Potential Dropper Script Execution Via WScript/CScript

Severity: medium
Author: Margaritis Dimitrios (idea), Florian Roth (Nextron Systems), oscd.community, Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects wscript/cscript executions of scripts located in user directories

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.005` Command and Scripting Interpreter: Visual Basic, `T1059.007` Command and Scripting Interpreter: JavaScript

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_exec`

or:
Image|endswith: '\cscript.exe'
Image|endswith: '\wscript.exe'

Stage 2: `all of selection_paths`

or:
CommandLine|contains: ':\Temp\'
CommandLine|contains: ':\Tmp\'
CommandLine|contains: ':\Users\Public\'
CommandLine|contains: ':\Windows\Temp\'
CommandLine|contains: '\AppData\Local\Temp\'

Stage 3: `all of selection_ext`

or:
CommandLine|contains: .js
CommandLine|contains: .jse
CommandLine|contains: .vba
CommandLine|contains: .vbe
CommandLine|contains: .vbs
CommandLine|contains: .wsf

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	`.js` corpus 6 (sigma 6) `.jse` `.vba` `.vbe` corpus 4 (sigma 4) `.vbs` corpus 5 (sigma 5) `.wsf` corpus 2 (sigma 2) `:\Temp\` corpus 14 (sigma 14) `:\Tmp\` corpus 2 (sigma 2) `:\Users\Public\` corpus 14 (sigma 14) `:\Windows\Temp\` corpus 15 (sigma 15) `\AppData\Local\Temp\` corpus 16 (sigma 16)
`Image`	ends_with	`\cscript.exe` corpus 64 (sigma 64) `\wscript.exe` corpus 64 (sigma 64)