

Mitigation Strategies Analysis for facebook/hermes

Mitigation Strategy: Keep Hermes Updated

  • Description:

    1. Monitor Hermes Releases: Regularly check the official Hermes GitHub repository (https://github.com/facebook/hermes/releases) for new Hermes versions and security advisories.
    2. Update Hermes Dependency: Update the specific dependency in your project that includes Hermes. For React Native projects, this often means updating the react-native version, as Hermes is integrated within it. Ensure you are updating to a stable version that includes the latest Hermes release.
    3. Test Hermes Integration: After updating, specifically test the JavaScript functionality powered by Hermes in your application to confirm compatibility and identify any issues introduced by the Hermes update. Focus on performance and core JavaScript execution paths.

  • List of Threats Mitigated:

    • Exploitation of Known Hermes Vulnerabilities (High Severity): Outdated Hermes versions may contain known security flaws that can be directly exploited by attackers targeting the JavaScript engine. Updating patches these specific Hermes vulnerabilities.
    • Denial of Service due to Hermes Bugs (Medium Severity): Bugs within Hermes itself, present in older versions, could be exploited to cause crashes or performance degradation specifically within the JavaScript execution environment, leading to denial of service.

  • Impact:

    • Exploitation of Known Hermes Vulnerabilities (High Impact): Directly reduces the risk of exploits targeting known weaknesses in the Hermes engine itself.
    • Denial of Service due to Hermes Bugs (Medium Impact): Reduces the likelihood of DoS attacks that leverage bugs within Hermes' JavaScript execution.

  • Currently Implemented: Partially implemented in projects using frameworks like React Native, as framework updates often include Hermes version updates. However, consistent and timely updates focused specifically on Hermes security patches might be missing.

  • Missing Implementation: A proactive process for monitoring Hermes releases independently of framework updates, and a streamlined mechanism to update the Hermes version in the project specifically for security reasons, even if the overall framework version remains the same.

Mitigation Strategy: Secure Bytecode Integrity Verification

  • Description:

    1. Secure Hermes Bytecode Generation: Ensure that the process of precompiling JavaScript to Hermes bytecode is performed in a secure and trusted environment. This prevents malicious modification during the bytecode generation phase.
    2. Generate Bytecode Checksum: After generating Hermes bytecode, create a cryptographic checksum (e.g., SHA-256 hash) of the bytecode file. This checksum acts as a fingerprint of the legitimate bytecode.
    3. Securely Store Bytecode Checksum: Store this checksum in a secure location, ideally within the application package or secure configuration, separate from the bytecode itself. This prevents attackers from easily modifying both the bytecode and its checksum.
    4. Hermes Bytecode Verification at Runtime: Before Hermes loads and executes bytecode, recalculate the checksum of the bytecode file at runtime using the same algorithm.
    5. Compare Runtime Checksum with Stored Checksum: Compare the runtime-generated checksum with the securely stored checksum. If the checksums do not match, it indicates potential tampering. In this case, prevent Hermes from loading the bytecode and handle the error appropriately (e.g., terminate the application or load fallback JavaScript).

  • List of Threats Mitigated:

    • Malicious Hermes Bytecode Injection (High Severity): Prevents attackers from replacing legitimate Hermes bytecode with malicious bytecode. By verifying integrity, you ensure Hermes only executes bytecode that has not been tampered with.
    • Hermes Bytecode Corruption (Medium Severity): Protects against accidental or intentional corruption of Hermes bytecode files during storage or distribution, which could lead to unexpected behavior or vulnerabilities in Hermes execution.

  • Impact:

    • Malicious Hermes Bytecode Injection (High Impact): Significantly reduces the risk of malicious code execution via bytecode injection specifically targeting the Hermes engine.
    • Hermes Bytecode Corruption (Medium Impact): Prevents issues arising from corrupted bytecode loaded by Hermes.

  • Currently Implemented: Generally not implemented by default. Developers need to explicitly add bytecode integrity verification steps to their build and application loading processes when using Hermes bytecode precompilation.

  • Missing Implementation: Implementation of bytecode checksum generation, secure storage, and runtime verification specifically for Hermes bytecode within the application's build pipeline and Hermes initialization logic. This requires custom development focused on Hermes bytecode handling.

