mitigations.md

Mitigation Strategies Analysis for jenkinsci/pipeline-model-definition-plugin

Mitigation Strategy: Strict Jenkinsfile Source Control

Description:

1. Establish a Git Repository: The Jenkinsfile (which defines the Declarative Pipeline) must be stored in a Git repository.
2. Branching Model: Use a branching model (e.g., Gitflow) with feature branches and pull requests for merging to the main branch.
3. Branch Protection: Configure branch protection on main:
   • Require pull request reviews.
   • Require status checks (builds, tests).
   • Restrict direct pushes.
4. Code Reviews: Mandatory code reviews for all Jenkinsfile changes, specifically checking for:
   • Code injection in Groovy.
   • Secret exposure.
   • script block misuse.
   • Parameter misuse.
   • when condition logic.
5. Commit Signing (Recommended): Developers sign commits (GPG/SSH).
6. Regular Access Audits: Review repository access and permissions.

• Threats Mitigated:

  • Code Injection (Severity: Critical): Prevents direct injection of malicious Groovy code into the Jenkinsfile.
  • Unauthorized Changes (Severity: High): Ensures all Jenkinsfile changes are reviewed/approved.
  • Compromised Developer Accounts (Severity: High): Limits the impact of compromised accounts on the Jenkinsfile.

• Impact:

  • Code Injection: Risk significantly reduced (Critical to Low/Medium).
  • Unauthorized Changes: Risk significantly reduced (High to Low).
  • Compromised Accounts: Impact mitigated.

• Currently Implemented:

  • Example: "Implemented for infrastructure-pipelines repo. Branch protection on main, one reviewer required, CI checks enforced. Code reviews mandatory."

• Missing Implementation:

  • Example: "Commit signing not implemented. Access audits ad-hoc. application-pipelines repo lacks branch protection."

Mitigation Strategy: Parameter Sanitization and Validation (within the Pipeline)

Description:

1. Identify All Parameters: List all parameters the pipeline accepts.
2. Define Expected Types: Determine data type and constraints for each parameter.
3. Implement Validation (in Groovy):
   • String: Use regular expressions (e.g., ^[a-zA-Z0-9]+$).
   • Integer: Parse as integer, use try-catch.
   • Boolean: Accept "true"/"false" (case-insensitive).
   • Choice: Define allowed values.
   • Avoid Direct Interpolation: Never directly embed parameters in shell/Groovy without escaping/sanitization.
4. Safe params Object Use: Access via params, be aware of types, use type-safe methods.
5. Reject Invalid Input: Fail build or use a safe default.
6. Input Sanitization (Groovy): If input is used as code (HTML, SQL), sanitize it (HTML escaping, URL encoding, etc., using Groovy libraries).

• Threats Mitigated:

  • Code Injection (Severity: Critical): Prevents injecting malicious code via pipeline parameters.
  • Cross-Site Scripting (XSS) (Severity: High): Mitigates XSS if input is displayed (relevant for input step).
  • Unexpected Behavior (Severity: Medium): Prevents unexpected behavior from invalid input.

• Impact:

  • Code Injection: Risk significantly reduced (Critical to Low/Medium).
  • XSS: Risk significantly reduced (High to Low).
  • Unexpected Behavior: Risk reduced (Medium to Low).

• Currently Implemented:

  • Example: "Basic validation in deploy-application pipeline using regex, but not consistent."

• Missing Implementation:

  • Example: "Comprehensive validation missing in build-image pipeline. XSS sanitization missing for input steps."

Mitigation Strategy: Limit the Use of script Blocks

Description:

1. Prefer Declarative Directives: Use built-in directives (agent, stages, steps, post, etc.) over script blocks.
2. Minimize script Block Code: If unavoidable, keep script blocks short and simple.
3. Justify and Review: Every script block must be justified in a comment and thoroughly reviewed, assessing:
   • Could it be a Declarative directive?
   • Security implications of the code.
   • Code injection potential.
4. Isolate script Blocks: If interacting with sensitive data, isolate in a separate stage, use withCredentials.

• Threats Mitigated:

  • Code Injection (Severity: Critical): Reduces the attack surface for Groovy code injection.
  • Increased Complexity (Severity: Medium): Makes the pipeline easier to understand, reducing vulnerability likelihood.

• Impact:

  • Code Injection: Risk reduced (Critical to Medium/High).
  • Increased Complexity: Complexity reduced.

• Currently Implemented:

  • Example: "Team encouraged to use Declarative directives, but no formal policy. Older pipelines use many script blocks."

• Missing Implementation:

  • Example: "Formal review process for script blocks missing. No automated check for excessive use."

Mitigation Strategy: Secure Secret Management (within the Pipeline)

Description:

1. Jenkins Credentials Plugin: All secrets (passwords, API keys, etc.) must be stored using the Jenkins Credentials plugin. Never hardcode.
2. Appropriate Credential Type: Use the correct type (Secret text, Username with password, etc.).
3. withCredentials Binding: Use withCredentials to bind secrets to environment variables only within the stage they are needed.
4. Avoid Echoing: Do not print secret environment variables.
5. Mask Passwords (Global Setting): Enable "Mask Passwords" in Jenkins global configuration.
6. Regular Rotation: Rotate secrets and update Jenkins credentials.
7. Least Privilege: Grant access to credentials only to the pipelines and users that require them.

