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docs(audit): update FINDING-002 to informational (by design)

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Firewall OUTPUT DROP policy confirmed as intentional for immutable
system security model:
- Zero traffic leakage (no DNS poisoning, NTP spoofing, C2 exfil)
- Immutable system with no in-place updates
- WireGuard endpoint loaded via USB disk
- Time synchronized from host/hypervisor

Updated risk summary: 1 HIGH (Secure Boot), 4 MEDIUM, 3 LOW, 2 INFO

Remaining findings (001, 005, 006, 007, 008) to be addressed by
software team per audit recommendations.

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Assisted-by: GLM-4 via Crush <crush@charm.land>
This commit is contained in:
Charles N Wyble
2026-02-20 10:35:42 -05:00
parent c8b004cf3e
commit 09b4f12026
2 changed files with 41 additions and 37 deletions
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docs/audit/2026-02-20/SUMMARY.md
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@@ -30,10 +30,10 @@ KNEL-Football is a hardened Debian 13 Linux distribution designed as a **secure
| Severity | Count | Key Areas |
|----------|-------|-----------|
| Critical | 0 | - |
| High | 2 | Secure Boot keys, Firewall output |
| High | 1 | Secure Boot keys |
| Medium | 4 | Docker privileged, USB automount, KDF config, Supply chain |
| Low | 3 | Test gaps, Documentation, Input validation |
| Info | 1 | Package management |
| Info | 2 | Firewall (by design), Package management |
---
@@ -45,14 +45,19 @@ Keys generated at build time without HSM or secure storage. An attacker with bui
**Impact**: Complete chain of trust compromise
**Effort**: Medium (requires key management infrastructure)
### 2. Firewall Output Chain Blocks Essential Services (HIGH)
Default DROP policy on OUTPUT chain prevents DNS resolution, NTP synchronization, and system updates.
**Impact**: System cannot function properly (DNS, time sync, updates)
**Effort**: Low (add explicit allow rules)
---
## Design Decisions Confirmed
### Firewall Output Policy (By Design)
The strict OUTPUT DROP policy was confirmed as **intentional** for an immutable system:
- Zero traffic leakage (no DNS poisoning, NTP spoofing, C2 exfiltration vectors)
- Immutable system with no in-place updates (CVEs handled by ISO regeneration)
- WireGuard endpoint loaded via USB disk (wg0.conf)
- Time synchronized from host/hypervisor
**Assessment**: Defensible security posture for an air-gapped access terminal.
## Positive Security Observations
1. **Strong SDLC Enforcement** - Pre-commit hooks enforce TDD, linting, and coverage
@@ -67,9 +72,8 @@ Default DROP policy on OUTPUT chain prevents DNS resolution, NTP synchronization
## Recommendations Priority
### Must Fix Before Release
1. Fix firewall OUTPUT chain to allow DNS/NTP/updates
2. Disable USB automount (conflicts with security model)
3. Verify Argon2id KDF is actually used in LUKS
1. Disable USB automount (conflicts with security model)
2. Verify Argon2id KDF is actually used in LUKS
### Short-term (30 days)
1. Implement Secure Boot key management with HSM or air-gapped storage
@@ -92,7 +96,7 @@ Default DROP policy on OUTPUT chain prevents DNS resolution, NTP synchronization
| NIST SP 800-53 AC-19 | ⚠️ Issue | USB automount |
| NIST SP 800-111 | ✅ Pass | LUKS2 encryption |
| CIS Benchmark 6.x | ✅ Pass | Comprehensive audit logging |
| FedRAMP SC-7 | ⚠️ Issue | Firewall output policy |
| FedRAMP SC-7 | ✅ Pass | Strict output policy (by design) |
---
@@ -105,9 +109,9 @@ Default DROP policy on OUTPUT chain prevents DNS resolution, NTP synchronization
## Conclusion
KNEL-Football demonstrates **mature security architecture** with strong foundations. The project is **suitable for production with remediation** of the two HIGH findings. The SDLC practices are exemplary and should be maintained.
KNEL-Football demonstrates **mature security architecture** with strong foundations. The project is **suitable for production with remediation** of the HIGH finding. The SDLC practices are exemplary and should be maintained.
**Recommendation**: Address firewall and Secure Boot key issues before release. The remaining findings can be addressed post-release with documented timelines.
**Recommendation**: Address Secure Boot key management before release. The firewall output policy is confirmed as intentional design for an immutable system.
---