Potential Persistence Via Powershell Search Order Hijacking - Task

Severity: high
Author: pH-T (Nextron Systems), Florian Roth (Nextron Systems)
Source: upstream

Detects suspicious powershell execution via a schedule task where the command ends with an suspicious flags to hide the powershell instance instead of executeing scripts or commands. This could be a sign of persistence via PowerShell "Get-Variable" technique as seen being used in Colibri Loader

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1053.005` Scheduled Task/Job: Scheduled Task, `T1059.001` Command and Scripting Interpreter: PowerShell
Persistence	`T1053.005` Scheduled Task/Job: Scheduled Task
Privilege Escalation	`T1053.005` Scheduled Task/Job: Scheduled Task

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection`

or:
CommandLine|endswith: ' -ep bypass'
CommandLine|endswith: ' -noni'
CommandLine|endswith: ' -w hidden'
CommandLine|endswith: ' -windowstyle hidden'
ParentCommandLine|contains: '-k netsvcs'
ParentCommandLine|contains: '-s Schedule'
ParentImage: 'C:\WINDOWS\System32\svchost.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.