Hijack Execution Flow - DLL Side-Loading

Back


Id	3084b487-fad6-4000-9544-6085b9657290
Rulename	Hijack Execution Flow - DLL Side-Loading
Description	This detection tries to identify all DLLs loaded by “high integrity” processes and cross-checks the DLL paths against FileCreate/FileModify events of the same DLL by a medium integrity process. Of course, we need to do some magic to filter out false positives as much as possible. So any FileCreate/FileModify done by “NT Authoriy\System” and the “RID 500” users aren’t interesting. Also, we only want to see the FileCreate/FileModify actions which are performed with a default or limited token elevation. If done with a full elevated token, the user is apparently admin already.
Severity	Medium
Tactics	Persistence PrivilegeEscalation DefenseEvasion
Techniques	T1574.002
Required data connectors	MicrosoftThreatProtection
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/DLLSideLoading.yaml
Version	1.0.1
Arm template	3084b487-fad6-4000-9544-6085b9657290.json

KQL

let imls = materialize(
    DeviceImageLoadEvents
    | where InitiatingProcessIntegrityLevel in ("High", "System") and FileName !endswith ".exe"
    | project FolderPath=tolower(FolderPath), InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
    | distinct FolderPath, InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
);
imls
| join (
    DeviceFileEvents
    | where FolderPath in~ ((imls | project FolderPath)) and ActionType in ("FileCreated", "FileModified") and
    InitiatingProcessIntegrityLevel !in ("High", "System", "") and InitiatingProcessAccountSid != "S-1-5-18" and
    InitiatingProcessTokenElevation in ("TokenElevationTypeDefault", "TokenElevationTypeLimited") and InitiatingProcessAccountSid !endswith "-500"
    | extend FolderPath=tolower(FolderPath)
) on FolderPath, DeviceId, DeviceName
| project-away FolderPath1

YAML

relevantTechniques:
- T1574.002
name: Hijack Execution Flow - DLL Side-Loading
triggerThreshold: 0
tactics:
- Persistence
- PrivilegeEscalation
- DefenseEvasion
severity: Medium
id: 3084b487-fad6-4000-9544-6085b9657290
status: Available
requiredDataConnectors:
- dataTypes:
  - DeviceFileEvents
  - DeviceImageLoadEvents
  connectorId: MicrosoftThreatProtection
kind: Scheduled
query: |
  let imls = materialize(
      DeviceImageLoadEvents
      | where InitiatingProcessIntegrityLevel in ("High", "System") and FileName !endswith ".exe"
      | project FolderPath=tolower(FolderPath), InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
      | distinct FolderPath, InitiatingProcessFileName, InitiatingProcessIntegrityLevel, DeviceId, DeviceName
  );
  imls
  | join (
      DeviceFileEvents
      | where FolderPath in~ ((imls | project FolderPath)) and ActionType in ("FileCreated", "FileModified") and
      InitiatingProcessIntegrityLevel !in ("High", "System", "") and InitiatingProcessAccountSid != "S-1-5-18" and
      InitiatingProcessTokenElevation in ("TokenElevationTypeDefault", "TokenElevationTypeLimited") and InitiatingProcessAccountSid !endswith "-500"
      | extend FolderPath=tolower(FolderPath)
  ) on FolderPath, DeviceId, DeviceName
  | project-away FolderPath1  
description: |
  This detection tries to identify all DLLs loaded by "high integrity" processes and cross-checks the DLL paths against FileCreate/FileModify events of the same DLL by a medium integrity process.
  Of course, we need to do some magic to filter out false positives as much as possible. So any FileCreate/FileModify done by "NT Authoriy\System" and the "RID 500" users aren't interesting.
  Also, we only want to see the FileCreate/FileModify actions which are performed with a default or limited token elevation. If done with a full elevated token, the user is apparently admin already.  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/DLLSideLoading.yaml
triggerOperator: gt
queryPeriod: 1h
queryFrequency: 1h
version: 1.0.1
entityMappings:
- entityType: Host
  fieldMappings:
  - columnName: DeviceName
    identifier: FullName
- entityType: Account
  fieldMappings:
  - columnName: InitiatingProcessAccountSid
    identifier: Sid
  - columnName: InitiatingProcessAccountName
    identifier: Name
  - columnName: InitiatingProcessAccountDomain
    identifier: NTDomain
- entityType: Process
  fieldMappings:
  - columnName: InitiatingProcessCommandLine
    identifier: CommandLine

ARM