Schtasks From Suspicious Folders

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

Detects scheduled task creations that have suspicious action command and folder combinations

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1053.005` Scheduled Task/Job: Scheduled Task
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: `all of selection_img`

or:
Image|endswith: '\schtasks.exe'
OriginalFileName: schtasks.exe

Stage 2: `all of selection_create`

CommandLine|contains: ' /create '

Stage 3: `all of selection_command`

or:
CommandLine|contains: 'cmd /c '
CommandLine|contains: 'cmd /k '
CommandLine|contains: 'cmd /r '
CommandLine|contains: 'cmd.exe /c '
CommandLine|contains: 'cmd.exe /k '
CommandLine|contains: 'cmd.exe /r '
CommandLine|contains: powershell
CommandLine|contains: pwsh

Stage 4: `all of selection_all_folders`

or:
CommandLine|contains: '%ProgramData%'
CommandLine|contains: 'C:\ProgramData\'

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
`CommandLine`	match	`/create` corpus 14 (sigma 14) `%ProgramData%` corpus 4 (sigma 4) `C:\ProgramData\` corpus 6 (sigma 6) `cmd /c` corpus 5 (sigma 5) `cmd /k` corpus 5 (sigma 5) `cmd /r` corpus 5 (sigma 5) `cmd.exe /c` corpus 6 (sigma 6) `cmd.exe /k` corpus 6 (sigma 6) `cmd.exe /r` corpus 6 (sigma 6) `powershell` corpus 16 (sigma 16) `pwsh` corpus 5 (sigma 5)
`Image`	ends_with	`\schtasks.exe` corpus 45 (sigma 45)
`OriginalFileName`	eq	`schtasks.exe` corpus 14 (sigma 14)

Schtasks From Suspicious Folders

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: all of selection_img

Stage 2: all of selection_create

Stage 3: all of selection_command

Stage 4: all of selection_all_folders

Indicators

Stage 1: `all of selection_img`

Stage 2: `all of selection_create`

Stage 3: `all of selection_command`

Stage 4: `all of selection_all_folders`