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attack-surface.md

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Attack Surface Analysis for dotnet/roslyn

Attack Surface: Code Injection via Dynamic Compilation

  • Description: Applications using Roslyn to dynamically compile code from untrusted input are vulnerable to attackers injecting malicious code that gets compiled and executed.
  • Roslyn Contribution: Roslyn provides the core functionality for dynamic compilation of C# and VB.NET code, enabling this attack surface when used with untrusted input.
  • Example: A web application uses user input to construct and execute dynamic C# code for custom workflows. An attacker injects malicious C# code into the input, leading to unauthorized actions when compiled and executed by Roslyn.
  • Impact: Full application compromise, remote code execution, data breach, unauthorized access to system resources.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict Input Validation and Sanitization: Thoroughly validate and sanitize all user inputs before incorporating them into code strings for dynamic compilation. Employ whitelisting and escape special characters.
    • Avoid Dynamic Compilation with Untrusted Input: Re-evaluate the necessity of dynamic compilation with untrusted input. Explore safer alternatives like pre-defined logic or configuration-based approaches.
    • Sandboxing and Isolation: Execute dynamically compiled code within a secure sandbox environment with restricted permissions to limit the impact of successful injection.
    • Principle of Least Privilege: Run the application with minimal necessary privileges to contain potential damage from code injection.

Attack Surface: Denial of Service (DoS) through Compiler Resource Exhaustion

  • Description: Maliciously crafted code or repeated compilation requests can exhaust server resources (CPU, memory, I/O) via Roslyn's compilation process, leading to application unavailability.
  • Roslyn Contribution: Roslyn's compilation process, especially for complex or large codebases, is inherently resource-intensive. This resource consumption can be exploited to launch DoS attacks.
  • Example: An online code testing platform using Roslyn allows users to compile and run code. An attacker submits extremely complex or deeply nested code, or floods the server with compilation requests, overwhelming server resources and causing service disruption for legitimate users.
  • Impact: Application downtime, service unavailability, resource exhaustion, financial losses due to service disruption.
  • Risk Severity: High
  • Mitigation Strategies:
    • Resource Limits and Quotas: Implement strict resource limits (CPU time, memory, compilation time) for compilation processes.
    • Rate Limiting and Throttling: Limit the number of compilation requests from a single user or IP address within a given timeframe.
    • Input Size and Complexity Limits: Restrict the size and complexity of code inputs allowed for compilation to prevent excessively resource-intensive tasks.
    • Asynchronous Compilation: Offload compilation tasks to background threads or separate processes to prevent blocking the main application thread and improve responsiveness.
    • Caching of Compilation Results: Cache compilation outputs where applicable to reduce redundant compilations and resource usage.

Attack Surface: Deserialization Vulnerabilities in Compilation Artifacts

  • Description: Deserializing Roslyn compilation artifacts (like syntax trees or semantic models) from untrusted sources can lead to deserialization vulnerabilities, potentially enabling remote code execution.
  • Roslyn Contribution: Roslyn provides mechanisms to serialize and deserialize compilation-related objects for caching or inter-process communication. This functionality becomes a vulnerability point when handling untrusted serialized data.
  • Example: An application caches compiled code by serializing Roslyn's compilation objects. If this cache is stored in a shared location and an attacker replaces the cached artifacts with maliciously crafted serialized data, deserialization by the application could execute arbitrary code.
  • Impact: Remote code execution, full application compromise, data corruption, potential for persistent attacks through cache poisoning.
  • Risk Severity: High
  • Mitigation Strategies:
    • Avoid Deserialization of Untrusted Data: Never deserialize Roslyn compilation artifacts from untrusted or unauthenticated sources.
    • Input Validation for Serialized Data (If unavoidable): If deserialization from potentially untrusted sources is unavoidable, implement rigorous input validation and sanitization on the serialized data before deserialization.
    • Secure Serialization Practices: Utilize secure serialization formats and libraries that are less susceptible to deserialization vulnerabilities.
    • Integrity Checks and Signing: Implement integrity checks and digital signatures for serialized compilation artifacts to verify their authenticity and prevent tampering.

