Eresus python audit

Python Security Audit

Purpose

Perform a comprehensive, depth-first security audit of Python codebases. This skill provides the complete knowledge of Bandit's 50+ security checks, organized by category and severity, plus framework-specific patterns for Django, Flask, FastAPI, and emerging ML/AI attack surfaces.

Use view_file and grep_search exclusively. No terminal commands.

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Audit Workflow

Phase 1: Reconnaissance

1. Identify the Python framework in use (Django, Flask, FastAPI, Tornado, aiohttp, raw stdlib)
2. Check requirements.txt / pyproject.toml / Pipfile for dangerous dependencies
3. Map entry points: URL routes, CLI commands, message consumers, scheduled tasks
4. Identify configuration files and secrets management approach

Phase 2: Systematic Check — By Category

Work through each category below. For each check, use grep_search to find all instances, then view_file to trace the data flow and confirm exploitability.

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B1xx — Miscellaneous Checks

ID	Name	Severity	What to Search
B101	assert_used	Low	assert statements used for security checks (removed with -O flag)
B102	exec_used	Medium	exec() calls — trace if input is user-controlled
B103	set_bad_file_permissions	Medium	os.chmod() with overly permissive modes (0o777, 0o666)
B104	hardcoded_bind_all_interfaces	Medium	Binding to 0.0.0.0 — exposes service on all interfaces
B105	hardcoded_password_string	Low	Strings assigned to variables named password, secret, key, token
B106	hardcoded_password_funcarg	Low	Password-like strings passed as function arguments
B107	hardcoded_password_default	Low	Default parameter values containing password-like strings
B108	hardcoded_tmp_directory	Low	Hardcoded /tmp paths — race conditions, symlink attacks
B109	password_config_option_not_marked_secret	Low	Config options with password/secret that aren't marked as sensitive
B110	try_except_pass	Low	except: pass — silently swallowing errors including security exceptions
B111	execute_with_run_as_root_equals_true	Medium	Functions called with run_as_root=True
B112	try_except_continue	Low	except: continue — same problem as B110
B113	request_without_timeout	Medium	requests.get/post() without timeout= parameter — DoS via hang

Audit Depth for B1xx

• B101: Check if assert guards authentication or authorization. If so, HIGH severity.
• B102: Trace exec() input — if user-controlled, escalate to CRITICAL (RCE).
• B105/106/107: Check if the hardcoded credentials are for production systems or test fixtures.
• B113: Check all HTTP client calls (requests, httpx, urllib3, aiohttp) for timeout.

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B2xx — Application/Framework Misconfiguration

ID	Name	Severity	What to Search
B201	flask_debug_true	High	app.run(debug=True) — enables Werkzeug debugger (RCE)
B202	tarfile_unsafe_members	High	tarfile.extractall() without filter= — path traversal via tar

Audit Depth for B2xx

• B201: Check if debug=True is conditional on environment or always on. Check for WERKZEUG_DEBUG_PIN.
• B202: Any tarfile.open() + extractall() from user-uploaded files = CRITICAL path traversal.

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B3xx — Dangerous Function Calls (Blacklists)

ID	Name	Severity	What to Search
B324	hashlib	Medium	Use of md5(), sha1() for security-sensitive operations (password hashing, integrity)

Extended B3xx Checks (Eresus additions)

• hashlib.md5() / hashlib.sha1() for password storage → escalate to HIGH
• Use of random module instead of secrets for security tokens → HIGH
• string.Template with user input → potential template injection

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B5xx — Cryptography

ID	Name	Severity	What to Search
B501	request_with_no_cert_validation	High	requests.get(url, verify=False) — TLS downgrade
B502	ssl_with_bad_version	High	ssl.SSLContext(ssl.PROTOCOL_SSLv2) or SSLv3
B503	ssl_with_bad_defaults	Medium	SSLContext with insecure default protocol
B504	ssl_with_no_version	Medium	SSLContext created without explicit protocol
B505	weak_cryptographic_key	High	RSA < 2048 bits, DSA < 2048 bits, EC < 224 bits
B506	yaml_load	Medium	yaml.load() without Loader=SafeLoader — deserialization RCE
B507	ssh_no_host_key_verification	High	Paramiko set_missing_host_key_policy(AutoAddPolicy)
B508	snmp_insecure_version	Medium	SNMPv1/v2 without authentication
B509	snmp_weak_cryptography	Medium	SNMPv3 with weak crypto

Audit Depth for B5xx

• B501: Check if cert pinning is used. If verify=False is in production code → CRITICAL.
• B506: This is a deserialization sink. If input comes from HTTP/file upload → CRITICAL RCE.

