LoFP LoFP / none identified. attempts to add deny aces to services, especially security-related services should be immediately investigated.

Techniques

Sample rules

Windows New Deny Permission Set On Service SD Via Sc.EXE

Description

The following analytic detects changes in a service security descriptor where a new deny ace has been added. It leverages data from Endpoint Detection and Response (EDR) agents, specifically searching for any process execution involving the “sc.exe” binary with the “sdset” flag targeting any service and adding a dedicated deny ace. If confirmed malicious, this could allow an attacker to escalate their privileges, blind defenses and more.

Detection logic


| tstats `security_content_summariesonly` values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process_name=sc.exe OR Processes.original_file_name=sc.exe) Processes.process="*sdset *" Processes.process="*(D;*" Processes.process IN ("*;IU*", "*;S-1-5-4*", "*;SU*", "*;S-1-5-6*", "*;BA*", "*;S-1-5-32-544*", "*;SY*", "*;S-1-5-18*", "*;WD*", "*;S-1-1-0*", "*;AU*", "*;S-1-5-11*", "*;LS*", "*;S-1-5-19*") by Processes.dest Processes.user Processes.parent_process Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_new_deny_permission_set_on_service_sd_via_sc_exe_filter`