Detection rules › Sigma

ADSI-Cache File Creation By Uncommon Tool

Severity
medium
Author
xknow @xknow_infosec, Tim Shelton
Source
upstream

Detects the creation of an "Active Directory Schema Cache File" (.sch) file by an uncommon tool.

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1001.003 Data Obfuscation: Protocol or Service Impersonation

Event coverage

ProviderEvent IDTitle
Sysmon11FileCreate

Stages and Predicates

Stage 1: selection

TargetFilename|endswith: .sch
TargetFilename|contains: '\Local\Microsoft\Windows\SchCache\'

Stage 2: not 1 of filter_main_*

or:
Image|endswith: '\OUTLOOK.EXE'
Image|contains: ':\Program Files\'
Image|contains: '\Microsoft Office'
Image|endswith: ':\Program Files\Cylance\Desktop\CylanceSvc.exe'
Image|endswith: ':\Windows\CCM\CcmExec.exe'
Image|endswith: ':\Windows\System32\wbem\WmiPrvSE.exe'
Image|endswith: ':\Windows\system32\dsac.exe'
Image|endswith: ':\Windows\system32\efsui.exe'
Image|endswith: ':\windows\system32\WindowsPowerShell\v1.0\powershell.exe'
Image|endswith: ':\windows\system32\dllhost.exe'
Image|endswith: ':\windows\system32\mmc.exe'
Image|endswith: ':\windows\system32\svchost.exe'
Image|contains: ':\Program Files\SentinelOne\Sentinel Agent'
Image|contains: ':\Windows\ccmsetup\autoupgrade\ccmsetup'

Stage 3: not 1 of filter_optional_*

or:
Image|endswith: ':\Program Files\Citrix\Receiver StoreFront\Services\DefaultDomainServices\Citrix.DeliveryServices.DomainServices.ServiceHost.exe'
Image|endswith: '\LANDesk\LDCLient\ldapwhoami.exe'

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
Imageends_with
  • :\Program Files\Citrix\Receiver StoreFront\Services\DefaultDomainServices\Citrix.DeliveryServices.DomainServices.ServiceHost.exe
  • :\Program Files\Cylance\Desktop\CylanceSvc.exe
  • :\Windows\CCM\CcmExec.exe
  • :\Windows\System32\wbem\WmiPrvSE.exe
  • :\Windows\system32\dsac.exe
  • :\Windows\system32\efsui.exe
  • :\windows\system32\WindowsPowerShell\v1.0\powershell.exe
  • :\windows\system32\dllhost.exe
  • :\windows\system32\mmc.exe
  • :\windows\system32\svchost.exe corpus 2 (sigma 2)
  • \LANDesk\LDCLient\ldapwhoami.exe
  • \OUTLOOK.EXE corpus 3 (sigma 3)
Imagematch
  • :\Program Files\ corpus 6 (sigma 6)
  • :\Program Files\SentinelOne\Sentinel Agent
  • :\Windows\ccmsetup\autoupgrade\ccmsetup
  • \Microsoft Office
TargetFilenameends_with
  • .sch
TargetFilenamematch
  • \Local\Microsoft\Windows\SchCache\