Bandit Sast

Bandit SAST

This skill performs static application security testing (SAST) for Python projects using Bandit, identifying common security anti-patterns such as use of dangerous functions, hardcoded credentials, insecure cryptography, and injection risks, then mapping findings to CWE and OWASP Top 10:2021 standards.

When to Use

• When the user asks to "scan Python code for security issues" or "run Bandit"
• When the user mentions "Python SAST" or "security scan Python"
• When reviewing Python code for vulnerabilities before deployment
• When a pull request contains changes to .py files and a security check is requested
• When the user asks to find insecure patterns like eval, exec, pickle, or hardcoded passwords in Python

When NOT to Use

• When scanning non-Python code (JavaScript, Go, Java, etc.) — you MUST decline and recommend semgrep-rule-creator or the language-specific tool instead
• When the user is asking about Python code style, formatting, or linting — you MUST decline and recommend pylint or flake8
• When the user wants runtime or dynamic analysis of a running application — you MUST decline and recommend DAST tools like dast-nuclei
• When the user wants to generate security test code — you MUST decline and recommend security-test-generator
• When the user wants a CI/CD security pipeline — you MUST decline and recommend devsecops-pipeline
• When the security-review skill already covers the request at a general level and no Python-specific SAST depth is needed

Prerequisites

Tool Installed (Preferred)

# Detection
which bandit || python -m bandit --version

# Installation (if not found)
pip install bandit

Minimum version: Bandit 1.7+. No API key required.

Tool Not Installed (Fallback)

> Note: This is a limited review. Install Bandit for comprehensive scanning with full test coverage.

When Bandit is not available, perform these top-10 manual Python security checks:

1. eval() / exec() usage — Search for eval( and exec( calls, especially with user-controlled input
2. subprocess with shell=True — Search for subprocess.call(, subprocess.Popen(, subprocess.run( with shell=True and string interpolation
3. Hardcoded passwords — Search for variables named password, passwd, secret, api_key assigned to string literals
4. pickle deserialization — Search for pickle.loads(, pickle.load(, cPickle.load( on untrusted data
5. Weak hashing — Search for hashlib.md5(, hashlib.sha1( used for password hashing or security-sensitive operations
6. assert in production — Search for assert statements used for input validation (stripped in optimized mode)
7. Wildcard imports — Search for from module import * which can mask injected names
8. try-except-pass — Search for bare except: or except Exception: followed by pass, which silences security errors
9. Insecure temp files — Search for tempfile.mktemp( (use tempfile.mkstemp() or NamedTemporaryFile instead)
10. yaml.load() without SafeLoader — Search for yaml.load( without Loader=yaml.SafeLoader or yaml.safe_load(

Workflow

> MANDATORY FIRST ACTION — Verify the tool before reporting its output. > > Your first Bash call must be command -v bandit || bandit --version. Branch on the result: > > - Bandit is available — proceed with the installed-tool workflow (step 3a below). The report may use ## Bandit SAST Scan Results, cite B-series test IDs (B101, B602, etc.), and reference the Bandit version, because real Bandit output backs all of it. > - Bandit is not available — proceed with the fallback workflow (step 3b below). The report must: > - Use header ## Python Security Review (Manual Fallback). > - Open with: > Note: This is a limited review. Install Bandit for comprehensive scanning. > - Cite CWE + OWASP only. B-series test IDs are Bandit's internal taxonomy — using them without running Bandit misattributes the findings to a tool that did not produce them. > - Not claim a scanner, version, or file count that the turn history doesn't show. > > The contract is simple: every artifact in the report must trace back to something the skill actually did in this turn. If you did not run bandit, don't present Bandit results. The user is relying on the report matching what was actually scanned.

1. Detect Python project — Confirm Python files exist by checking for *.py files, requirements.txt, setup.py, pyproject.toml, or Pipfile.
2. Check for Bandit — Run which bandit || python -m bandit --version to determine if Bandit is installed.
3. If Bandit is installed:

a. Run bandit -r . -f json -q to scan all Python files recursively with JSON output. b. Parse the JSON output — each result contains test_id, test_name, issue_severity, issue_confidence, issue_text, filename, and line_number. c. Map each test_id to its CWE using the Reference Tables below. d. Map each CWE to its OWASP Top 10:2021 category.

1. If Bandit is NOT installed:

a. Offer to install via pip install bandit. b. If the user declines, run the 10 manual fallback checks listed in Prerequisites. c. Include the disclaimer: "This is a limited review. Install Bandit for comprehensive scanning."

1. Compile findings — Deduplicate results and sort by severity: Critical > High > Medium > Low.
2. Generate report — Present findings using the Findings Format below.
3. Summarize — State total findings, breakdown by severity, and top 3 remediation priorities.

Findings Format

> MANDATORY FORMAT: You MUST include Severity, CWE, and OWASP Top 10:2021 mapping on every finding. Use the exact table format shown below — do not use freeform text.

