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attack-surface.md

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Attack Surface Analysis for wasmerio/wasmer

Attack Surface: 1. Malicious WebAssembly Module Execution

  • Description: A WebAssembly module, provided by an attacker or compromised source, contains malicious code designed to harm the host application or system.
  • Wasmer Contribution: Wasmer is the runtime that executes the WebAssembly module. If Wasmer doesn't properly sandbox or validate the module, malicious code can be executed.
  • Example: A seemingly innocuous WASM module, when executed by Wasmer, contains code that attempts to read files from the host filesystem outside of its intended sandbox, exploiting a potential memory escape vulnerability in Wasmer or a weakness in host function design.
  • Impact:
    • Data Breach: Access to sensitive data on the host system.
    • System Compromise: Potentially gaining control of the host system if sandboxing is completely bypassed or Wasmer itself has critical vulnerabilities.
    • Denial of Service (DoS): Resource exhaustion by the malicious module, crashing the application or system.
  • Risk Severity: High to Critical
  • Mitigation Strategies:
    • WASM Module Validation: Implement strict validation of WASM modules before loading them. Check module signatures, origins, and potentially perform static analysis to detect suspicious patterns.
    • Robust Sandboxing: Rely on Wasmer's sandboxing features and ensure they are correctly configured and up-to-date.
    • Resource Limits: Configure Wasmer to enforce resource limits (memory, CPU time) for WASM modules to prevent resource exhaustion attacks.
    • Principle of Least Privilege: Grant WASM modules only the minimum necessary permissions and access to host resources.

Attack Surface: 2. Wasmer Runtime Vulnerabilities

  • Description: Bugs or security flaws exist within the Wasmer runtime itself (e.g., in the compiler, interpreter, memory management, or API).
  • Wasmer Contribution: Wasmer is the attack surface in this case. Vulnerabilities in Wasmer directly expose applications using it.
  • Example: A buffer overflow vulnerability in Wasmer's JIT compiler is triggered by a specific sequence of WASM bytecode. An attacker crafts a WASM module to exploit this vulnerability, leading to arbitrary code execution on the host system when Wasmer attempts to compile and execute it.
  • Impact:
    • Arbitrary Code Execution: Complete compromise of the host system.
    • Memory Corruption: Application crashes, unpredictable behavior, and potential for further exploitation.
    • Denial of Service (DoS): Wasmer crashes or becomes unstable, leading to application downtime.
  • Risk Severity: Critical to High
  • Mitigation Strategies:
    • Keep Wasmer Updated: Regularly update Wasmer to the latest stable version to benefit from security patches and bug fixes.
    • Monitor Security Advisories: Subscribe to Wasmer security advisories and vulnerability databases to stay informed about known issues and apply updates promptly.
    • Security Audits: Conduct or participate in security audits of Wasmer itself and its core components to identify and address potential vulnerabilities.
    • Use Stable Versions: Prefer using stable, well-tested versions of Wasmer over development or nightly builds in production environments.

Attack Surface: 3. Sandboxing Bypasses

  • Description: Weaknesses or vulnerabilities in Wasmer's sandboxing mechanisms allow a malicious WASM module to escape the sandbox and access resources or perform actions outside of its intended isolation.
  • Wasmer Contribution: Wasmer's sandboxing is intended to isolate WASM modules. If the sandbox is flawed, Wasmer becomes the enabler of this attack surface.
  • Example: A vulnerability in Wasmer's memory isolation allows a malicious WASM module to read or write memory outside of its allocated linear memory space. This could be used to access sensitive data in the host application's memory or manipulate its state.
  • Impact:
    • Data Breach: Access to sensitive data on the host system.
    • System Compromise: Potentially gaining control of the host system if the sandbox bypass is severe enough.
    • Privilege Escalation: WASM module gaining elevated privileges within the host environment.
  • Risk Severity: High to Critical
  • Mitigation Strategies:
    • Keep Wasmer Updated: Security updates for Wasmer often include fixes for sandbox escape vulnerabilities.
    • Use Strong Sandboxing Configurations: Utilize Wasmer's sandboxing features and configure them to be as restrictive as possible, limiting access to system resources and capabilities.
    • Regular Security Audits: Conduct security audits and penetration testing to specifically look for potential sandbox escape vulnerabilities in the Wasmer integration.
    • Defense in Depth: Implement additional security layers outside of Wasmer's sandboxing, such as operating system-level security measures (e.g., seccomp, AppArmor) to further restrict the capabilities of the Wasmer process.