CodeQL

Project Layout

.github/codeql/
├── codeql-config.yml                  # Main config (paths-ignore, packs, query-filters)
├── custom-queries/
│   ├── qlpack.yml                     # QL pack definition (name: kibana-custom-queries)
│   ├── codeql-pack.lock.yml
│   ├── suppression/                   # Alert suppression logic
│   │   ├── AlertSuppression.ql
│   │   └── AlertSuppression.qll
│   └── <category>/                    # e.g. dos/, xss/
│       ├── <RuleName>.ql             # Query file
│       ├── <RuleName>.qhelp          # Help docs (XML)
│       ├── <RuleName>.md             # Human-readable docs
│       ├── <category>-security.qls   # Query suite
│       └── <RuleName>/              # Unit test directory
│           ├── <RuleName>.qlref      # Points to the .ql file (relative to qlpack root)
│           ├── <RuleName>.expected   # Expected test output
│           └── test.js               # Test source code
scripts/codeql/
├── quick_check.sh                     # Local analysis via Docker
└── codeql.dockerfile                  # Docker image (ubuntu + CodeQL CLI)

Running Queries Locally (Full Analysis)

Uses Docker to create a CodeQL database and run queries against real source code.

# Analyze a source directory with custom queries
bash scripts/codeql/quick_check.sh -s <source_dir> -q .github/codeql/custom-queries

# Analyze with a single query file
bash scripts/codeql/quick_check.sh -s <source_dir> -q .github/codeql/custom-queries/dos/UnboundedArrayInRoute.ql

# Custom results directory
bash scripts/codeql/quick_check.sh -s <source_dir> -r .codeql-results -q .github/codeql/custom-queries

Options:

• -s <source_dir> (required for analysis): directory to scan
• -q <query_dir|query_file>: custom queries directory or single .ql file
• -r <results_dir>: where to store DB and SARIF (default: .codeql/)
• -t: run unit tests instead of analysis (use with -q, no -s needed)

Output: SARIF file at <results_dir>/database/results.sarif. If jq is installed, a colored summary prints automatically.

First run builds a Docker image (codeql-env) from scripts/codeql/codeql.dockerfile. On Apple Silicon, it runs with --platform linux/amd64 (emulation).

Running CodeQL Unit Tests

Unit tests validate that a query flags the correct lines. Each test lives in a subdirectory named after the query.

Test structure

<category>/<RuleName>/
├── <RuleName>.qlref       # Reference: "category/RuleName.ql"
├── test.js                # Source code with `// $ Alert` annotations
└── <RuleName>.expected    # Expected output (auto-generated or hand-written)

• // $ Alert on a line means the query should flag that line
• Lines without // $ Alert should not be flagged
• .expected file has pipe-delimited format: | <location> | <message> |

Running tests via Docker

Uses the same codeql-env Docker image built by quick_check.sh (built automatically on first run).

# Run a specific test directory
bash scripts/codeql/quick_check.sh -t -q .github/codeql/custom-queries/dos/UnboundedArrayInRoute

# Run all tests in the qlpack
bash scripts/codeql/quick_check.sh -t -q .github/codeql/custom-queries

CI workflow

The codeql-pr.yml workflow automatically runs unit tests on PR. It finds all *.qlref directories and runs codeql test run against them.

Fetching Remote SARIF / Scan Results

The scripts/fetch_sarif.mjs script (relative to this skill directory) fetches CodeQL SARIF results and alerts from GitHub for a PR or branch.

# By PR number
GITHUB_TOKEN=ghp_xxx node .agents/skills/codeql/scripts/fetch_sarif.mjs 252121

# By full ref
GITHUB_TOKEN=ghp_xxx node .agents/skills/codeql/scripts/fetch_sarif.mjs refs/heads/main

Requires: GITHUB_TOKEN env var with security_events scope. Depends on @octokit/rest (already in Kibana deps).

What it does:

1. Lists recent CodeQL analyses for the ref
2. Fetches full SARIF JSON (with rule severity cross-referencing)
3. Prints formatted results (rule, severity, message, file:line)
4. Fetches code scanning alerts for the same ref

Writing a New Query

1. Create the .ql file in .github/codeql/custom-queries/<category>/:

   • Use @id js/kibana/<descriptive-id> (must be unique)
   • Include @kind problem (or path-problem for taint tracking)
   • Set @problem.severity and @security-severity
   • Import javascript module
   • Refer to existing queries like UnboundedArrayInRoute.ql for patterns

2. Create a unit test directory <category>/<RuleName>/:

   • <RuleName>.qlref containing <category>/<RuleName>.ql
   • test.js with annotated test cases (// $ Alert for expected hits)
   • Run tests to generate .expected — verify it matches expectations

3. Add a .qhelp (XML) and/or .md for documentation

4. Optionally add a .qls query suite if grouping multiple queries

5. Test locally with quick_check.sh against real Kibana source code

Inline Suppressions

Suppressions use the format // codeql[rule-id] justification text. Every suppression must include a specific justification explaining why it is safe.

Valid:

// codeql[js/path-injection] User input is validated against an allowlist before use
return fs.readFileSync(`/etc/${validatedPath}`, 'utf8');

Invalid — flag these:

• Missing justification: // codeql[js/path-injection] with no explanation
• Generic justification: "false positive", "safe", "not a vulnerability" — says nothing about the actual mitigation
• Incomplete justification: "sanitized" — does not explain how or by what mechanism

Good justifications describe the concrete security mechanism: allowlist validation, DOMPurify escaping, shell-quote library, test-only code, etc.

Troubleshooting

References

• Writing CodeQL queries — official guide covering query structure, QL tutorials, and running queries