Each finding should include:

| Field | Description | |-------|-------------| | Severity | Critical / High / Medium / Low | | CWE | CWE-XXX identifier | | OWASP | A01-A10 category (OWASP Top 10:2021) | | Location | file:line | | Issue | Description of the vulnerability | | Remediation | How to fix it |

Example Finding

| Field | Value | |-------|-------| | Severity | High | | CWE | CWE-78 | | OWASP | A03:2021 - Injection | | Location | app/utils.py:27 | | Issue | subprocess.call() with shell=True and f-string user input enables OS command injection | | Remediation | Use subprocess.run() with a list of arguments and shell=False (default) |

Reference Tables

Bandit Test ID to CWE Mapping

| Bandit Test ID | Test Name | CWE | OWASP | Default Severity | |----------------|-----------|-----|-------|------------------| | B101 | assertused | CWE-703 | A07:2021 - Security Misconfiguration | Low | | B102 | execused | CWE-78 | A03:2021 - Injection | Medium | | B301 | pickle | CWE-502 | A08:2021 - Software and Data Integrity Failures | Medium | | B303 | md5 / sha1 | CWE-328 | A02:2021 - Cryptographic Failures | Medium | | B306 | mktempq | CWE-377 | A01:2021 - Broken Access Control | Medium | | B307 | eval | CWE-78 | A03:2021 - Injection | Medium | | B501 | requestwithnocertvalidation | CWE-295 | A07:2021 - Security Misconfiguration | High | | B602 | subprocesspopenwithshellequalstrue | CWE-78 | A03:2021 - Injection | High | | B603 | subprocesswithoutshellequalstrue | CWE-78 | A03:2021 - Injection | Low | | B608 | hardcodedsqlexpressions | CWE-89 | A03:2021 - Injection | Medium | | B105 | hardcodedpasswordstring | CWE-259 | A07:2021 - Security Misconfiguration | Low | | B106 | hardcodedpasswordfuncarg | CWE-259 | A07:2021 - Security Misconfiguration | Low | | B403 | importpickle | CWE-502 | A08:2021 - Software and Data Integrity Failures | Low | | B506 | yamlload | CWE-502 | A08:2021 - Software and Data Integrity Failures | Medium |

OWASP Top 10:2021 Quick Reference

| Category | Description | Common CWEs | |----------|-------------|-------------| | A01:2021 | Broken Access Control | CWE-377 | | A02:2021 | Cryptographic Failures | CWE-328 | | A03:2021 | Injection | CWE-78, CWE-89 | | A07:2021 | Security Misconfiguration | CWE-259, CWE-295, CWE-703 | | A08:2021 | Software and Data Integrity Failures | CWE-502 |

Example Usage

With Bandit Installed

User prompt: > "Run a Bandit scan on this Python project"

Expected output (abbreviated):

## Bandit SAST Scan Results

Scanned 14 files in src/

### Findings (4 total: 0 Critical, 2 High, 1 Medium, 1 Low)

| # | Severity | CWE | OWASP | Location | Issue |
|---|----------|-----|-------|----------|-------|
| 1 | High | CWE-78 | A03 | src/deploy.py:31 | subprocess.Popen() with shell=True and user input (B602) |
| 2 | High | CWE-78 | A03 | src/utils.py:12 | eval() called with user-supplied string (B307) |
| 3 | Medium | CWE-502 | A08 | src/cache.py:45 | pickle.loads() on data from network socket (B301) |
| 4 | Low | CWE-703 | A07 | src/config.py:8 | assert used for input validation (B101) |

### Recommendations
1. Replace subprocess shell calls with list-based arguments (Finding #1)
2. Replace eval() with ast.literal_eval() or a safe parser (Finding #2)
3. Use json.loads() instead of pickle for untrusted data (Finding #3)

Without Bandit (Fallback Mode)

User prompt: > "Check this Python code for security issues"

Expected output (abbreviated):

## Python Security Review (Manual Fallback)

> Note: This is a limited review. Install Bandit for comprehensive scanning.

Scanned 8 .py files

### Findings (2 total: 0 Critical, 1 High, 1 Medium)

| # | Severity | CWE | OWASP | Location | Issue |
|---|----------|-----|-------|----------|-------|
| 1 | High | CWE-78 | A03 | scripts/run.py:19 | subprocess.call() with shell=True and string formatting |
| 2 | Medium | CWE-259 | A07 | config/settings.py:5 | Hardcoded password: DB_PASSWORD = "admin123" |

### Recommendations
1. Use subprocess.run() with a list of arguments instead of shell=True (Finding #1)
2. Move credentials to environment variables or a secrets manager (Finding #2)

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: kalshamsi
• Source: kalshamsi/claude-security-skills
• License: MIT

Install and usage instructions live in the source repository linked above.