# T1133 - External Remote Services

## SOC Recommendation
Investigate External Remote Services activity in the context of Persistence/Initial Access: 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 |
|---|---|---|
| Session Termination | Evict | Use Session Termination to remove the adversary's foothold once this technique is confirmed. |

## 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 |
|---|---|---|---|
| Revoke session immediately | Medium | No | Yes |
| Block IP in Conditional Access Named Locations | Medium | No | Yes |
| Reset password and force MFA re-enrolment | Medium | No | Yes |
| Audit all actions taken during the Tor session | Low | No | Yes |

## KQL
```kql
let HighRiskPorts = dynamic([3389,20,23,110,143,3306,8080,1433,9200,9300,25,445,135,21,1434,4333,5432,5500,5601,22,3000,5000,8088,8888]);
AWSSecurityHubFindings
| where RecordState == "ACTIVE" and ComplianceStatus == "FAILED"
| where tostring(AwsSecurityFindingGeneratorId) == "security-control/EC2.19"
      or tostring(ComplianceSecurityControlId) == "EC2.19"
| mv-expand Resource = Resources
| where tostring(Resource.Type) == "AwsEc2SecurityGroup"
| extend SGDetails = Resource.Details.AwsEc2SecurityGroup
| extend IpPermissions = SGDetails.IpPermissions
| mv-expand Perm = IpPermissions
| where toint(Perm.FromPort) in (HighRiskPorts)
| mv-expand Range = Perm.IpRanges
| where tostring(Range.CidrIp) in ("0.0.0.0/0", "::/0")
| summarize TimeGenerated = max(TimeGenerated), OpenHighRiskPorts = make_set(tostring(Perm.FromPort))
    by AwsAccountId, AwsRegion, AwsSecurityFindingTitle, AwsSecurityFindingDescription,
       AwsSecurityFindingId, ComplianceSecurityControlId, SecurityGroupId = tostring(SGDetails.GroupId), SecurityGroupARN = tostring(Resource.Id)
| extend OpenHighRiskPorts = strcat_array(OpenHighRiskPorts, ", ")
```
```kql
ApacheHTTPServer
| where HttpRequestMethod =~ "GET"
| where UrlOriginal has_all ("/cgi-bin/", "/%2e%2e/")
| where HttpStatusCode == "200" 
| extend UrlCustomEntity = UrlOriginal
```
```kql
let cmd_list = dynamic(['whoami', 'dpkg', 'useradd', 'sudo', 'cat']);
ApacheHTTPServer
| where UrlOriginal has_any (cmd_list)
| extend UrlCustomEntity = UrlOriginal
```

## Escalation Criteria
- External Remote Services 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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