mitigations.md

Mitigation Strategies Analysis for rust-lang/cargo

Mitigation Strategy: Explicit Registry Configuration and Dependency Pinning

Description:

1. Identify Private Dependencies: List all internal or private crates.
2. Configure Private Registry (if applicable): In .cargo/config.toml (project-level or user-level), define your private registry:

   [registries]
   my-private-registry = { index = "https://my-private-registry.com/index" }

3. Specify Registry for Dependencies: In Cargo.toml, explicitly specify the registry for each private dependency:

   [dependencies]
   my-internal-crate = { version = "1.0", registry = "my-private-registry" }

   For path dependencies, use absolute paths:

   my-local-crate = { path = "/absolute/path/to/my-local-crate" }

4. Commit Cargo.lock: Always commit Cargo.lock to version control.
5. Review Cargo.lock Changes: After cargo update, carefully review the Cargo.lock diff.
6. Regularly run cargo update: Keep dependencies updated, but review changes.

• Threats Mitigated:

  • Dependency Confusion/Substitution (High Severity): Prevents malicious package injection.
  • Typosquatting (Medium Severity): Reduces risk of pulling similarly-named malicious packages.
  • Unintentional Dependency Updates (Medium Severity): Cargo.lock prevents unexpected upgrades.

• Impact:

  • Dependency Confusion/Substitution: Risk significantly reduced (almost eliminated with a private registry and scoped packages).
  • Typosquatting: Risk reduced (manual review still important).
  • Unintentional Dependency Updates: Risk significantly reduced; updates are controlled.

• Currently Implemented:

  • Cargo.lock is committed.
  • Basic Cargo.toml configuration.

• Missing Implementation:

  • Explicit registry configuration in .cargo/config.toml is missing.
  • No Cargo.lock change review process.
  • No absolute paths for local dependencies.

Mitigation Strategy: Dependency Auditing and Policy Enforcement (using cargo audit and cargo deny)

Description:

1. Integrate cargo audit: Add cargo audit to CI/CD to check for vulnerabilities. Run on every build/PR.
2. Integrate cargo deny: Add cargo deny to CI/CD to enforce policies (licenses, duplicates, etc.). Configure with .cargo/deny.toml.
3. Establish a Dependency Update Policy: Define how often to run cargo update and the review process.

• Threats Mitigated:

  • Malicious Crates (High Severity): cargo audit detects known vulnerabilities.
  • Vulnerable Dependencies (High Severity): cargo audit directly addresses this.
  • License Compliance Issues (Medium Severity): cargo deny enforces policies.
  • Code Quality Issues (Medium Severity): cargo deny can prevent problematic crates.

• Impact:

  • Malicious Crates: Risk reduced by identifying known vulnerabilities.
  • Vulnerable Dependencies: Risk significantly reduced via automated detection.
  • License Compliance Issues: Risk significantly reduced via automated enforcement.
  • Code Quality Issues: Risk reduced through policy enforcement.

• Currently Implemented:

  • Basic license checks (manual).

• Missing Implementation:

  • cargo audit not in CI/CD.
  • cargo deny not used.
  • No formal dependency update policy.

Mitigation Strategy: build.rs Script Review (using manual review and potentially cargo build flags)

Description:

1. Identify Dependencies with build.rs: List dependencies with build.rs.
2. Manual Review: Review build.rs code for:
   • Network access.
   • File system modifications outside OUT_DIR.
   • External command execution.
   • Complex/obfuscated logic.
3. cargo build --target (Limited Mitigation): Use cargo build --target ... to potentially limit the capabilities of a malicious build.rs that relies on host-specific tools. This is not a strong defense.
4. Document Findings: Document concerns.

• Threats Mitigated:

  • Malicious Build Scripts (High Severity): Reduces risk of compromised build environment.
  • Accidental Build Script Errors (Medium Severity): Helps identify unintentional errors.

• Impact:

  • Malicious Build Scripts: Risk significantly reduced through manual review. --target offers very limited mitigation.
  • Accidental Build Script Errors: Risk reduced through manual review.

• Currently Implemented:

  • None.

• Missing Implementation:

  • No build.rs review process.

Mitigation Strategy: Feature Flag Management (using Cargo.toml)

Description:

1. Identify Feature Flags: List all feature flags.
2. Explicit Feature Selection: In Cargo.toml, explicitly specify features:

   [dependencies]
   some-crate = { version = "1.0", features = ["feature1", "feature2"] }

   Avoid wildcards (features = ["*"]).
3. Document Feature Implications: Document purpose, security implications, and rationale.
4. Regular Review: Periodically review enabled flags.

• Threats Mitigated:

  • Unintentional Feature Exposure (Medium Severity): Prevents enabling vulnerable features.
  • Overly Permissive Features (Medium Severity): Ensures minimal feature set.

• Impact:

  • Unintentional Feature Exposure: Risk significantly reduced.
  • Overly Permissive Features: Risk reduced.

• Currently Implemented:

  • Some flags explicitly specified.

• Missing Implementation:

  • Not all flags explicit; some use defaults.
  • No documentation.
  • No regular review.

Mitigation Strategy: Vendoring (using cargo vendor)

Description:

1. Run cargo vendor to copy dependencies into a vendor directory.
2. Configure cargo in .cargo/config.toml:

   [source.crates-io]
   replace-with = "vendored-sources"
   
   [source.vendored-sources]
   directory = "vendor"

3. Commit the vendor directory.
4. Update by re-running cargo vendor and committing.
5. Consider cargo-vendor-filterer to reduce vendor size.

• Threats Mitigated:

  • Dependency Confusion/Substitution (High Severity): Eliminates reliance on external registries.
  • Network Outages/Registry Unavailability (Medium Severity): Builds continue offline.
  • Supply Chain Attacks (Tampering during transit) (High Severity): Dependencies pulled once.

• Impact:

  • Dependency Confusion/Substitution: Risk eliminated.
  • Network Outages/Registry Unavailability: Risk eliminated.
  • Supply Chain Attacks (Tampering during transit): Risk significantly reduced.

• Currently Implemented:

  • None

• Missing Implementation:

  • Vendoring not used; relies on external registries.