• Threats Mitigated:

  • Secret Exposure (Severity: Critical): Prevents exposure in Jenkinsfile, logs, or environment.
  • Credential Theft (Severity: High): Reduces impact by limiting scope and rotating secrets.

• Impact:

  • Secret Exposure: Risk significantly reduced (Critical to Low).
  • Credential Theft: Impact reduced.

• Currently Implemented:

  • Example: "Credentials plugin used. withCredentials mostly used, but inconsistencies exist."

• Missing Implementation:

  • Example: "Secret rotation not automated. 'Mask Passwords' not enabled. Older pipelines may have hardcoded secrets."

Mitigation Strategy: Controlled Shared Library Usage (with Declarative)

Description:

1. Secure Shared Library Repo: Separate, secure Git repo, same controls as Jenkinsfile repo.
2. Version Control: Semantic versioning. Pipelines specify the exact version (e.g., @Library('[email protected]') _).
3. Code Reviews: Rigorous code reviews for shared libraries, focusing on security.
4. Dependency Management: Scan for vulnerabilities in dependencies (OWASP Dependency-Check, Snyk).
5. Restrict Access: Limit which pipelines can load specific libraries.
6. Testing: Thorough unit/integration tests for shared libraries.
7. Secure Loading: Ensure libraries are loaded from a trusted source and integrity is verified.

• Threats Mitigated:

  • Code Injection (Severity: Critical): Prevents malicious code via compromised shared libraries.
  • Dependency Vulnerabilities (Severity: High): Reduces risk from vulnerable dependencies.
  • Unauthorized Code Execution (Severity: High): Prevents unauthorized pipelines from using privileged libraries.

• Impact:

  • Code Injection: Risk significantly reduced (Critical to Low/Medium).
  • Dependency Vulnerabilities: Risk reduced (High to Medium/Low).
  • Unauthorized Code Execution: Risk reduced (High to Low).

• Currently Implemented:

  • Example: "Shared libraries in separate Git repo, code reviews required. Versioning used, but not always enforced."

• Missing Implementation:

  • Example: "Dependency scanning not automated. Access controls for libraries not configured. Limited testing."

Mitigation Strategy: Simple and Secure when Conditions

Description:

1. Prefer Built-in Conditions: Use built-in when conditions (branch, environment, etc.) over custom Groovy.
2. Keep it Simple: Avoid complex, nested when conditions. Refactor to shared library functions if needed (with security).
3. Avoid Untrusted Input: Do not use user input directly in when conditions, especially expression. Validate/sanitize first.
4. Thorough Testing: Test when conditions extensively with various inputs.
5. Code Review Focus: Reviews must examine when conditions for logic errors, bypasses, injection.

• Threats Mitigated:

  • Logic Errors/Bypasses (Severity: Medium/High): Prevents unintended stage execution/skipping.
  • Code Injection (Severity: Critical): Reduces risk if input is used in when (especially expression).

• Impact:

  • Logic Errors/Bypasses: Risk reduced (Medium/High to Low).
  • Code Injection: Risk reduced (Critical to Low/Medium).

• Currently Implemented:

  • Example: "No specific guidelines on when condition complexity."

• Missing Implementation:

  • Example: "Code reviews don't consistently focus on when security. No automated check for complex/vulnerable conditions."

Mitigation Strategy: Secure input Step Configuration (within the Pipeline)

Description:

1. Sanitize Input (Groovy): Always sanitize user input from input before using it where it could be interpreted as code.
   • HTML Escaping: Use StringEscapeUtils or similar for web display.
   • URL Encoding: For URLs.
   • Shell Escaping: For shell commands (avoid direct interpolation; use parameters).
2. Restrict Input Types: Use specific types (choice, booleanParam, password) over string.
3. Validate Input (Groovy): Implement validation rules, even with sanitization.
4. Limit Input Scope: Use input only in specific stages where necessary.
5. Avoid Sensitive Data: Do not use input for secrets. Use Credentials plugin.
6. Timeout: Set a reasonable timeout for the input step.

• Threats Mitigated:

  • Cross-Site Scripting (XSS) (Severity: High): Prevents injecting JavaScript via input.
  • Code Injection (Severity: Critical): Prevents injecting code (e.g., shell) via input.
  • Denial of Service (DoS) (Severity: Medium): Timeout prevents indefinite blocking.

• Impact:

  • XSS: Risk significantly reduced (High to Low).
  • Code Injection: Risk significantly reduced (Critical to Low/Medium).
  • DoS: Risk reduced (Medium to Low).

• Currently Implemented:

  • Example: "input used in a few pipelines, but sanitization inconsistent."

• Missing Implementation:

  • Example: "No HTML escaping or sanitization for input data. Validation is basic."