Path To Screensaver Binary Modified

Severity: medium
Author: Bartlomiej Czyz @bczyz1, oscd.community
Source: upstream

Detects value modification of registry key containing path to binary used as screensaver.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1546.002` Event Triggered Execution: Screensaver
Privilege Escalation	`T1546.002` Event Triggered Execution: Screensaver

Event coverage

Provider	Event ID	Title
Sysmon	12	RegistryEvent (Object create and delete)
Sysmon	13	RegistryEvent (Value Set)
Sysmon	14	RegistryEvent (Key and Value Rename)

Stages and Predicates

Stage 1: `selection`

TargetObject|endswith: '\Control Panel\Desktop\SCRNSAVE.EXE'

Stage 2: `not filter`

or:
Image|endswith: '\explorer.exe'
Image|endswith: '\rundll32.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.

Field	Kind	Values
`Image`	ends_with	`\explorer.exe` corpus 12 (sigma 12) `\rundll32.exe` corpus 76 (sigma 76)
`TargetObject`	ends_with	`\Control Panel\Desktop\SCRNSAVE.EXE`