# T1615 - Group Policy Discovery

## SOC Recommendation
Investigate Group Policy Discovery activity in the context of Discovery: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.

## D3FEND Mappings
| D3FEND Technique | Relationship | Practical SOC Action |
|---|---|---|
| Restore Configuration | Restore | Use Restore Configuration to recover affected systems or data after containment. |
| Configuration Inventory | Model | Use Configuration Inventory to establish a baseline that makes this technique's deviations easier to spot. |

## Investigation Steps
1. Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.
2. Check Sentinel analytics rules and incidents correlated with this technique.
3. Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource.

## Evidence to Collect
- Host or resource affected
- Account or identity involved
- Timestamp of the activity
- Related process, file, or network artifact
- Any preceding or follow-on alerts

## Response Actions
| Action | Risk | Automation Safe | Approval Required |
|---|---|---|---|
| Contain the affected host or account | Medium | No | Yes |
| Collect and preserve evidence | Low | Yes | No |

## KQL
```kql
let regexEmpire = tostring(toscalar(externaldata(cmdlets:string)[@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/EmpireCommandString.txt"] with (format="txt")));
(union isfuzzy=true
 (SecurityEvent
| where EventID == 4688
//consider filtering on filename if perf issues occur
//where FileName in~ ("powershell.exe","powershell_ise.exe","pwsh.exe")
| where not(ParentProcessName has_any ('gc_worker.exe', 'gc_service.exe'))
| where CommandLine has "-encodedCommand"
| parse kind=regex flags=i CommandLine with * "-EncodedCommand " encodedCommand
| extend encodedCommand = iff(encodedCommand has " ", tostring(split(encodedCommand, " ")[0]), encodedCommand)
// Note: currently the base64_decode_tostring function is limited to supporting UTF8
| extend decodedCommand = translate('\0','', base64_decode_tostring(substring(encodedCommand, 0, strlen(encodedCommand) -  (strlen(encodedCommand) %8)))), encodedCommand, CommandLine , strlen(encodedCommand)
| extend EfectiveCommand = iff(isnotempty(encodedCommand), decodedCommand, CommandLine)
| where EfectiveCommand matches regex regexEmpire
| project timestamp = TimeGenerated, Computer, SubjectUserName, SubjectDomainName, FileName = Process, EfectiveCommand, decodedCommand, encodedCommand, CommandLine, ParentProcessName
| extend HostName = split(Computer, '.', 0)[0], DnsDomain = strcat_array(array_slice(split(Computer, '.'), 1, -1), '.')
),
(WindowsEvent
| where EventID == 4688
| where EventData has_any ("-encodedCommand", "powershell.exe","powershell_ise.exe","pwsh.exe")
| where not(EventData has_any ('gc_worker.exe', 'gc_service.exe'))
//consider filtering on filename if perf issues occur
//extend NewProcessName = tostring(EventData.NewProcessName)
//extend Process=tostring(split(NewProcessName, '\\')[-1])
//FileName = Process
//where FileName in~ ("powershell.exe","powershell_ise.exe","pwsh.exe")
| extend ParentProcessName = tostring(EventData.ParentProcessName)
| where not(ParentProcessName has_any ('gc_worker.exe', 'gc_service.exe'))
| extend CommandLine = tostring(EventData.CommandLine)
| where CommandLine has "-encodedCommand"
| parse kind=regex flags=i CommandLine with * "-EncodedCommand " encodedCommand
| extend encodedCommand = iff(encodedCommand has " ", tostring(split(encodedCommand, " ")[0]), encodedCommand)
// Note: currently the base64_decode_tostring function is limited to supporting UTF8
| extend decodedCommand = translate('\0','', base64_decode_tostring(substring(encodedCommand, 0, strlen(encodedCommand) -  (strlen(encodedCommand) %8)))), encodedCommand, CommandLine , strlen(encodedCommand)
| extend EfectiveCommand = iff(isnotempty(encodedCommand), decodedCommand, CommandLine)
| where EfectiveCommand matches regex regexEmpire
| extend SubjectUserName = tostring(EventData.SubjectUserName)
| extend SubjectDomainName = tostring(EventData.SubjectDomainName)
| extend NewProcessName = tostring(EventData.NewProcessName)
| extend Process=tostring(split(NewProcessName, '\\')[-1])
| project timestamp = TimeGenerated, Computer, SubjectUserName, SubjectDomainName, FileName = Process, EfectiveCommand, decodedCommand, encodedCommand, CommandLine, ParentProcessName
| extend HostName = split(Computer, '.', 0)[0], DnsDomain = strcat_array(array_slice(split(Computer, '.'), 1, -1), '.')
))
```

## Escalation Criteria
- Group Policy Discovery activity observed on a privileged account or critical system.
- Activity follows or precedes other suspicious behaviour in the same investigation.
- Automated triage cannot confidently rule out malicious intent.

## False Positive Considerations
- Legitimate administrative or maintenance activity matching this pattern.
- Approved security testing or red team exercise.
- Known benign software producing similar telemetry.

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