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Detection rules › Kusto

Zscaler - Unexpected update operation

Status
available
Severity
medium
Time window
1h
Source
github.com/Azure/Azure-Sentinel

'Detects unexpected version of update operation.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1133 External Remote Services, T1190 Exploit Public-Facing Application

Rule body kusto

id: 672e2846-4226-11ec-81d3-0242ac130003
name: Zscaler - Unexpected update operation
description: |
  'Detects unexpected version of update operation.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CustomLogsAma
    datatypes:
      - ZPA_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  ZPAEvent
  | where isnotempty(AuditOperationType)
  | extend ExpectedVersion1 = extract(@'(expectedVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 2, AuditOldValue)
  | extend ExpectedVersion2 = extract(@'(expectedVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 3, AuditOldValue)
  | extend NewVersion1 = extract(@'("currentVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 2, AuditNewValue)
  | extend NewVersion2 = extract(@'("currentVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 3, AuditNewValue)
  | extend Comparision1 = iff(tolong(ExpectedVersion2) > tolong(NewVersion2), 'Unexpected version', 'Expected version')
  | extend VersionCheck = iff(tolong(ExpectedVersion1) > tolong(NewVersion1), 'Unexpected version', Comparision1)
  | project-away ExpectedVersion1, ExpectedVersion2, NewVersion1, NewVersion2, Comparision1
  | extend ProcessCustomEntity = AuditOperationType
entityMappings:
  - entityType: Process
    fieldMappings:
      - identifier: ProcessId
        columnName: ProcessCustomEntity
version: 1.0.2
kind: Scheduled

Stages and Predicates

Stage 1: source

ZPAEvent

Stage 2: where

| where isnotempty(AuditOperationType)

Stage 3: extend (6 consecutive steps)

| extend ExpectedVersion1 = extract(@'(expectedVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 2, AuditOldValue)
| extend ExpectedVersion2 = extract(@'(expectedVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 3, AuditOldValue)
| extend NewVersion1 = extract(@'("currentVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 2, AuditNewValue)
| extend NewVersion2 = extract(@'("currentVersion":")([0-9]+)\.([0-9]+\.[0-9]+)', 3, AuditNewValue)
| extend Comparision1 = iff(tolong(ExpectedVersion2) > tolong(NewVersion2), 'Unexpected version', 'Expected version')
| extend VersionCheck = iff(tolong(ExpectedVersion1) > tolong(NewVersion1), 'Unexpected version', Comparision1)

Stage 4: project-away

| project-away ExpectedVersion1, ExpectedVersion2, NewVersion1, NewVersion2, Comparision1

Stage 5: extend

| extend ProcessCustomEntity = AuditOperationType

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
AuditOperationTypeis_not_null
  • (no value, null check)

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
VersionCheckextend
ProcessCustomEntityextend