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Threat Model Analysis for wasmerio/wasmer

Threat: Malicious WebAssembly Module Execution

  • Description: An attacker provides a crafted WebAssembly module. When executed by Wasmer, this module performs malicious actions on the host system. This is achieved by the module directly executing harmful code within the Wasmer runtime environment.
  • Impact: Remote code execution on the host system, data breach, denial of service, system compromise.
  • Wasmer Component Affected: Module loading and execution, Wasmer runtime.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strictly validate and sign WebAssembly modules.
    • Source modules only from trusted origins.
    • Perform static and dynamic analysis of modules.
    • Utilize Wasmer's capabilities-based security to restrict module permissions.
    • Enforce resource limits within Wasmer configuration.
    • Keep Wasmer updated to the latest version.

Threat: Host Function Import Exploitation

  • Description: A malicious WebAssembly module exploits vulnerabilities in host functions that are imported and exposed to the module by Wasmer. The attacker crafts a module to call these vulnerable host functions with malicious inputs, bypassing security boundaries managed by the host application and potentially Wasmer.
  • Impact: Remote code execution on the host system, privilege escalation, data breach, system compromise.
  • Wasmer Component Affected: Host function imports, Wasmer host function interface.
  • Risk Severity: High
  • Mitigation Strategies:
    • Minimize the number of host functions exposed to Wasmer modules.
    • Thoroughly audit and secure all host function implementations.
    • Implement robust input validation within host functions before Wasmer execution.
    • Apply least privilege principle when granting host function access via Wasmer.

Threat: Wasmer Runtime Vulnerability Exploitation

  • Description: An attacker exploits a security vulnerability directly within the Wasmer runtime code itself. This could be a memory corruption bug, logic error, or other flaw in Wasmer. Exploitation is triggered through a malicious module or direct interaction with the Wasmer runtime if exposed.
  • Impact: Sandbox escape from Wasmer, remote code execution within the Wasmer process, denial of service, system instability, potential host system compromise.
  • Wasmer Component Affected: Wasmer runtime core, compiler, engine, sandbox implementation.
  • Risk Severity: Critical to High (depending on the specific vulnerability)
  • Mitigation Strategies:
    • Immediately update Wasmer to the latest patched version.
    • Monitor Wasmer security advisories for known vulnerabilities.
    • Consider static/dynamic analysis of Wasmer itself (advanced mitigation).
    • Implement robust error handling in the application using Wasmer.
    • Isolate Wasmer processes using OS-level sandboxing or containers.

Threat: Resource Exhaustion via Malicious Module (High Impact)

  • Description: A malicious WebAssembly module is designed to consume excessive resources (CPU, memory, I/O) during execution within Wasmer. This module overwhelms the host system, leading to denial of service. The attacker leverages Wasmer's execution environment to amplify resource consumption.
  • Impact: Denial of service, application unavailability, significant performance degradation, system instability.
  • Wasmer Component Affected: Module execution within Wasmer, Wasmer resource management.
  • Risk Severity: High
  • Mitigation Strategies:
    • Implement and enforce resource limits and quotas within Wasmer's configuration (memory, CPU time, etc.).
    • Actively monitor resource usage of modules running in Wasmer.
    • Implement mechanisms to automatically detect and terminate resource-intensive modules managed by Wasmer.
    • Utilize Wasmer's sandboxing features to limit resource access from modules.

Threat: Sandbox Escape via Wasmer Bug

  • Description: An attacker exploits a bug or weakness in Wasmer's sandbox implementation to escape the intended isolation. This allows a malicious WebAssembly module to bypass Wasmer's security restrictions and gain unauthorized access to the host system, executing code outside of the sandboxed Wasmer environment.
  • Impact: Full compromise of the host system, remote code execution outside the Wasmer sandbox, data breach, complete system control.
  • Wasmer Component Affected: Wasmer sandbox implementation, security boundaries, Wasmer runtime core.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Maintain Wasmer at the latest version with all security patches applied.
    • Utilize all available Wasmer security features and configuration options to strengthen the sandbox.
    • Minimize privileges granted to the Wasmer process at the operating system level.
    • Implement defense-in-depth using OS-level sandboxing or containerization around Wasmer.
    • Conduct regular security audits and penetration testing focusing on Wasmer's sandbox.