Threat Model:tna

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name: threat-model:tna description: Analyze a PR for TNA (Two-Node Arbiter) security threats with STRIDE/DFD analysis, MITRE ATT&CK and OWASP mapping disable-model-invocation: true allowed-tools: Read, Grep, Glob, Write, Edit, Bash, WebFetch argument-hint: "<PR-number | GitHub-URL | repo PR-number>"

TNA PR Threat Analysis

Analyze a pull request for security threats against the TNA (Two-Node Arbiter) topology, map to MITRE ATT&CK, and generate a formal report.

This skill focuses on TNA-specific DFD elements, trust boundaries, and code paths. For TNF analysis, use /threat-model:tnf.

Reference Files

Bundled with this skill:

• dfd-elements-tna.md — TNA DFD element catalog (TNA-P1, TNA-P3–P5, TNA-DS5–DS6, TNA-TB1–TB3)

Shared references (in $PLUGIN_DIR/references/):

• mitre-reference.md — MITRE ATT&CK lookup with DFD element mappings
• owasp-reference.md — OWASP Top 10:2025 mapping with DFD element cross-references
• mitre-findings-template.md — Template for cumulative findings tracker

Discovered at runtime from the workspace:

• $THREAT_MODEL_DIR/TNA-THREAT-MODEL.md — TNA formal threat model with DFD and per-element STRIDE analysis
• $FINDINGS_FILE — TNA findings tracker (created from template on first use)

Workspace Discovery

Before starting analysis, discover the workspace layout.

Discovery Steps

1. Find workspace root: Walk upward from $PWD until a directory containing repos/ is found. If no parent qualifies, fall back to checking whether the current git repo sits inside a repos/ directory:

   d="$PWD"
   while [ "$d" != "/" ]; do
     if [ -d "$d/repos" ]; then
       echo "$d"
       break
     fi
     d="$(dirname "$d")"
   done
   if [ "$d" = "/" ]; then
     repo_root="$(git rev-parse --show-toplevel 2>/dev/null || true)"
     if [ -n "$repo_root" ] && [ "$(basename "$(dirname "$repo_root")")" = "repos" ]; then
       echo "$(dirname "$(dirname "$repo_root")")"
     fi
   fi
   

2. Set workspace paths: Once the workspace root (WORKSPACE) is found:

   • Repos directory: $WORKSPACE/repos/
   • Threat model: Look for TNA-THREAT-MODEL.md in:
     • $WORKSPACE/repos/two-node-toolbox/docs/
     • $WORKSPACE/docs/
     • The current directory
   • Report output: If $REPORT_DIR is already set in the environment, use it directly. Otherwise, write reports to the same directory where the threat model is found. If not found, write to $WORKSPACE/reports/ (create if needed).
   • Findings tracker: $WORKSPACE/.claude/skills/threat-model/mitre-findings-tna.md — initialized from $PLUGIN_DIR/references/mitre-findings-template.md on first use.

3. Validate workspace: Warn the user if:

   • No repos/ directory is found
   • Required repos for the target PR are not cloned locally
   • Threat model reference file is not found (analysis can still proceed, but DFD cross-referencing will be skipped)

Path Variables Reference

Variable	Description	Example
$WORKSPACE	Root directory containing repos/	/home/user/Projects/tna-dev-env
$REPOS	Repos directory	$WORKSPACE/repos
$THREAT_MODEL_DIR	Directory containing formal threat model	$REPOS/two-node-toolbox/docs
$REPORT_DIR	Directory for generated reports	Same as $THREAT_MODEL_DIR or $WORKSPACE/reports
$FINDINGS_FILE	TNA findings tracker	$WORKSPACE/.claude/skills/threat-model/mitre-findings-tna.md

Findings File

Each threat-model skill writes to its own findings file (mitre-findings-tnf.md, mitre-findings-tna.md, mitre-findings-sno.md, mitre-findings-lvms.md), so no file locking is required during concurrent execution.

Append protocol (use in step 12):

FINDINGS_FILE="$WORKSPACE/.claude/skills/threat-model/mitre-findings-tna.md"

mkdir -p "$(dirname "$FINDINGS_FILE")"
cp -n "RESOLVED_TEMPLATE_PATH" "$FINDINGS_FILE"

cat >> "$FINDINGS_FILE" <<'FINDINGS_BLOCK'

## TNA — REPO PR #NUMBER (YYYY-MM-DD)

| Technique ID | Technique Name | Finding | Severity | Status | Notes |
|--------------|----------------|---------|----------|--------|-------|
| T#### | Name | VULN-# | Severity | Open | Description |

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FINDINGS_BLOCK

Substitute RESOLVED_TEMPLATE_PATH with the absolute path to $PLUGIN_DIR/references/mitre-findings-template.md (resolved from this skill's directory). Fill in REPO, NUMBER, YYYY-MM-DD, and the table rows from the current analysis.

