feat(guard): runtime DNS SSRF bypass detection — WRD-RES-EXFIL-DNS-SSRF (#11)#73
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…FIL-DNS-SSRF, #11) Closes the bypass where WRD-RES-EXFIL-IP-LITERAL could not fire because the tools/call result contained a DNS hostname (e.g. 169.254.169.254.nip.io) rather than a raw IP literal. New rule WRD-RES-EXFIL-DNS-SSRF: guard resolves URL hostnames from result text at runtime via concurrent.futures.ThreadPoolExecutor (bounded 1 s, fail-open) and error-replaces when any resolved IP falls in SSRF_NETWORKS (link-local, loopback, RFC1918, IPv6 ULA/link-local/loopback). Opt-out via --no-block-exfil-dns-ssrf or --no-block-deterministic. Offline inspect command unchanged. Files: res_dns.py (new), res_catalog.py, result_inspection.py, guard_loop.py, guard_result.py, cli_guard.py, tests/test_res_dns.py (19 new), test_guard_posture.py (+4). All 530 tests pass. Closes DSE-58.
…workflow The repo transferred to DataScience-EngineeringExperts but the --certificate-identity flag still referenced the personal account (ernestprovo23). Fulcio mints a cert whose SAN reflects the actual org, so the exact-string equality check in sigstore 4.3.0 failed. Updated both the verify and negative-proof steps. Fixes Sigstore sign+verify (live) failure on PR #73.
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…-57) (#74) * feat(guard): runtime DNS resolution SSRF bypass detection (WRD-RES-EXFIL-DNS-SSRF, #11) Closes the bypass where WRD-RES-EXFIL-IP-LITERAL could not fire because the tools/call result contained a DNS hostname (e.g. 169.254.169.254.nip.io) rather than a raw IP literal. New rule WRD-RES-EXFIL-DNS-SSRF: guard resolves URL hostnames from result text at runtime via concurrent.futures.ThreadPoolExecutor (bounded 1 s, fail-open) and error-replaces when any resolved IP falls in SSRF_NETWORKS (link-local, loopback, RFC1918, IPv6 ULA/link-local/loopback). Opt-out via --no-block-exfil-dns-ssrf or --no-block-deterministic. Offline inspect command unchanged. Files: res_dns.py (new), res_catalog.py, result_inspection.py, guard_loop.py, guard_result.py, cli_guard.py, tests/test_res_dns.py (19 new), test_guard_posture.py (+4). All 530 tests pass. Closes DSE-58. * fix(ci): correct Sigstore certificate-identity org in integrity-gate workflow The repo transferred to DataScience-EngineeringExperts but the --certificate-identity flag still referenced the personal account (ernestprovo23). Fulcio mints a cert whose SAN reflects the actual org, so the exact-string equality check in sigstore 4.3.0 failed. Updated both the verify and negative-proof steps. Fixes Sigstore sign+verify (live) failure on PR #73. * feat(transport): add HTTP/SSE transport support to pin and check (DSE-57) Add streamable_http_client path to capture.py (_capture_http_async, capture_surface_http, capture_surface_http_sync). Extend CapturedSurface and ServerIdentity with optional url field (backward-compat, defaults None). Update _server_identity() to hash the URL when set. Route check_core run_check_full() and cli pin/check commands through HTTP capture when --url is provided; mutually exclusive with positional server-cmd. 6 new tests (async + sync, mocked transport, error paths).
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Summary
WRD-RES-EXFIL-DNS-SSRF: the guard now DNS-resolves URL hostnames fromtools/callresults at runtime and error-replaces when any resolved IP falls inSSRF_NETWORKSWRD-RES-EXFIL-IP-LITERALmissed destinations whose hostname (e.g.169.254.169.254.nip.io) resolves to a private/metadata IP rather than appearing as a raw literalHow it works
inspect_result()(pure, no IO), the guard extracts non-IP-literal URL hostnames from each result block viares_dns.extract_dns_candidates()res_dns.resolve_ssrf_hits()resolves them in aThreadPoolExecutorbounded by 1 second across all hosts — fail-open (anyOSError→ no hit)SSRF_NETWORKS(same table as the raw-IP-literal rule)WRD-RES-EXFIL-DNS-SSRF, block tier, error-replace (same posture asWRD-RES-EXFIL-DOMAIN)Opt-out
Files changed
src/mcp_warden/res_dns.pysrc/mcp_warden/res_catalog.pyinspect_exfil_dns_ssrf()src/mcp_warden/result_inspection.pyBLOCK_RULESsrc/mcp_warden/guard_loop.pyGuardConfig.no_block_exfil_dns_ssrf+_DET_OPTOUTentrysrc/mcp_warden/guard_result.pyinspect_result;_dns_ssrf_findings(); add toerror_rulessrc/mcp_warden/cli_guard.py--no-block-exfil-dns-ssrfflag wiredtests/test_res_dns.pytests/test_guard_posture.pyCHANGELOG.md[Unreleased]entry; remove DNS from out-of-scope listTest plan
uv run pytest tests/test_res_dns.py→ 19/19 passuv run pytest tests/test_guard_posture.py→ 14/14 passOSErrorfrom DNS → no findings, frame forwardedWRD-RES-EXFIL-IP-LITERAL)--no-block-exfil-dns-ssrfand--no-block-deterministicboth demote the rule🤖 Generated with Claude Code
https://claude.ai/code/session_01Btjz6CMgR5U9EZmzgCsaG5