Mitigation Strategy: Resource Limits for Hermes JavaScript Execution

  • Description:

    1. Configure Hermes Execution Timeouts: Utilize any available mechanisms within the application environment to set timeouts for JavaScript execution within Hermes. This limits the execution time of any single JavaScript task running in Hermes.
    2. Limit Hermes Memory Usage (if possible): Explore if the embedding environment provides ways to restrict the memory that the Hermes engine can allocate. If so, configure appropriate memory limits for Hermes to prevent excessive memory consumption by JavaScript code running in Hermes.
    3. Monitor Hermes Resource Consumption: Implement monitoring to track CPU and memory usage specifically by the Hermes engine. This allows for detection of unusual resource consumption patterns that might indicate a DoS attempt targeting Hermes' JavaScript execution.

  • List of Threats Mitigated:

    • Hermes JavaScript Denial of Service (DoS) - CPU Exhaustion (High Severity): Prevents malicious or inefficient JavaScript code running in Hermes from consuming excessive CPU resources, specifically impacting the performance and responsiveness of the Hermes JavaScript engine and the application.
    • Hermes JavaScript Denial of Service (DoS) - Memory Exhaustion (High Severity): Prevents malicious or memory-leaking JavaScript code executed by Hermes from consuming excessive memory, potentially leading to crashes or instability specifically within the Hermes runtime environment.

  • Impact:

    • Hermes JavaScript Denial of Service (DoS) - CPU Exhaustion (High Impact): Significantly reduces the impact of CPU-based DoS attacks specifically targeting JavaScript execution within Hermes.
    • Hermes JavaScript Denial of Service (DoS) - Memory Exhaustion (High Impact): Significantly reduces the impact of memory-based DoS attacks aimed at the Hermes JavaScript engine.

  • Currently Implemented: Often not explicitly configured for Hermes. General application resource management might exist, but specific timeouts and memory limits tailored to Hermes' JavaScript execution are usually not in place by default.

  • Missing Implementation: Explicit configuration of JavaScript execution timeouts specifically for Hermes. Implementation of memory limits applicable to the Hermes engine (if supported by the environment). Dedicated monitoring of Hermes' resource usage to detect and respond to potential DoS attacks targeting the JavaScript engine.

Mitigation Strategy: Hermes-Specific Security Testing

  • Description:

    1. Hermes Fuzzing: Employ fuzzing tools specifically designed or adapted to test JavaScript engines like Hermes. Feed a wide range of malformed, unexpected, and potentially malicious JavaScript inputs directly to Hermes to uncover crashes, memory corruption, or other vulnerabilities within the engine itself.
    2. Hermes Bytecode Analysis for Security: Conduct security-focused analysis of Hermes bytecode. This involves examining the compiled bytecode for potential vulnerabilities, unexpected code patterns, or security weaknesses introduced during the Hermes compilation process.
    3. Security Integration Tests Targeting Hermes: Design integration tests that specifically focus on the security aspects of how Hermes interacts with the application. These tests should target potential vulnerabilities in Hermes' JavaScript execution environment and its interaction with other application components.
    4. Hermes Vulnerability Scanning: Incorporate vulnerability scanning tools that can identify known vulnerabilities specifically within the Hermes engine or its dependencies. Regularly scan the Hermes version used in the project against known vulnerability databases.
    5. Penetration Testing Focused on Hermes: During penetration testing activities, explicitly include attack vectors that target the Hermes JavaScript engine. This could involve attempts to exploit JavaScript vulnerabilities within Hermes, manipulate bytecode loaded by Hermes, or identify weaknesses in Hermes' security features.

  • List of Threats Mitigated:

    • Undiscovered Hermes Vulnerabilities (High Severity): Proactively identifies and mitigates previously unknown security vulnerabilities that are specific to the Hermes JavaScript engine before they can be exploited in real-world attacks.
    • Security Issues in Hermes' Implementation (Medium Severity): Uncovers security-relevant bugs or weaknesses in the way Hermes is implemented, which might not be traditional "vulnerabilities" but could still lead to security problems in specific scenarios.

  • Impact:

    • Undiscovered Hermes Vulnerabilities (High Impact): Significantly reduces the risk of zero-day exploits that directly target the Hermes engine itself.
    • Security Issues in Hermes' Implementation (Medium Impact): Reduces the risk of security problems stemming from implementation-level issues within Hermes.

  • Currently Implemented: Very rarely implemented in typical application development workflows. Security testing often overlooks the specific JavaScript engine and focuses on higher-level application logic.

  • Missing Implementation: Integration of Hermes-specific fuzzing, bytecode security analysis, and security-focused integration testing into the software development lifecycle. Inclusion of Hermes-specific attack scenarios in penetration testing plans to ensure thorough security assessment of the JavaScript engine layer.