Suspicious Binary In User Directory Spawned From Office Application

Severity: high
Author: Jason Lynch
Source: upstream

Detects an executable in the users directory started from one of the Microsoft Office suite applications (Word, Excel, PowerPoint, Publisher, Visio)

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1204.002` User Execution: Malicious File

Event coverage

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

Stages and Predicates

Stage 1: `selection`

or:
ParentImage|endswith: '\EQNEDT32.exe'
ParentImage|endswith: '\EXCEL.EXE'
ParentImage|endswith: '\MSACCESS.exe'
ParentImage|endswith: '\MSPUB.exe'
ParentImage|endswith: '\POWERPNT.exe'
ParentImage|endswith: '\VISIO.exe'
ParentImage|endswith: '\WINWORD.EXE'
Image|endswith: .exe
Image|startswith: 'C:\users\'

Stage 2: `not filter`

Image|endswith: '\Teams.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.

Field	Kind	Values
`Image`	ends_with	`.exe` corpus 4 (sigma 4) `\Teams.exe` corpus 4 (sigma 4)
`Image`	starts_with	`C:\users\`
`ParentImage`	ends_with	`\EQNEDT32.exe` `\EXCEL.EXE` corpus 3 (sigma 3) `\MSACCESS.exe` `\MSPUB.exe` corpus 3 (sigma 3) `\POWERPNT.exe` corpus 3 (sigma 3) `\VISIO.exe` corpus 3 (sigma 3) `\WINWORD.EXE` corpus 3 (sigma 3)