Detection rules › Kusto

CTERA Mass Permissions Changes Detection Analytic

Status
available
Severity
high
Time window
5m
Group by
UserName
Source
github.com/Azure/Azure-Sentinel

This analytic rule detects and alerts when access denied operations generated by the CTERA Edge Filer goes over a predefined threshold

MITRE ATT&CK coverage

TacticTechniques
Privilege Escalation

Rule body

id: 90502ac9-19a2-41f0-ba81-e352de90b61b
name: CTERA Mass Permissions Changes Detection Analytic
description: 'This analytic rule detects and alerts when access denied operations generated by the CTERA Edge Filer goes over a predefined threshold'
kind: Scheduled
severity: High
status: Available
requiredDataConnectors:
  - connectorId: CTERA
    dataTypes:
      - Syslog
queryFrequency: 5m
queryPeriod: 5m
triggerOperator: GreaterThan
triggerThreshold: 5000
tactics:
  - PrivilegeEscalation
relevantTechniques:
  - T1068
query: |
  Syslog
    | where ProcessName == 'gw-audit'
    | extend
        TenantName = extract("\"vportal\":\"([^\"]*)\"", 1, SyslogMessage),
        UserName = extract("user=([^|]*)", 1, SyslogMessage),
        Operation = extract("op=([^|]*)", 1, SyslogMessage),
        EdgeFiler = extract("\"client\":\"([^\"]*)\"", 1, SyslogMessage),
        RootPath = extract("rootPath=([^|]*)", 1, SyslogMessage),
        Share = extract("share=([^|]*)", 1, SyslogMessage),
        LocalPath = extract("path=([^|]*)", 1, SyslogMessage),
        Timestamp = todatetime(extract("\"@timestamp\":\"([^\"]*)\"", 1, SyslogMessage))
    | where Operation in ('ACLAdded', 'ACLDeleted', 'ACLProtectionAdded','chown', 'setsd', 'ACLProtectionDeleted', 'ACEChanged', 'setdacl')
    | summarize Count = count() by UserName, bin(Timestamp, 5m)
    | where Count > 5000
incidentConfiguration:
    createIncident: true
    groupingConfiguration:
        enabled: false
        reopenClosedIncident: false
        lookbackDuration: PT5H
        matchingMethod: AllEntities
eventGroupingSettings:
    aggregationKind: SingleAlert
alertDetailsOverride:
    alertnameFormat: 'CTERA Batch Access Denied Detection'
    alertDescriptionFormat: >
      Detected {{Count}} denied access attempts by user {{UserName}} on Edge Filer 
      {{EdgeFiler}} within 5 minutes. Please investigate unauthorized access attempts or misconfigurations.
customDetails:
    TenantName: TenantName
    UserName: UserName
    EdgeFiler: EdgeFiler
    RootPath: RootPath
    Share: Share
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: UserName
  - entityType: File
    fieldMappings:
      - identifier: Name
        columnName: EdgeFiler
suppressionDuration: PT5H
suppressionEnabled: false
version: 1.0.0

Stages and Predicates

Stage 1: source

Syslog

Stage 2: where

| where ProcessName == 'gw-audit'

Stage 3: extend

| extend
      TenantName = extract("\"vportal\":\"([^\"]*)\"", 1, SyslogMessage),
      UserName = extract("user=([^|]*)", 1, SyslogMessage),
      Operation = extract("op=([^|]*)", 1, SyslogMessage),
      EdgeFiler = extract("\"client\":\"([^\"]*)\"", 1, SyslogMessage),
      RootPath = extract("rootPath=([^|]*)", 1, SyslogMessage),
      Share = extract("share=([^|]*)", 1, SyslogMessage),
      LocalPath = extract("path=([^|]*)", 1, SyslogMessage),
      Timestamp = todatetime(extract("\"@timestamp\":\"([^\"]*)\"", 1, SyslogMessage))

Stage 4: where

| where Operation in ('ACLAdded', 'ACLDeleted', 'ACLProtectionAdded','chown', 'setsd', 'ACLProtectionDeleted', 'ACEChanged', 'setdacl')

Stage 5: summarize

| summarize Count = count() by UserName, bin(Timestamp, 5m)

Stage 6: where

| where Count > 5000

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Countgt
  • 5000
field:"Count" kind:gt value:"5000"
Operationin
  • ACEChanged
  • ACLAdded
  • ACLDeleted
  • ACLProtectionAdded
  • ACLProtectionDeleted
  • chown
  • setdacl
  • setsd
field:"Operation" kind:in
ProcessNameeq
  • gw-audit
field:"process_name" kind:eq value:"gw-audit"

Output fields

These fields are emitted when the rule matches.

FieldSource
Countsummarize
UserNamesummarize