PUA - DefenderCheck Execution

Severity: high
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects the use of DefenderCheck, a tool to evaluate the signatures used in Microsoft Defender. It can be used to figure out the strings / byte chains used in Microsoft Defender to detect a tool and thus used for AV evasion.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1027.005` Obfuscated Files or Information: Indicator Removal from Tools

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection`

or:
Description: DefenderCheck
Image|endswith: '\DefenderCheck.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.