Agent skill

performing-purple-team-exercise

Performs purple team exercises by coordinating red team adversary emulation with blue team detection validation using MITRE ATT&CK-mapped attack scenarios, real-time detection testing, and collaborative gap remediation. Use when SOC teams need to validate detection capabilities, improve analyst skills, and close detection gaps through structured offensive-defensive collaboration.

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SKILL.md

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:

yaml
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):

powershell
# 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:

spl
--- 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:

python
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:

spl
--- 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

python
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

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