Input Formats

Option 1: PR Number Only

/threat-model:tna 1437

Detects the repository from the current working directory. Must be inside a repo under $REPOS/<repo>/.

Option 2: GitHub PR URL

/threat-model:tna https://github.com/openshift/cluster-etcd-operator/pull/1437

Extracts org, repo, and PR number from the URL automatically.

Option 3: Explicit repo and PR

/threat-model:tna cluster-etcd-operator 1437

Specify repo name and PR number explicitly.

Parsing Logic

1. If input is a URL (contains github.com):

   • Extract org/repo/PR from: https://github.com/<org>/<repo>/pull/<PR>

2. If input is a single number:

   • Detect repo from current directory path
   • Look for pattern repos/<repo-name>/ in the working directory
   • Use the repo's configured remote to determine the org

3. If input is <repo> <number>:

   • Use provided repo name
   • Look up org from the repository mapping table

Repository Mapping

Repo	GitHub Org
assisted-service	openshift
cluster-etcd-operator	openshift
machine-config-operator	openshift
installer	openshift
cluster-baremetal-operator	openshift
origin	openshift
dev-scripts	openshift-metal3
release	openshift
enhancements	openshift
openshift-docs	openshift

Instructions

1. Discover workspace using the Workspace Discovery steps above
2. Parse input to determine org, repo, and PR number
3. Fetch PR details using gh pr view <PR> --repo <org>/<repo> or WebFetch
4. Get changed files with gh pr diff <PR> --repo <org>/<repo> or WebFetch
5. Run ShellCheck on any shell scripts in the changed files (see Automated Scanner section)
6. Analyze all changes for security-relevant patterns (see Security Patterns)
7. Map to DFD elements — identify which DFD elements are affected using the TNA mapping table below and dfd-elements-tna.md
8. Apply per-element STRIDE to affected elements and cross-reference against $THREAT_MODEL_DIR/TNA-THREAT-MODEL.md (if found)
9. Combine findings from ShellCheck + AI analysis + DFD/STRIDE analysis
10. Map findings to MITRE ATT&CK techniques (see $PLUGIN_DIR/references/mitre-reference.md)
11. Generate report at $REPORT_DIR/
12. Append findings to tracker — follow the Append Protocol to write a findings block to $FINDINGS_FILE

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Automated Scanner: ShellCheck

ShellCheck is available in RHEL/Fedora repos (dnf install ShellCheck) - no external downloads required.

Installation Check

command -v shellcheck >/dev/null && echo "shellcheck: installed" || echo "shellcheck: NOT installed (run: dnf install ShellCheck)"

Running ShellCheck

shellcheck -f json <script-file>
shellcheck -S warning <script-file>
shellcheck -s bash <script-file>

Security-Relevant ShellCheck Codes

Code	Severity	Security Relevance	MITRE
SC2086	Warning	Unquoted variable - command injection risk	T1059
SC2091	Warning	Command in $() used as condition - injection	T1059
SC2046	Warning	Unquoted command substitution	T1059
SC2012	Info	Parsing ls output - can be exploited	T1059
SC2029	Warning	ssh command with unescaped variables	T1059
SC2087	Warning	Unquoted heredoc - variable expansion	T1059
SC2155	Warning	Declare/assign separately to avoid masking errors	-
SC2164	Warning	cd without without error-exit guard - path traversal risk	T1083

Include in Report

Add ShellCheck results under Automated Scanner Results:

## Automated Scanner Results

### ShellCheck

**Tool**: ShellCheck (from RHEL repos)
**Version**: X.X.X

| Code | Severity | File | Line | Message |
|------|----------|------|------|---------|
| SC2086 | warning | script.sh | 42 | Double quote to prevent globbing and word splitting |

If ShellCheck is not installed, note: Not installed. Install with: dnf install ShellCheck If no shell scripts in PR, note: No shell scripts in this PR - skipped.

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Optional External Scanners

The following scanners provide additional coverage but require external downloads. Use at your own discretion.

