// Create, deploy, and execute custom Atomic Red Team tests (T9999.XXX series) for detection validation. Covers YAML authoring, Ansible deployment, and manual alternatives.
| name | Custom Atomics Deployment |
| description | Create, deploy, and execute custom Atomic Red Team tests (T9999.XXX series) for detection validation. Covers YAML authoring, Ansible deployment, and manual alternatives. |
When no standard Atomic Red Team test covers your detection scenario, create a custom atomic using the T9999.XXX numbering scheme. This avoids collisions with upstream technique IDs while giving you full control over the test payload.
Required environment variables:
| Variable | Description | Example |
|---|---|---|
$ATOMICS_PATH | Path to atomic-red-team atomics directory | /opt/atomic-red-team/atomics |
$CUSTOM_ATOMICS_PATH | Path to your custom atomics repo/directory | /opt/custom-atomics |
$ATTACK_RANGE_PATH | Path to Attack Range (if using AR for deployment) | /opt/attack-range |
$ATTACK_RANGE_VENV | Attack Range Python venv | /opt/attack-range/.venv |
$ANSIBLE_INVENTORY | Path to Ansible inventory file | /etc/ansible/hosts |
Target placeholders:
<TARGET_IP> — IP address of the test endpoint<TARGET_NAME> — Hostname of the test endpoint (e.g., ar-win-1)| Range | Purpose | Example |
|---|---|---|
| T9999.001–T9999.099 | Windows endpoint tests | T9999.001: Encoded PowerShell download cradle |
| T9999.100–T9999.199 | Linux endpoint tests | T9999.100: Cron persistence via echo |
| T9999.200–T9999.299 | Cloud / SaaS tests | T9999.200: AWS IAM key rotation abuse |
| T9999.300–T9999.399 | Network / protocol tests | T9999.300: DNS TXT record exfiltration |
| T9999.400–T9999.499 | macOS tests | T9999.400: LaunchAgent persistence |
$CUSTOM_ATOMICS_PATH/
T9999.001/
T9999.001.yaml
src/
payload.ps1 (optional supporting files)
T9999.002/
T9999.002.yaml
attack_technique: T9999.001
display_name: "Custom - Suspicious Encoded PowerShell Download"
atomic_tests:
- name: "PowerShell download cradle with Net.WebClient and encoding"
auto_generated_guid: <generate-a-uuid>
description: |
Simulates an encoded PowerShell download cradle using Net.WebClient.
Maps to T1059.001 (PowerShell) + T1105 (Ingress Tool Transfer).
Designed to trigger detections for encoded command execution.
supported_platforms:
- windows
input_arguments:
target_url:
description: URL to download from
type: url
default: "http://127.0.0.1:8080/test.txt"
dependency_executor_name: powershell
dependencies:
- description: "PowerShell must be available"
prereq_command: "Get-Command powershell.exe"
get_prereq_command: "echo 'PowerShell not found'"
executor:
command: |
$encoded = [Convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes("(New-Object Net.WebClient).DownloadString('#{target_url}')"))
powershell.exe -EncodedCommand $encoded
cleanup_command: |
echo "No cleanup required"
name: powershell
elevation_required: false
auto_generated_guid — Generate with uuidgen or any UUID toolinput_arguments — Makes tests reusable across environmentsdependencies — Prerequisite checks prevent confusing failurescleanup_command — Even if it's just a no-op, document itAnsible provides idempotent, repeatable deployment to one or many targets.
Deploy custom atomic to Windows target:
ansible <TARGET_NAME> -m win_copy \
-a "src=$CUSTOM_ATOMICS_PATH/T9999.001/ dest=C:\\AtomicRedTeam\\atomics\\T9999.001\\" \
--extra-vars "ansible_host=<TARGET_IP>"
Deploy to Linux target:
ansible <TARGET_NAME> -m copy \
-a "src=$CUSTOM_ATOMICS_PATH/T9999.100/ dest=/opt/atomic-red-team/atomics/T9999.100/ mode=0755" \
--extra-vars "ansible_host=<TARGET_IP>"
Deploy all custom atomics at once:
ansible <TARGET_NAME> -m win_copy \
-a "src=$CUSTOM_ATOMICS_PATH/ dest=C:\\AtomicRedTeam\\atomics\\" \
--extra-vars "ansible_host=<TARGET_IP>"
For one-off deployments without Ansible:
# Linux target
scp -r "$CUSTOM_ATOMICS_PATH/T9999.100" user@<TARGET_IP>:/opt/atomic-red-team/atomics/
# Windows target (via PowerShell remoting)
$session = New-PSSession -ComputerName <TARGET_IP> -Credential (Get-Credential)
Copy-Item -Path "$env:CUSTOM_ATOMICS_PATH\T9999.001" -Destination "C:\AtomicRedTeam\atomics\" -ToSession $session -Recurse
cd "$ATTACK_RANGE_PATH"
source "$ATTACK_RANGE_VENV/bin/activate"
# Use AR's simulate with custom atomics path
python attack_range.py simulate -t T9999.001 --target <TARGET_NAME>
Note: Attack Range may need configuration to recognize custom atomics paths.
| Tool | Use Case | Notes |
|---|---|---|
| Ansible | Multi-target, repeatable | Best for lab environments |
| SCP/WinRM | Single target, quick | Fine for one-off testing |
| Terraform provisioner | Part of lab build | Deploy atomics during infra setup |
| Salt/Puppet/Chef | Existing config management | Use if already in your stack |
| Git clone on target | Self-service | Target pulls from atomics repo |
# Import module (if not already loaded)
Import-Module "C:\AtomicRedTeam\invoke-atomicredteam\Invoke-AtomicRedTeam.psd1"
# List custom atomic tests
Invoke-AtomicTest T9999.001 -ShowDetailsBrief
# Run prerequisites
Invoke-AtomicTest T9999.001 -TestNumbers 1 -GetPrereqs
# Execute
Invoke-AtomicTest T9999.001 -TestNumbers 1
# Cleanup
Invoke-AtomicTest T9999.001 -TestNumbers 1 -Cleanup
If using the Go-based atomic runner (goart):
./goart run T9999.100
Or execute manually based on the YAML's command field.
# Windows
ansible <TARGET_NAME> -m win_shell \
-a "Import-Module C:\\AtomicRedTeam\\invoke-atomicredteam\\Invoke-AtomicRedTeam.psd1; Invoke-AtomicTest T9999.001 -TestNumbers 1" \
--extra-vars "ansible_host=<TARGET_IP>"
# Linux
ansible <TARGET_NAME> -m shell \
-a "/opt/goart/goart run T9999.100" \
--extra-vars "ansible_host=<TARGET_IP>"
After deploying and executing a custom atomic:
yamllint T9999.XXX.yaml)auto_generated_guid is present and uniqueInvoke-AtomicTest -ShowDetailsBrief lists the test correctly| Problem | Likely Cause | Fix |
|---|---|---|
| Atomic not found on target | Path mismatch | Verify atomics folder matches Invoke-AtomicRedTeam config |
| YAML parse error | Indentation or special characters | Run yamllint; escape special chars in commands |
| Test fails with "prereq not met" | Missing dependency | Run -GetPrereqs or install manually |
| No telemetry in SIEM | Forwarder issue or wrong sourcetype | Check forwarder status, verify index/sourcetype |
| Detection doesn't fire | Field mismatch or time window | Widen search window; check field names |
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