Sigma rule: Suspicious New Instance Of An Office COM Object

Rule

Title

Suspicious New Instance Of An Office COM Object

Status

test

Level

medium

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2022-10-13

Modified

2023-12-19

File

rules-threat-hunting/windows/process_creation/proc_creation_win_office_svchost_parent.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects an svchost process spawning an instance of an office application. This happens when the initial word application creates an instance of one of the Office COM objects such as 'Word.Application', 'Excel.Application', etc.
This can be used by malicious actors to create malicious Office documents with macros on the fly. (See vba2clr project in the references)

Log source

product

windows

category

process_creation

Detection

selection:
    ParentImage|endswith: '\svchost.exe'
    Image|endswith:
        - '\eqnedt32.exe'
        - '\excel.exe'
        - '\msaccess.exe'
        - '\mspub.exe'
        - '\powerpnt.exe'
        - '\visio.exe'
        - '\winword.exe'
condition: selection

False positives (as the rule lists them)

• Legitimate usage of office automation via scripting

Tags

• attack.execution
• detection.threat-hunting
• attack.stealth

References

• https://learn.microsoft.com/en-us/previous-versions/office/troubleshoot/office-developer/automate-word-create-file-using-visual-basic
• https://github.com/med0x2e/vba2clr

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-threat-hunting/windows/process_creation/proc_creation_win_office_svchost_parent.yml