Detection rules › Sigma

Delete Defender Scan ShellEx Context Menu Registry Key

Severity
medium
Author
Matt Anderson (Huntress)
Source
upstream

Detects deletion of registry key that adds 'Scan with Defender' option in context menu. Attackers may use this to make it harder for users to scan files that are suspicious.

Event coverage

ProviderEvent IDTitle
Sysmon14RegistryEvent (Key and Value Rename)

Stages and Predicates

Stage 1: selection

TargetObject|contains: 'shellex\ContextMenuHandlers\EPP'

Stage 2: not 1 of filter_main_defender

or:
Image|startswith: 'C:\Program Files (x86)\Windows Defender\'
Image|startswith: 'C:\Program Files\Windows Defender\'
Image|startswith: 'C:\ProgramData\Microsoft\Windows Defender\Platform\'
Image|endswith: '\MsMpEng.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
  • \MsMpEng.exe corpus 13 (sigma 13)
Imagestarts_with
  • C:\Program Files (x86)\Windows Defender\ corpus 5 (sigma 5)
  • C:\Program Files\Windows Defender\ corpus 5 (sigma 5)
  • C:\ProgramData\Microsoft\Windows Defender\Platform\ corpus 7 (sigma 7)
TargetObjectmatch
  • shellex\ContextMenuHandlers\EPP