🛡️ Sentinel: [HIGH] Fix SSRF vulnerability in website analysis and document processing

[criptogus]

🚨 Severity: HIGH
💡 Vulnerability: Server-Side Request Forgery (SSRF) bypass via redirects. The validateWebUrl function checked the initial URL, but axios followed redirects automatically, potentially exposing private internal services (e.g. metadata services) if the target server redirected to a private IP.
🎯 Impact: Attackers could access internal services, read metadata, or perform port scanning on the internal network by supplying a malicious URL that redirects to internal IPs.
🔧 Fix:

• Enhanced backend/src/utils/ssrf-filter.ts to include getSafeHttpAgent and getSafeHttpsAgent.
• These agents use a custom DNS lookup that validates the IP address against private ranges before connection, preventing DNS rebinding and ensuring redirects are also checked.
• Updated WebsiteAnalysisService and DocumentSourceProcessorService to use these safe agents.
  ✅ Verification:
• Added backend/src/utils/ssrf-filter.test.ts to verify IP blocking logic.
• Ran tests with npx jest.

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PR created automatically by Jules for task 18376192908279637184 started by @criptogus

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