# T1559 - Inter-Process Communication

## SOC Recommendation
Investigate Inter-Process Communication activity in the context of Execution: 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 |
|---|---|---|
| Network Traffic Analysis | Detect | Monitor for Network Traffic Analysis indicators relevant to this technique. |

## 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
// Allowlisted UPNs should likely stay empty
let AllowlistedUpns = datatable(UPN:string)['foo@bar.com', 'test@foo.com'];
// Operation Name parts that will alert
let HasAnyBlocklist = datatable(OperationNamePart:string)['Security.','Project.','AuditLog.','Extension.'];
// Distinct Operation Names that will flag
let HasExactBlocklist = datatable(OperationName:string)['Group.UpdateGroupMembership.Add','Library.ServiceConnectionExecuted','Pipelines.PipelineModified',
'Release.ReleasePipelineModified', 'Git.RefUpdatePoliciesBypassed'];
ADOAuditLogs
| where AuthenticationMechanism startswith "PAT" and (OperationName has_any (HasAnyBlocklist) or OperationName in (HasExactBlocklist))
  and ActorUPN !in (AllowlistedUpns)
| project TimeGenerated, AuthenticationMechanism, ProjectName, ActorUPN, ActorDisplayName, IpAddress, UserAgent, OperationName, Details, Data
| extend timestamp = TimeGenerated
| extend AccountName = tostring(split(ActorUPN, "@")[0]), AccountUPNSuffix = tostring(split(ActorUPN, "@")[1])
```
```kql
let timeframe=1h;
let CobaltStrikeDefaults= dynamic([@"msagent_", @"MSSE-", @"postex_", @"status_", @"mypipe-f", @"mypipe-h",@"ntsvcs_",@"scerpc_", @"mojo.5688.8052."]);
let CobaltStrikeMallable= dynamic([@"win_svc", @"ntsvcs", @"scerpc", @"status_", @"SearchTextHarvester", @"DserNamePipe",@"wkssvc_",@"scerpc_", @"spoolss_",@"CatalogChangeListener",@"fullduplex_",@"demoagent_",@"PGMessagePipe",@"MsFteWds",@"postex_ssh_",@"windows.update.manager",@"\f4c3",@"\f53f",@"halfduplex_"]);
DeviceEvents
| where Timestamp >= ago(timeframe)
| where ActionType == "NamedPipeEvent"
| extend AdditionalFields=parse_json(AdditionalFields)
| extend ThreadId=tostring(AdditionalFields.ThreadId)
| extend PipeName=tostring(AdditionalFields.PipeName)
// creating string based variants of the processIDs for matching several times later
| extend InitiatingPID=tostring(InitiatingProcessId)
| extend InitiatingParentPID=tostring(InitiatingProcessParentId)
// Begin allow-list.
// End allow-list.
| where PipeName has_any (CobaltStrikeDefaults) or
// Mojo is generated by Chrome(ium) browsers and teams and have distinct pattern including the (parent)ProcessId and ThreadId plus a random character string, CobaltStrike generates hex.
      (PipeName matches regex @"\\mojo\.\d+\.\d+\." and not(PipeName matches regex @"\\mojo\.\d+\.\d+\.\d+$" or PipeName has InitiatingPID or PipeName has InitiatingParentPID or PipeName has ThreadId)) or
// Chrome(ium) browsers sync processes have distinct pattern including the (parent)ProcessId and ThreadId plus a random character string, CobaltStrike generates hex.
      (PipeName matches regex @"\\(edge|chrome)\.sync\.\d+\.\d+\." and not(PipeName matches regex @"\\(edge|chrome|edge\.sync|chrome\.sync)\.\d+\.\d+\.\d+$" or PipeName has InitiatingPID or PipeName has InitiatingParentPID or PipeName has ThreadId)) or
// PSHost is generated by PowerShell and has a distinct pattern including the (parent)ProcessId.
      (PipeName matches regex @"\\PSHost\.\d+\." and not(PipeName matches regex @"\\PSHost\.\d+\.\d+\." or PipeName has InitiatingPID or PipeName has InitiatingParentPID)) or
// Crashpad pipes have a distinct pattern including the ProcessId and a string of upper case characters.
      (PipeName matches regex @"\\crashpad_" and not(PipeName matches regex @"\\crashpad_\d+_[A-Z]+" or PipeName has InitiatingPID or PipeName has InitiatingParentPID)) or
// Firefox pipes have a distinct pattern including the ProcessId and 1-3 digits which are sequential for each new pipe.
      (PipeName matches regex @"\\cubeb-pipe-" and not(PipeName matches regex @"\\cubeb-pipe-\d+_[0-9]{1-3}+" or PipeName has InitiatingPID)) or
// Based on a list of public mallable profiles and a suffix that is a random HEX string.
      (PipeName has_any (CobaltStrikeMallable) and PipeName matches regex @"[a-fA-F0-9]{2,10}$") or
      (PipeName matches regex @"\\pipe\\[0-9a-f]{7,10}" or PipeName matches regex @"\\pipe\\[0-9a-f]{8}")
```

## Escalation Criteria
- Inter-Process Communication 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.

Generated by SOC Response Atlas by Basyrix.