Tool	Source	Risks	Mitigations
Semgrep	pip/GitHub	Fetches rules from semgrep.dev; may send telemetry	Use --offline mode with local rules
Gitleaks	GitHub releases	Binary from external source	Verify checksums; use container image
gosec	GitHub/go install	Binary from external source	Verify checksums; audit source

command -v semgrep >/dev/null && echo "semgrep: installed" || echo "semgrep: not installed (external)"
command -v gitleaks >/dev/null && echo "gitleaks: installed" || echo "gitleaks: not installed (external)"
command -v gosec >/dev/null && echo "gosec: installed" || echo "gosec: not installed (external)"

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Security Patterns to Detect

Category	Patterns	MITRE	Severity
Command Injection	shell exec, os.system, subprocess, fmt.Sprintf with shell	T1059	Critical
Credentials	hardcoded secrets, API keys, tokens, passwords in code	T1552	Critical
Privilege Escalation	setuid, capabilities, privileged containers, sudo, nsenter	T1548	High
Authentication	auth bypass, weak validation, token handling flaws	T1078	High
Crypto Weakness	weak algorithms, hardcoded keys, disabled TLS verify	T1573	High
Path Traversal	unsanitized file paths, symlink attacks	T1083	Medium
Container Escape	host mounts, hostPID, hostNetwork, privileged mode	T1611	Critical
Logging Exposure	sensitive data in logs, credential printing	T1005	Medium
SSRF/Network	unvalidated URLs, exposed internal endpoints	T1046	Medium
Deserialization	unsafe unmarshal, pickle, yaml.load	T1059	High

TNA DFD Element Mapping

See dfd-elements-tna.md for the full element catalog.

Code Path to DFD Element

Code Path Pattern	DFD Element	STRIDE Focus
installer/pkg/asset/machines/arbiter*	TNA-P1 (Installer)	T, D
installer/pkg/asset/ignition/machine/arbiter*	TNA-P1, TNA-DS6	T, I
installer/pkg/types/installconfig.go (IsArbiterEnabled)	TNA-P1	T, D
installer/pkg/types/validation/installconfig.go (arbiter)	TNA-P1	T
assisted-service/internal/common/common.go (arbiter)	TNA-P1	T
assisted-service/internal/cluster/validator.go (arbiter role)	TNA-P1	S, T
machine-config-operator/manifests/arbiter*	TNA-P3 (MCO)	T, D
machine-config-operator/templates/arbiter/	TNA-P3	T, E
cluster-etcd-operator/pkg/operator/ceohelpers/control_plane_topology.go	TNA-P4 (CEO)	T, D
cluster-etcd-operator/pkg/operator/ceohelpers/multiselector_lister.go	TNA-P4	T, D
cluster-etcd-operator/pkg/operator/configobservation/*replicas*	TNA-P4	T, D
origin/test/extended/two_node/arbiter_topology.go	Test	-
origin/test/extended/two_node/tna_recovery.go	Test	-

Trust Boundary Crossings

When a PR modifies code that crosses a trust boundary, apply additional scrutiny:

Boundary Crossing	Code Indicators	Key Threats
TNA-TB1->TNA-TB2 (Admin -> K8s API)	install-config, oc commands	S (admin impersonation), T (config tampering)
TNA-TB2 internal (MCO -> kubelet)	arbiter MCP, kubelet config, taint	T (taint removal), D (misconfiguration)
TNA-TB2->TNA-TB3 (K8s API -> Worker)	CSR approval, ignition endpoint	S (rogue CSR), E (lateral movement)

Per-Element STRIDE for PR Analysis

For each affected DFD element, ask these questions:

Processes (all 6 STRIDE categories):

• S: Can the process be impersonated? Are auth checks adequate?
• T: Can inputs/outputs be modified? Is data validated?
• R: Are actions auditable? Are logs adequate and redacted?
• I: Does it handle secrets? Are they protected in transit/at rest?
• D: Can it be crashed or blocked? What happens on failure?
• E: Does it run with minimal privilege? Can it be abused for escalation?

Data Stores (T, I, D):

• T: Can stored data be modified by unauthorized parties?
• I: Is sensitive data encrypted? Who can read it?
• D: Can the store be corrupted or deleted?

Data Flows (T, I, D):

• T: Can data in transit be modified? Is integrity verified?
• I: Is the channel encrypted? Are credentials visible?
• D: Can the flow be interrupted or flooded?

External Entities (S, R):

• S: Can the entity be impersonated? Is authentication enforced?
• R: Can the entity deny having performed an action? Are interactions logged?

Cross-Referencing the Threat Model

After identifying per-element threats, check against $THREAT_MODEL_DIR/TNA-THREAT-MODEL.md:

1. Search for relevant PE-<element>-* IDs in the Per-Element STRIDE Analysis section
2. If a PR introduces a new threat not covered by existing PE-* entries, flag it as a gap
3. If a PR mitigates an existing PE-* threat, note it as a positive finding
4. If a PR worsens an existing PE-* threat, flag with elevated severity

If the formal threat model file is not found, skip cross-referencing and note this in the report.

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Report Output

Use report templates from $PLUGIN_DIR/references/report-templates.md. Set <topology> to TNA when filling in the templates.