Office Macro File Creation From Suspicious Process

Severity: high
Author: frack113, Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects the creation of a office macro file from a a suspicious process

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1566.001` Phishing: Spearphishing Attachment

Event coverage

Provider	Event ID	Title
Sysmon	11	FileCreate

Stages and Predicates

Stage 1: `all of selection_cmd`

or:
Image|endswith: '\cscript.exe'
Image|endswith: '\mshta.exe'
Image|endswith: '\regsvr32.exe'
Image|endswith: '\rundll32.exe'
Image|endswith: '\wscript.exe'
ParentImage|endswith: '\cscript.exe'
ParentImage|endswith: '\mshta.exe'
ParentImage|endswith: '\regsvr32.exe'
ParentImage|endswith: '\rundll32.exe'
ParentImage|endswith: '\wscript.exe'

Stage 2: `all of selection_ext`

or:
TargetFilename|endswith: .docm
TargetFilename|endswith: .dotm
TargetFilename|endswith: .potm
TargetFilename|endswith: .pptm
TargetFilename|endswith: .xlsm
TargetFilename|endswith: .xltm

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	`\cscript.exe` corpus 64 (sigma 64) `\mshta.exe` corpus 57 (sigma 57) `\regsvr32.exe` corpus 57 (sigma 57) `\rundll32.exe` corpus 76 (sigma 76) `\wscript.exe` corpus 64 (sigma 64)
`ParentImage`	ends_with	`\cscript.exe` corpus 14 (sigma 14) `\mshta.exe` corpus 10 (sigma 10) `\regsvr32.exe` corpus 11 (sigma 11) `\rundll32.exe` corpus 12 (sigma 12) `\wscript.exe` corpus 14 (sigma 14)
`TargetFilename`	ends_with	`.docm` corpus 5 (sigma 5) `.dotm` corpus 5 (sigma 5) `.potm` corpus 3 (sigma 3) `.pptm` corpus 3 (sigma 3) `.xlsm` corpus 5 (sigma 5) `.xltm` corpus 5 (sigma 5)