Sigma rule: Excel Proxy Executing Regsvr32 With Payload

Rule

Title

Excel Proxy Executing Regsvr32 With Payload

Status

deprecated

Level

high

Author

Vadim Khrykov (ThreatIntel), Cyb3rEng (Rule)

Date

2021/08/23

Modified

2022/12/02

File

deprecated/windows/proc_creation_win_office_from_proxy_executing_regsvr32_payload.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Excel called wmic to finally proxy execute regsvr32 with the payload.
An attacker wanted to break suspicious parent-child chain (Office app spawns LOLBin).
But we have command-line in the event which allow us to "restore" this suspicious parent-child chain and detect it.
Monitor process creation with "wmic process call create" and LOLBins in command-line with parent Office application processes.

Log source

product

windows

category

process_creation

Detection

#useful_information: add more LOLBins to the rules logic of your choice.
selection_img:
    - Image|endswith: '\wbem\WMIC.exe'
    - OriginalFileName: 'wmic.exe'
selection_other:
    CommandLine|contains:
        - 'regsvr32'
        - 'rundll32'
        - 'msiexec'
        - 'mshta'
        - 'verclsid'
    ParentImage|endswith:
        - '\winword.exe'
        - '\excel.exe'
        - '\powerpnt.exe'
    CommandLine|contains|all:
        - 'process'
        - 'create'
        - 'call'
condition: all of selection_*

False positives (as the rule lists them)

• Unknown

Tags

• attack.t1204.002
• attack.t1047
• attack.t1218.010
• attack.execution
• attack.defense_evasion

MITRE ATT&CK ids this rule names

• T1047
• T1204.002
• T1218.010

References

• https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
• https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/deprecated/windows/proc_creation_win_office_from_proxy_executing_regsvr32_payload.yml