undermybelt Performing Purple Team Exercise
When to Use
Use this skill when:
- SOC teams need to validate that detection rules actually fire for the threats they target
- Red team assessments produced findings that need translation into detection improvements
- New detection tools or SIEM migrations require validation of detection coverage
- Analyst training requires hands-on experience with real attack techniques and SIEM responses
- Quarterly or semi-annual detection validation cycles are scheduled
Do not use for unannounced red team engagements — purple team exercises require explicit coordination between offensive and defensive teams with real-time collaboration.
Prerequisites
- Red team capability: internal team or contracted purple team operator
- Attack simulation tools: Atomic Red Team, MITRE Caldera, or C2 framework (authorized)
- SIEM access for real-time alert monitoring during exercise
- ATT&CK-mapped detection rule inventory with expected alert names
- Isolated test environment or approved production scope with change management approval
- Communication channel (Slack/Teams) for real-time red-blue coordination
Workflow
Step 1: Define Exercise Scope and Objectives
Document exercise parameters:
purple_team_exercise:
exercise_id: PT-2024-Q1
date: 2024-03-20
duration: 8 hours (09:00-17:00 UTC)
scope:
environment: Production (Finance VLAN, 10.0.5.0/24)
systems_in_scope:
- WORKSTATION-TEST01 (10.0.5.100) — Test endpoint
- DC-TEST (10.0.5.200) — Test domain controller
- FILESERVER-TEST (10.0.5.201) — Test file server
systems_excluded:
- All production domain controllers
- Customer-facing systems
objectives:
- Validate 15 detection rules mapped to FIN7 TTPs
- Test SOC analyst response to real attack indicators
- Identify detection gaps for credential access and lateral movement
- Measure detection latency for each technique
threat_scenario: FIN7 campaign targeting financial data via spearphishing
authorization: Approved by CISO, Change Request CR-2024-0567
communication: #purple-team-2024q1 Slack channel
Step 2: Build ATT&CK-Mapped Test Plan
Create technique-by-technique test matrix:
| # | ATT&CK ID | Technique | Test Tool | Expected Detection | Blue Team Metric |
|---|---|---|---|---|---|
| 1 | T1566.001 | Spearphishing Attachment | Manual email | Email gateway alert | Detection Y/N, latency |
| 2 | T1204.002 | User Execution | Macro document | Sysmon process creation | Detection Y/N, latency |
| 3 | T1059.001 | PowerShell | Atomic RT #1-3 | PowerShell execution alert | Detection Y/N, latency |
| 4 | T1053.005 | Scheduled Task | Atomic RT | Scheduled task creation alert | Detection Y/N, latency |
| 5 | T1547.001 | Registry Run Keys | Atomic RT | Registry modification alert | Detection Y/N, latency |
| 6 | T1003.001 | LSASS Memory | Mimikatz | Credential dumping alert | Detection Y/N, latency |
| 7 | T1550.002 | Pass-the-Hash | Mimikatz | NTLM anomaly detection | Detection Y/N, latency |
| 8 | T1021.002 | SMB/PsExec | PsExec | PsExec service creation alert | Detection Y/N, latency |
| 9 | T1047 | WMI | wmic /node | WMI remote execution alert | Detection Y/N, latency |
| 10 | T1021.001 | RDP | xfreerdp | RDP lateral movement alert | Detection Y/N, latency |