Attack Surface: Compiler Bugs and Vulnerabilities within Roslyn itself

  • Description: Bugs or vulnerabilities within Roslyn's parsing, semantic analysis, code generation, or other core components can be exploited to bypass security measures or cause unexpected and potentially harmful behavior.
  • Roslyn Contribution: As a complex software platform, Roslyn, like any other software, may contain inherent bugs or vulnerabilities that could be discovered and exploited.
  • Example: A vulnerability in Roslyn's code parsing logic allows an attacker to craft specific C# code that bypasses security checks during compilation, leading to the execution of malicious code within the application's context despite intended security measures.
  • Impact: Remote code execution, security bypass, application instability, data corruption, potential for privilege escalation.
  • Risk Severity: High to Critical (depending on the specific vulnerability)
  • Mitigation Strategies:
    • Keep Roslyn Updated: Maintain Roslyn at the latest stable version to benefit from security patches and bug fixes. Regularly monitor security advisories and release notes.
    • Security Vulnerability Scanning: Include Roslyn and its dependencies in routine security vulnerability scanning processes.
    • Report Potential Vulnerabilities: If you discover a potential security vulnerability in Roslyn, promptly report it to the .NET security team through their responsible disclosure channels.
    • Defense in Depth: Implement multiple layers of security in your application to mitigate the impact of potential vulnerabilities in Roslyn or any other single component.

Attack Surface: Abuse of Scripting Capabilities (if enabled)

  • Description: If Roslyn's scripting APIs are enabled and exposed without proper security controls, attackers can abuse them to execute arbitrary code within the application's context, bypassing intended security boundaries.
  • Roslyn Contribution: Roslyn's scripting APIs provide powerful dynamic code execution capabilities, which, if not secured, can be misused to execute malicious scripts.
  • Example: An application exposes a scripting endpoint using Roslyn's scripting APIs for extensibility or automation. An attacker exploits a lack of authentication or authorization on this endpoint to execute malicious scripts, gaining unauthorized access to application data or resources, or even the underlying system.
  • Impact: Remote code execution, unauthorized access, data breach, full application compromise, potential for lateral movement within the network.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Disable Scripting if Unnecessary: If scripting capabilities are not essential for the application's core functionality, disable them entirely to eliminate this attack surface.
    • Strong Authentication and Authorization: Implement robust authentication and authorization mechanisms for accessing scripting endpoints. Ensure only authorized users or processes can execute scripts.
    • Strict Input Validation and Sanitization for Scripts: Thoroughly validate and sanitize all inputs to scripting APIs to prevent code injection within scripts themselves.
    • Principle of Least Privilege for Scripts: Execute scripts with the minimum necessary permissions required for their intended functionality.
    • Script Sandboxing and Isolation: Execute scripts within a secure sandbox environment with restricted access to system resources, sensitive data, and network access.
    • Regular Security Audits of Scripting Features: Conduct regular security audits and penetration testing specifically focused on the application's scripting features and their security controls.

Attack Surface: Dependency Vulnerabilities in Roslyn's Dependencies

  • Description: Vulnerabilities in third-party libraries and packages that Roslyn depends on can indirectly create attack surfaces in applications using Roslyn.
  • Roslyn Contribution: Roslyn relies on a set of .NET libraries and NuGet packages. Vulnerabilities in these dependencies can propagate and affect applications that utilize Roslyn.
  • Example: A vulnerability is discovered in a NuGet package used by Roslyn for XML processing. An attacker exploits this vulnerability through Roslyn by providing specially crafted input that triggers the vulnerable code path within the dependency, even if the application code itself is not directly using XML processing.
  • Impact: Varies depending on the specific dependency vulnerability, but can range from information disclosure and DoS to remote code execution.
  • Risk Severity: High
  • Mitigation Strategies:
    • Software Composition Analysis (SCA): Implement SCA tools and processes to continuously monitor Roslyn's dependencies for known vulnerabilities.
    • Regular Dependency Updates: Keep Roslyn and all its dependencies updated to the latest versions to patch known vulnerabilities. Establish a process for timely patching of dependency vulnerabilities.
    • Dependency Pinning and Management: Use dependency pinning or locking mechanisms to ensure consistent and controlled dependency versions.
    • Vulnerability Scanning in CI/CD Pipeline: Integrate dependency vulnerability scanning into the CI/CD pipeline to detect vulnerabilities early in the development lifecycle.