Injection

Injection Analysis (OWASP A03:2021)

Analyze source code for injection vulnerabilities where user-supplied data flows into interpreters without proper validation, sanitization, or parameterization. This is the most code-scannable OWASP category -- most injection patterns leave clear syntactic fingerprints in source code.

Supported Flags

Read ../../shared/schemas/flags.md for the full flag specification. This skill supports all cross-cutting flags. Key behaviors:

Framework Context

OWASP A03:2021 - Injection

User-supplied data is not validated, filtered, or sanitized by the application. Dynamic queries or commands are constructed using string concatenation or interpolation with hostile data. Common injection types:

• SQL Injection (CWE-89): Unsanitized input in SQL queries
• NoSQL Injection (CWE-943): Unsanitized input in MongoDB/NoSQL queries
• OS Command Injection (CWE-78): User input passed to system shell commands
• LDAP Injection (CWE-90): Unsanitized input in LDAP queries
• Expression Language Injection (CWE-917): User input in EL/template engines
• ORM Injection (CWE-89): Raw queries or unsafe ORM usage with user input

STRIDE Mapping: Tampering, Information Disclosure, Elevation of Privilege

Detection Patterns

Read references/detection-patterns.md for the full pattern catalog with language-specific examples, regex heuristics, and false positive guidance.

Pattern Summary:

1. String concatenation in SQL queries
2. Template string / f-string SQL construction
3. Raw ORM queries with user input
4. os.system / exec / subprocess with user input
5. eval() / Function() with user input
6. LDAP query string construction with user input

Workflow

Step 1: Determine Scope

1. Parse --scope flag (default: changed).
2. Resolve to a concrete file list.
3. Filter to relevant file types: .py, .js, .ts, .jsx, .tsx, .java, .go, .rb, .php, .cs, .rs, .kt, .scala, .sql, .graphql.
4. Prioritize files containing: database query patterns, HTTP handler functions, system call imports, LDAP library usage, eval/exec constructs.

Step 2: Check for Scanners

Detect available scanners in priority order:

Record which scanners are available and which are missing. If none are available, note: "No scanner available -- findings based on code pattern analysis only."

Step 3: Run Scanners

For each available scanner, run against the scoped files:

semgrep scan --config auto --json --quiet <target>
bandit -r <target> -f json -q
gosec -fmt json ./...

Normalize scanner output to the findings schema (see ../../shared/schemas/findings.md). Use the severity mapping from ../../shared/schemas/scanners.md.

Step 4: Claude Analysis

Read each scoped file and analyze for injection patterns not caught by scanners:

1. Identify sinks: Database query functions, system calls, LDAP operations, eval/exec, template engines.
2. Trace sources: HTTP request parameters, form data, URL path segments, headers, cookies, file uploads, environment variables from user input.
3. Check sanitization: Is there parameterization, input validation, allowlisting, or escaping between source and sink?
4. Assess context: Is the code reachable from an external entry point? Is there framework-level protection (e.g., Django ORM, prepared statements)?
5. Deduplicate: Merge Claude findings with scanner findings. If both found the same issue, keep the scanner finding and add Claude's context.

At --depth deep or --depth expert, trace data flow across files:

• Follow function calls from HTTP handlers to database/system call sites.
• Check middleware and interceptors for global sanitization.
• Map the full taint path: source -> transforms -> sink.

Step 5: Report

Output findings using the format from ../../shared/schemas/findings.md.

Each finding must include:

• id: INJ-001, INJ-002, etc.
• title: Concise description of the injection type and location.
• severity: Based on exploitability, authentication requirements, and impact.
• location: File, line, function, and vulnerable code snippet.
• description: What is vulnerable and why.
• impact: What an attacker can achieve.
• fix: Parameterized/safe replacement code.
• references: CWE, OWASP A03:2021, STRIDE mapping.

What to Look For

These are the primary injection patterns to detect. Each has detailed examples and regex heuristics in references/detection-patterns.md.

1. String concatenation in SQL: "SELECT * FROM users WHERE id = " + userId
2. Template literals in SQL: `SELECT * FROM users WHERE id = ${userId}`
3. F-strings / format strings in SQL: f"SELECT * FROM users WHERE id = {user_id}"
4. Raw ORM queries: Model.objects.raw(user_input), sequelize.query(userInput)
5. OS command construction: os.system("ping " + host), exec("ls " + dir)
6. subprocess with shell=True: subprocess.call(cmd, shell=True) where cmd includes user input
7. eval/exec with user input: eval(request.body), new Function(userCode)()
8. LDAP filter construction: "(uid=" + username + ")" without escaping
9. NoSQL operator injection: db.users.find({username: req.body.username}) where body can contain $gt, $ne
10. Stored procedures with concatenation: Dynamic SQL inside stored procedures

Scanner Integration

Primary: semgrep (broadest injection coverage across languages) Language-specific: bandit (Python), gosec (Go), brakeman (Rails), spotbugs (Java) Fallback: Grep regex patterns from references/detection-patterns.md

When scanners are available, run them first and use Claude analysis to:

• Validate scanner findings (reduce false positives).
• Find injection patterns scanners miss (complex data flows, indirect concatenation).
• Provide fix suggestions with parameterized replacements.

When no scanners are available, Claude performs full pattern-based analysis using the Grep heuristics from references/detection-patterns.md and contextual code reading. Report these findings with confidence: medium.

Output Format

Use finding ID prefix INJ (e.g., INJ-001, INJ-002).

All findings follow the schema in ../../shared/schemas/findings.md with:

• references.owasp: "A03:2021"
• references.stride: "T" (Tampering), "I" (Info Disclosure), or "E" (Elevation of Privilege)
• metadata.tool: "injection"
• metadata.framework: "owasp"
• metadata.category: "A03"

CWE Mapping by Injection Type:

Summary Table

After all findings, output a summary:

| Injection Type | Critical | High | Medium | Low |
|---------------|----------|------|--------|-----|
| SQL            |          |      |        |     |
| OS Command     |          |      |        |     |
| NoSQL          |          |      |        |     |
| eval/exec      |          |      |        |     |
| LDAP           |          |      |        |     |
| ORM            |          |      |        |     |

Followed by: top 3 priorities, scanner coverage notes, and overall assessment.