| 11 | T1071.001 | Web C2 | Cobalt Strike | C2 beacon detection | Detection Y/N, latency |
| 12 | T1041 | Exfiltration C2 | Rclone | Data exfiltration alert | Detection Y/N, latency |
| 13 | T1490 | Inhibit Recovery | vssadmin | Shadow copy deletion alert | Detection Y/N, latency |
| 14 | T1486 | Data Encrypted | Test encryption | Mass encryption detection | Detection Y/N, latency |
| 15 | T1070.001 | Clear Logs | wevtutil | Log clearing detection | Detection Y/N, latency |
Step 3: Execute Red Team Techniques
Run each technique with Atomic Red Team (or manual execution):
# Install Atomic Red Team
IEX (IWR 'https://raw.githubusercontent.com/redcanaryco/invoke-atomicredteam/master/install-atomicredteam.ps1' -UseBasicParsing)
Install-AtomicRedTeam -getAtomics
# Test 1: T1059.001 — PowerShell Execution
Write-Host "[$(Get-Date -Format 'HH:mm:ss')] Executing T1059.001 - PowerShell"
Invoke-AtomicTest T1059.001 -TestNumbers 1
# Notify blue team: "T1059.001 executed at $(Get-Date)"
# Test 2: T1053.005 — Scheduled Task Creation
Write-Host "[$(Get-Date -Format 'HH:mm:ss')] Executing T1053.005 - Scheduled Task"
Invoke-AtomicTest T1053.005 -TestNumbers 1
# Test 3: T1547.001 — Registry Run Key
Write-Host "[$(Get-Date -Format 'HH:mm:ss')] Executing T1547.001 - Registry Persistence"
Invoke-AtomicTest T1547.001 -TestNumbers 1,2
# Test 4: T1003.001 — Credential Dumping
Write-Host "[$(Get-Date -Format 'HH:mm:ss')] Executing T1003.001 - LSASS Access"
Invoke-AtomicTest T1003.001 -TestNumbers 1,2
# Test 5: T1490 — Shadow Copy Deletion
Write-Host "[$(Get-Date -Format 'HH:mm:ss')] Executing T1490 - Inhibit Recovery"
Invoke-AtomicTest T1490 -TestNumbers 1
# Cleanup after each test
Invoke-AtomicTest T1059.001 -TestNumbers 1 -Cleanup
Invoke-AtomicTest T1053.005 -TestNumbers 1 -Cleanup
Invoke-AtomicTest T1547.001 -TestNumbers 1,2 -Cleanup
Step 4: Monitor Blue Team Detection in Real-Time
Blue team monitors SIEM during execution:
--- Real-time purple team monitoring dashboard
index=notable earliest=-1h
| where Computer IN ("WORKSTATION-TEST01", "DC-TEST", "FILESERVER-TEST")
OR src IN ("10.0.5.100", "10.0.5.200", "10.0.5.201")
| eval detection_latency = _time - orig_time
| eval latency_seconds = round(detection_latency, 0)
| sort _time
| table _time, rule_name, urgency, src, dest, user, latency_seconds
--- Check specific technique detection
index=sysmon Computer="WORKSTATION-TEST01" earliest=-15m
(EventCode=1 OR EventCode=3 OR EventCode=10 OR EventCode=11 OR EventCode=13)
| sort _time
| table _time, EventCode, Image, CommandLine, TargetFilename, TargetObject
Record results in real-time:
exercise_results = {
"exercise_id": "PT-2024-Q1",
"results": [
{
"technique": "T1059.001",
"name": "PowerShell Execution",
"execution_time": "09:15:00",
"detected": True,
"alert_name": "Suspicious PowerShell Encoded Command",
"detection_time": "09:15:47",
"latency_seconds": 47,
"notes": "Detected via Sysmon EventCode 1 with encoded command pattern"
},
{
"technique": "T1003.001",
"name": "LSASS Memory Access",
"execution_time": "10:30:00",
"detected": False,
"alert_name": None,
"detection_time": None,
"latency_seconds": None,
"notes": "GAP: No detection rule for LSASS access. Sysmon EventCode 10 present but no correlation rule."
