Description

Adds generic HTTP Request Smuggling detection to Artemis using custom Nuclei templates, as requested by @kazet in #303

Changes

• NEW: [http-request-smuggling-clte.yaml] — CL.TE variant detection
• NEW: [http-request-smuggling-tecl.yaml] — TE.CL variant detection
• NEW: [http-request-smuggling-tete.yaml] — TE.TE obfuscation detection (3 probes: duplicate header, trailing space, invalid value)
• MODIFIED: [pl_PL.py] — Added Polish translations for all 3 templates

No Python code changes required — templates are auto-loaded via the existing nuclei_templates_custom/ directory mechanism.

Detection Method

All templates use Nuclei's unsafe: true mode with the rawhttp library to send malformed HTTP requests that exploit disagreements in how front-end and back-end servers parse request boundaries. The "GPOST" probe technique is used: if a smuggled G prefix gets prepended to a subsequent POST request, the server returns an error for the unrecognized GPOST method — confirming the vulnerability.

False Positive Mitigation

This was the primary design concern, following @kazet's guidance that simply checking for HTTP/1.1 would produce too many false positives.

• Active verification, not passive detection — only triggers on concrete evidence of request boundary disagreement
• matchers-condition: and — requires BOTH a status code anomaly (400/405/501) AND specific error text (e.g., "Unrecognized method GPOST")
• Severity: medium — appropriate for CERT team triage

Testing

Tested all 3 templates against PortSwigger Web Security Academy labs:

Negative testing: Ran templates against non-vulnerable servers (single-server setups) — zero false positives.

Related Issue

Closes #303