Network endpoint to host executable correlation

Status: available
Severity: medium
Time window: 1d
Group by: shortFileName, suspectExeName
Source: github.com/Azure/Azure-Sentinel

'Correlates blocked URLs hosting [malicious] executables with host endpoint data to identify potential instances of executables of the same name having been recently run.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1204` User Execution

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

id: 01f64465-b1ef-41ea-a7f5-31553a11ad43
name: Network endpoint to host executable correlation
description: |
  'Correlates blocked URLs hosting [malicious] executables with host endpoint data to identify potential instances of executables of the same name having been recently run.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: TrendMicro
    dataTypes:
      - CommonSecurityLog
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes: 
      - SecurityEvents 
  - connectorId: WindowsForwardedEvents
    dataTypes: 
      - WindowsEvent 
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Execution
relevantTechniques:
  - T1204
query: |
  let endpointData = 
  (union isfuzzy=true
  (SecurityEvent
    | where EventID == 4688
    | extend shortFileName = tolower(tostring(split(NewProcessName, '\\')[-1]))
    ),
    (WindowsEvent
    | where EventID == 4688
    | extend  NewProcessName = tostring(EventData.NewProcessName)
    | extend shortFileName = tolower(tostring(split(NewProcessName, '\\')[-1]))
    | extend TargetUserName = tostring(EventData.TargetUserName)
    ));
  // Correlate suspect executables seen in TrendMicro rule updates with similar activity on endpoints
  CommonSecurityLog
  | where DeviceVendor =~ "Trend Micro"
  | where Activity =~ "Deny List updated" 
  | where RequestURL endswith ".exe"
  | project TimeGenerated, Activity , RequestURL , SourceIP, DestinationIP
  | extend suspectExeName = tolower(tostring(split(RequestURL, '/')[-1]))
  | join kind=innerunique (endpointData) on $left.suspectExeName == $right.shortFileName 
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: TargetUserName
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: DestinationIP
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: RequestURL
version: 1.1.6
kind: Scheduled

Stages and Predicates

Let binding: `endpointData` used in Stages 1, 8

let endpointData = (union isfuzzy=true
(SecurityEvent
  | where EventID == 4688
  | extend shortFileName = tolower(tostring(split(NewProcessName, '\\')[-1]))
  ),
  (WindowsEvent
  | where EventID == 4688
  | extend  NewProcessName = tostring(EventData.NewProcessName)
  | extend shortFileName = tolower(tostring(split(NewProcessName, '\\')[-1]))
  | extend TargetUserName = tostring(EventData.TargetUserName)
  ));

Stage 1: `source`

let endpointData

Stage 2: `source`

CommonSecurityLog

Stage 3: `where`

| where DeviceVendor =~ "Trend Micro"

Stage 4: `where`

| where Activity =~ "Deny List updated"

Stage 5: `where`

| where RequestURL endswith ".exe"

Stage 6: `project`

| project TimeGenerated, Activity , RequestURL , SourceIP, DestinationIP

Stage 7: `extend`

| extend suspectExeName = tolower(tostring(split(RequestURL, '/')[-1]))

Stage 8: `join`

| join kind=innerunique (endpointData) on $left.suspectExeName == $right.shortFileName

Stage 9: `extend`

| extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Activity`	eq	`Deny List updated`	`field:"Activity" kind:eq value:"Deny List updated"`
`DeviceVendor`	eq	`Trend Micro`	`field:"DeviceVendor" kind:eq value:"Trend Micro"`
`EventID`	eq	`4688` corpus 317 (splunk 283, kusto 33, elastic 1)	`field:"EventID" kind:eq value:"4688"`
`RequestURL`	ends_with	`.exe`	`field:"RequestURL" kind:ends_with value:".exe"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`Activity`	`project`
`DestinationIP`	`project`
`RequestURL`	`project`
`SourceIP`	`project`
`TimeGenerated`	`project`
`suspectExeName`	`extend`
`DnsDomain`	`extend`
`HostName`	`extend`

Network endpoint to host executable correlation

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Let binding: endpointData used in Stages 1, 8

Stage 1: source

Stage 2: source

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: project

Stage 7: extend

Stage 8: join

Stage 9: extend