feat(aws): add transfer_server_pqc_ssh_kex_enabled check

[pedrooot]

Context

"Harvest now, decrypt later" attacks capture encrypted traffic today to decrypt it once a cryptographically relevant quantum computer exists. Since 2025, AWS Transfer Family ships security policies that add a hybrid post-quantum SSH key exchange (ML-KEM combined with classical ECDHE), but Prowler had no signal for whether a server actually uses one.

Description

Adds the transfer_server_pqc_ssh_kex_enabled check. It evaluates every AWS Transfer Family server's SecurityPolicyName against a configurable allowlist of post-quantum policies (transfer_pqc_ssh_allowed_policies, defaults: TransferSecurityPolicy-2025-03, TransferSecurityPolicy-FIPS-2025-03, TransferSecurityPolicy-AS2Restricted-2025-07). A server passes when it uses one of these policies and fails otherwise. The deprecated *-PQ-SSH-Experimental-2023-04 policies are intentionally excluded. The transfer service is extended to expose SecurityPolicyName. Severity: low.

Steps to review

1. Check implementation: prowler/providers/aws/services/transfer/transfer_server_pqc_ssh_kex_enabled/
2. Service change exposing SecurityPolicyName: prowler/providers/aws/services/transfer/transfer_service.py
3. Run the tests: poetry run pytest tests/providers/aws/services/transfer/transfer_server_pqc_ssh_kex_enabled/ tests/providers/aws/services/transfer/transfer_service_test.py -v
4. Optionally run against a real environment: prowler aws --check transfer_server_pqc_ssh_kex_enabled

Checklist

Community Checklist

• This feature/issue is listed in here or roadmap.prowler.com
• Is it assigned to me, if not, request it via the issue/feature in here or Prowler Community Slack

• Review if the code is being covered by tests.
• Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings
• Review if backport is needed.
• Review if is needed to change the Readme.md
• Ensure new entries are added to CHANGELOG.md, if applicable.

SDK/CLI

• Are there new checks included in this PR? Yes
  • No new permissions needed: transfer:ListServers/transfer:DescribeServer are already covered by the AWS managed SecurityAudit/ViewOnlyAccess policies.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[github-actions]

Compliance Mapping Review

This PR adds new checks. Please verify that they have been mapped to the relevant compliance framework requirements.

New checks already mapped in this PR

• transfer_server_pqc_ssh_kex_enabled (aws): aws_well_architected_framework_security_pillar_aws, ccc_aws, csa_ccm_4.0_aws, ens_rd2022_aws, fedramp_moderate_revision_4_aws, ffiec_aws, gxp_21_cfr_part_11_aws, iso27001_2013_aws, kisa_isms_p_2023_aws, kisa_isms_p_2023_korean_aws, nist_800_171_revision_2_aws, nist_800_53_revision_5_aws, rbi_cyber_security_framework_aws, secnumcloud_3.2_aws

Use the no-compliance-check label to skip this check.

[github-actions]

✅ All necessary CHANGELOG.md files have been updated.

[github-actions]

✅ Conflict Markers Resolved

All conflict markers have been successfully resolved in this pull request.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 2.78%. Comparing base (7d03bc5) to head (d4f3a73).
⚠️ Report is 13 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (7d03bc5) and HEAD (d4f3a73). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (7d03bc5)	HEAD (d4f3a73)
api	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #11315       +/-   ##
===========================================
- Coverage   93.97%    2.78%   -91.19%     
===========================================
  Files         237      858      +621     
  Lines       34829    25137     -9692     
===========================================
- Hits        32729      701    -32028     
- Misses       2100    24436    +22336     

Flag	Coverage Δ
api	?
prowler-py3.10-aws	2.30% <100.00%> (?)
prowler-py3.10-config	2.78% <100.00%> (?)
prowler-py3.11-aws	2.30% <100.00%> (?)
prowler-py3.11-config	2.78% <100.00%> (?)
prowler-py3.12-aws	2.30% <100.00%> (?)
prowler-py3.12-config	2.78% <100.00%> (?)

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Components	Coverage Δ
prowler	2.78% <100.00%> (∅)
api	∅ <ø> (∅)

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[github-actions]

🔒 Container Security Scan

Image: prowler:5e98019
Last scan: 2026-05-21 22:34:26 UTC

📊 Vulnerability Summary

Severity	Count
🔴 Critical	6
Total	6

5 package(s) affected

⚠️ Action Required

Critical severity vulnerabilities detected. These should be addressed before merging:

• Review the detailed scan results
• Update affected packages to patched versions
• Consider using a different base image if updates are unavailable

---

📋 Resources:

• Download full report (see artifacts)
• View in Security tab
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