}
]
}
Step 5: Collaborative Gap Remediation
For each gap, the blue team builds detection rules immediately:
--- Gap: T1003.001 — No LSASS access detection
--- Build rule during exercise
index=sysmon EventCode=10 TargetImage="*\\lsass.exe"
GrantedAccess IN ("0x1010", "0x1038", "0x1fffff", "0x40")
NOT SourceImage IN ("*\\svchost.exe", "*\\csrss.exe", "*\\MsMpEng.exe")
| stats count by Computer, SourceImage, SourceUser, GrantedAccess
| where count > 0
After building, re-test:
Red Team: "Re-executing T1003.001 at 11:45"
Blue Team: "Confirmed — alert 'LSASS Memory Access Detected' fired at 11:45:32 (32s latency)"
Result: GAP CLOSED
Step 6: Generate Exercise Report
def generate_purple_team_report(results):
total = len(results["results"])
detected = sum(1 for r in results["results"] if r["detected"])
gaps = sum(1 for r in results["results"] if not r["detected"])
avg_latency = sum(r["latency_seconds"] for r in results["results"]
if r["latency_seconds"]) / max(detected, 1)
report = f"""
PURPLE TEAM EXERCISE REPORT — {results['exercise_id']}
{'=' * 60}
SUMMARY:
Techniques Tested: {total}
Detected: {detected} ({detected/total*100:.0f}%)
Gaps Identified: {gaps} ({gaps/total*100:.0f}%)
Avg Detection Latency: {avg_latency:.0f} seconds
DETAILED RESULTS:
"""
for r in results["results"]:
status = "DETECTED" if r["detected"] else "GAP"
latency = f"{r['latency_seconds']}s" if r["latency_seconds"] else "N/A"
report += f" [{status}] {r['technique']} — {r['name']} (Latency: {latency})\n"
if not r["detected"]:
report += f" Action: {r['notes']}\n"
return report
Key Concepts
| Term | Definition |
|---|---|
| Purple Team | Collaborative exercise where red (offensive) and blue (defensive) teams work together to validate and improve detection |
| Adversary Emulation | Structured simulation of specific threat actor TTPs for testing defensive capabilities |
| Detection Validation | Process of confirming that detection rules fire correctly when the targeted technique is executed |
| Detection Latency | Time between technique execution and SIEM alert generation — measured during purple team exercises |
| Gap Remediation | Immediate creation or tuning of detection rules for techniques that were not detected during testing |
| Atomic Red Team | Open-source library of small, focused tests for individual ATT&CK techniques |
Tools & Systems
- Atomic Red Team: Open-source attack test library from Red Canary for technique-by-technique validation
- MITRE Caldera: Automated adversary emulation platform supporting ATT&CK-mapped attack chains
- Vectr: Purple team management platform for tracking exercise results and detection coverage improvements
- Prelude Operator: Adversary emulation tool supporting automated multi-step attack scenarios
- AttackIQ: Breach and Attack Simulation (BAS) platform for continuous detection validation
Common Scenarios
- Quarterly Validation: Test top 20 detection rules against ATT&CK techniques to ensure continued effectiveness
- New Tool Validation: After deploying new EDR, validate detection coverage against baseline techniques
- Analyst Training: Junior analysts observe real attacks in real-time with expert guidance on SIEM investigation
- Post-Incident Validation: After a real incident, emulate the attack chain to verify detection improvements
- Compliance Evidence: Document detection validation results for SOC 2, ISO 27001, or PCI DSS audits
Output Format
PURPLE TEAM EXERCISE REPORT — PT-2024-Q1
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Date: 2024-03-20 (09:00-17:00 UTC)
Scenario: FIN7 Financial Sector Campaign
Scope: Finance VLAN (10.0.5.0/24)
RESULTS:
Techniques Tested: 15
Detected: 11 (73%)
Gaps Identified: 4 (27%)
Gaps Remediated Same Day: 3
Avg Detection Latency: 38 seconds
DETAILED RESULTS:
[PASS] T1566.001 Spearphishing Attachment — 12s latency
[PASS] T1204.002 User Execution (Macro) — 8s latency
[PASS] T1059.001 PowerShell Execution — 47s latency
[PASS] T1053.005 Scheduled Task — 23s latency
[PASS] T1547.001 Registry Run Keys — 31s latency
[FAIL] T1003.001 LSASS Memory Access — REMEDIATED during exercise
[FAIL] T1550.002 Pass-the-Hash — REMEDIATED during exercise
[PASS] T1021.002 PsExec — 15s latency
[PASS] T1047 WMI Remote Execution — 42s latency
[PASS] T1021.001 RDP Lateral Movement — 28s latency
[FAIL] T1071.001 Web C2 Beaconing — REMEDIATED during exercise
[PASS] T1041 Exfiltration over C2 — 67s latency
[PASS] T1490 Shadow Copy Deletion — 5s latency
[FAIL] T1486 Data Encryption for Impact — OPEN — requires endpoint telemetry
[PASS] T1070.001 Event Log Clearing — 11s latency
POST-EXERCISE COVERAGE: 93% (14/15) — up from 73% at start
REMAINING GAP: T1486 requires EDR file monitoring enhancement