Office Policy Tampering

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Id	fbd72eb8-087e-466b-bd54-1ca6ea08c6d3
Rulename	Office Policy Tampering
Description	Identifies if any tampering is done to either auditlog, ATP Safelink, SafeAttachment, AntiPhish or Dlp policy. An adversary may use this technique to evade detection or avoid other policy based defenses. References: https://docs.microsoft.com/powershell/module/exchange/advanced-threat-protection/remove-antiphishrule?view=exchange-ps.
Severity	Medium
Tactics	Persistence DefenseEvasion
Techniques	T1098 T1562
Required data connectors	Office365
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/office_policytampering.yaml
Version	2.0.3
Arm template	fbd72eb8-087e-466b-bd54-1ca6ea08c6d3.json

KQL

let opList = OfficeActivity 
| summarize by Operation
//| where Operation startswith "Remove-" or Operation startswith "Disable-"
| where Operation has_any ("Remove", "Disable")
| where Operation contains "AntiPhish" or Operation contains "SafeAttachment" or Operation contains "SafeLinks" or Operation contains "Dlp" or Operation contains "Audit"
| summarize make_set(Operation, 500);
OfficeActivity
// Only admin or global-admin can disable/remove policy
| where RecordType =~ "ExchangeAdmin"
| where UserType in~ ("Admin","DcAdmin")
// Pass in interesting Operation list
| where Operation in~ (opList)
| extend ClientIPOnly = case( 
ClientIP has ".", tostring(split(ClientIP,":")[0]), 
ClientIP has "[", tostring(trim_start(@'[[]',tostring(split(ClientIP,"]")[0]))),
ClientIP
)  
| extend Port = case(
ClientIP has ".", (split(ClientIP,":")[1]),
ClientIP has "[", tostring(split(ClientIP,"]:")[1]),
ClientIP
)
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), OperationCount = count() by Operation, UserType, UserId, ClientIP = ClientIPOnly, Port, ResultStatus, Parameters
| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])

YAML

status: Available
queryFrequency: 1d
id: fbd72eb8-087e-466b-bd54-1ca6ea08c6d3
tactics:
- Persistence
- DefenseEvasion
entityMappings:
- fieldMappings:
  - columnName: UserId
    identifier: FullName
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
  entityType: Account
- fieldMappings:
  - columnName: ClientIP
    identifier: Address
  entityType: IP
requiredDataConnectors:
- connectorId: Office365
  dataTypes:
  - OfficeActivity (Exchange)
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/office_policytampering.yaml
version: 2.0.3
query: |
  let opList = OfficeActivity 
  | summarize by Operation
  //| where Operation startswith "Remove-" or Operation startswith "Disable-"
  | where Operation has_any ("Remove", "Disable")
  | where Operation contains "AntiPhish" or Operation contains "SafeAttachment" or Operation contains "SafeLinks" or Operation contains "Dlp" or Operation contains "Audit"
  | summarize make_set(Operation, 500);
  OfficeActivity
  // Only admin or global-admin can disable/remove policy
  | where RecordType =~ "ExchangeAdmin"
  | where UserType in~ ("Admin","DcAdmin")
  // Pass in interesting Operation list
  | where Operation in~ (opList)
  | extend ClientIPOnly = case( 
  ClientIP has ".", tostring(split(ClientIP,":")[0]), 
  ClientIP has "[", tostring(trim_start(@'[[]',tostring(split(ClientIP,"]")[0]))),
  ClientIP
  )  
  | extend Port = case(
  ClientIP has ".", (split(ClientIP,":")[1]),
  ClientIP has "[", tostring(split(ClientIP,"]:")[1]),
  ClientIP
  )
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), OperationCount = count() by Operation, UserType, UserId, ClientIP = ClientIPOnly, Port, ResultStatus, Parameters
  | extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])  
description: |
  'Identifies if any tampering is done to either auditlog, ATP Safelink, SafeAttachment, AntiPhish or Dlp policy. 
  An adversary may use this technique to evade detection or avoid other policy based defenses.
  References: https://docs.microsoft.com/powershell/module/exchange/advanced-threat-protection/remove-antiphishrule?view=exchange-ps.'  
relevantTechniques:
- T1098
- T1562
triggerThreshold: 0
queryPeriod: 1d
triggerOperator: gt
name: Office Policy Tampering
severity: Medium
kind: Scheduled

ARM