🛡️ Sentinel: [HIGH] Fix SSRF via HTTP Redirects

[seonghobae]

🚨 Severity: HIGH
💡 Vulnerability: Server-Side Request Forgery (SSRF) bypass due to urllib.request.urlopen blindly following HTTP redirects. An attacker could provide an allowed external URL (like https://github.com/) that subsequently returns a 301 or 302 redirect to an internal, private, or loopback IP (like http://127.0.0.1/).
🎯 Impact: An attacker could bypass the _is_safe_url checks on the initial request and successfully make requests to internal services, potentially interacting with sensitive infrastructure.
🔧 Fix:

• Created a custom SafeRedirectHandler (inheriting from urllib.request.HTTPRedirectHandler) in both appguardrail_core/controlplane.py and scanner/cli/appguardrail.py.
• Overrode the redirect_request method to explicitly call _is_safe_url on any new redirect URL, raising urllib.error.URLError if the URL resolves to an unsafe address.
• Changed the invocations of urllib.request.urlopen to use urllib.request.build_opener(SafeRedirectHandler()).open().
  ✅ Verification:
• Modified unit tests in test_controlplane.py to mock build_opener instead of urlopen.
• Added a specific regression test test_safe_redirect_blocks_unsafe_url in tests/test_ssrf_protection.py to verify that URLError is raised when the redirect attempts to resolve to loopback (127.0.0.1) or link-local (169.254.169.254). All tests pass perfectly.

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PR created automatically by Jules for task 16119752968268062907 started by @seonghobae

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📥 Commits

Reviewing files that changed from the base of the PR and between 906c362 and 75a5a93.

📒 Files selected for processing (5)

• .jules/sentinel.md
• appguardrail_core/controlplane.py
• scanner/cli/appguardrail.py
• tests/test_controlplane.py
• tests/test_ssrf_protection.py

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