# T1531 - Account Access Removal

## SOC Recommendation
Investigate Account Access Removal activity in the context of Impact: 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 |
|---|---|---|
| Agent Authentication | Harden | Apply Agent Authentication to reduce this technique's viability before an incident occurs. |
| Account Locking | Evict | Use Account Locking to remove the adversary's foothold once this technique is confirmed. |
| User Account Permissions | Isolate | Apply User Account Permissions to contain the blast radius once this technique is observed. |
| Unlock Account | Restore | Use Unlock Account to recover affected systems or data after containment. |

## 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 |
|---|---|---|---|
| Re-enable affected accounts via break-glass / emergency admi | Low | No | Yes |
| Revoke the actor's privileges if this was an attacker action | Medium | No | Yes |
| Verify break-glass account is not compromised | Low | No | Yes |

## KQL
```kql
SAPBTPAuditLog_CL
| extend LogMessage = coalesce(tostring(Message.message), tostring(Message.data), tostring(Message))
| where LogMessage has_any ("Unauthorized access to the oData service", 
                            "All roles for providerId", 
                            "All users for providerId",
                            "were deleted successfully",
                            "were removed successfully")
| extend EventCategory = case(
    LogMessage contains "Unauthorized access", "Unauthorized Access",
    LogMessage contains "All roles" or LogMessage contains "All users", "Mass Deletion",
    "Role Tampering"
)
| extend MessageText = case(
    LogMessage contains "Unauthorized access to the oData service", "Unauthorized OData service access attempt",
    LogMessage contains "All roles for providerId" and LogMessage contains "deleted", "Mass role deletion detected",
    LogMessage contains "All users for providerId" and LogMessage contains "deleted", "Mass user deletion detected",
    LogMessage contains "assignments were removed", "User/role assignments removed",
    "Suspicious access control modification"
)
| extend ProviderId = extract(@"providerId\s+(\S+)", 1, LogMessage)
| project
    TimeGenerated,
    UserName,
    MessageText,
    EventCategory,
    ProviderId,
    Tenant,
    CloudApp = "SAP Build Work Zone Standard Edition"
| extend AccountName = split(UserName, "@")[0], UPNSuffix = split(UserName, "@")[1]
```
```kql
ValimailEnforceEvents_CL
| where EventCategory == "UserManagement"
| where EventSeverity == "High"
| where IsHighValueEvent == true
| summarize
    EventCount = count(),
    FirstSeen = min(PerformedAt),
    LastSeen = max(PerformedAt),
    AffectedUsers = make_set(Subject),
    Actions = make_set(EventType)
  by User, EventCategory
| extend
    AccountName = tostring(split(User, "@")[0]),
    AccountDomain = tostring(split(User, "@")[1])
```
```kql
JiraAudit
| where EventMessage =~ 'Permission scheme updated'
| project EventCreationTime, ObjectItemName, UserName, SrcIpAddr, ChangedValues
| extend AccountCustomEntity = UserName, IPCustomEntity = SrcIpAddr
```

## Escalation Criteria
- Account Access Removal 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.