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B6xx — Injection

ID	Name	Severity	What to Search
B601	paramiko_calls	Medium	Paramiko SSH command execution — trace if command is user-controlled
B602	subprocess_popen_with_shell_equals_true	High	subprocess.Popen(cmd, shell=True) — command injection
B603	subprocess_without_shell_equals_true	Low	subprocess.Popen(cmd) without shell — still check input
B604	any_other_function_with_shell_equals_true	Medium	Any function with shell=True parameter
B605	start_process_with_a_shell	High	os.system(), os.popen() — command injection
B606	start_process_with_no_shell	Low	os.execl(), os.execve() — still trace input
B607	start_process_with_partial_path	Low	Process started without full path — PATH hijacking
B608	hardcoded_sql_expressions	Medium	SQL strings built with + or % or f-strings
B609	linux_commands_wildcard_injection	High	Commands with * glob — wildcard injection (tar, chown, etc.)
B610	django_extra_used	Medium	Django QuerySet.extra() — raw SQL injection
B611	django_rawsql_used	Medium	Django RawSQL() — raw SQL injection
B612	logging_config_insecure_listen	Medium	logging.config.listen() — arbitrary code execution
B613	trojansource	High	Unicode bidirectional control characters — trojan source attack
B614	pytorch_load	High	torch.load() — uses pickle internally, RCE if untrusted
B615	huggingface_unsafe_download	High	HuggingFace model downloads without safety checks

Audit Depth for B6xx

• B602/B605: Trace the command string backwards. If ANY part is user-controlled → CRITICAL RCE.
• B608: Check if the SQL is parameterized elsewhere. Raw f-string SQL = HIGH SQLi.
• B609: tar cf archive.tar * in /tmp with user-created files → argument injection.
• B614: torch.load() from user-uploaded model file → CRITICAL RCE via pickle.
• B615: ML model supply chain attack — check if trust_remote_code=True.

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B7xx — XSS / Template Injection

ID	Name	Severity	What to Search
B701	jinja2_autoescape_false	High	jinja2.Environment(autoescape=False) — stored/reflected XSS
B702	use_of_mako_templates	Medium	Mako templates — no auto-escaping by default
B703	django_mark_safe	Medium	mark_safe(user_input) — bypasses Django auto-escaping
B704	markupsafe_markup_xss	Medium	Markup(user_input) — bypasses escaping

Audit Depth for B7xx

• B701: If autoescape=False and template renders user input → CRITICAL XSS.
• B703: Trace what data is passed to mark_safe(). If user-controlled → HIGH XSS.

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Framework-Specific Deep Checks

Django

• Check ALLOWED_HOSTS configuration (empty = open redirect)
• Check CSRF_COOKIE_HTTPONLY, SESSION_COOKIE_SECURE, SECURE_BROWSER_XSS_FILTER
• Check for @csrf_exempt decorators on sensitive views
• Check DEBUG = True in production settings
• Check SECRET_KEY hardcoded or in version control
• Check MIDDLEWARE ordering (SecurityMiddleware should be first)
• Check AUTH_PASSWORD_VALIDATORS configuration

Flask

• Check SECRET_KEY generation (must be cryptographically random)
• Check app.run(debug=True) in production
• Check for @app.before_request authentication enforcement
• Check session cookie configuration (SESSION_COOKIE_SECURE, SESSION_COOKIE_HTTPONLY)
• Check file upload handling (werkzeug.utils.secure_filename)

FastAPI

• Check for missing input validation (Body(), Query(), Path() without constraints)
• Check CORS configuration (allow_origins=["*"])
• Check authentication dependency injection (missing Depends())
• Check FileResponse / StreamingResponse path traversal
• Check OAuth2 implementation (token validation, scope enforcement)

ML/AI Attack Surface

• torch.load() — pickle-based, RCE from untrusted models
• transformers.pipeline(trust_remote_code=True) — arbitrary code execution
• pickle.loads() in model serialization pipelines
• Prompt injection in LLM-based applications
• Model poisoning via untrusted training data

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Severity Matrix

Confidence \ Severity	LOW	MEDIUM	HIGH
HIGH	Info	Medium	Critical
MEDIUM	Low	Medium	High
LOW	Info	Low	Medium

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Report Format

For each finding, report:

### [B-ID]: [Check Name]

**Severity**: [LOW/MEDIUM/HIGH/CRITICAL]
**Confidence**: [LOW/MEDIUM/HIGH]
**File**: [path]:[line]

**Vulnerable Code**:
[show the code]

**Data Flow**:
[source] → [intermediaries] → [sink]

**Impact**: [what an attacker achieves]
**Remediation**: [specific fix with code example]
**Bandit Reference**: B[xxx]

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Tooling Constraints

Use ONLY:

• view_file — read source code
• grep_search — find patterns across the codebase

Do NOT use any terminal commands.