Sigma rule: Regsvr32 Execution From Highly Suspicious Location

Rule

Title

Regsvr32 Execution From Highly Suspicious Location

Status

test

Level

high

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2023-05-26

File

rules/windows/process_creation/proc_creation_win_regsvr32_susp_exec_path_2.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects execution of regsvr32 where the DLL is located in a highly suspicious locations

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith: '\regsvr32.exe'
    - OriginalFileName: 'REGSVR32.EXE'
selection_path_1:
    CommandLine|contains:
        - ':\PerfLogs\'
        - ':\Temp\'
        - '\Windows\Registration\CRMLog'
        - '\Windows\System32\com\dmp\'
        - '\Windows\System32\FxsTmp\'
        - '\Windows\System32\Microsoft\Crypto\RSA\MachineKeys\'
        - '\Windows\System32\spool\drivers\color\'
        - '\Windows\System32\spool\PRINTERS\'
        - '\Windows\System32\spool\SERVERS\'
        - '\Windows\System32\Tasks_Migrated\'
        - '\Windows\System32\Tasks\Microsoft\Windows\SyncCenter\'
        - '\Windows\SysWOW64\com\dmp\'
        - '\Windows\SysWOW64\FxsTmp\'
        - '\Windows\SysWOW64\Tasks\Microsoft\Windows\PLA\System\'
        - '\Windows\SysWOW64\Tasks\Microsoft\Windows\SyncCenter\'
        - '\Windows\Tasks\'
        - '\Windows\Tracing\'
selection_path_2:
    CommandLine|contains:
        # This is to avoid collisions with CLI starting with "C:\"
        - ' "C:\'
        - ' C:\'
        - " 'C:\\"
        - 'D:\'
selection_exclude_known_dirs:
    CommandLine|contains:
        # Note: add additional locations that are related to third party applications
        - 'C:\Program Files (x86)\'
        - 'C:\Program Files\'
        - 'C:\ProgramData\'
        - 'C:\Users\'
        # Note: The space added here are to avoid collisions with the "regsvr32" binary full path
        - ' C:\Windows\'
        - ' "C:\Windows\'
        - " 'C:\\Windows\\"
filter_main_empty:
    CommandLine: ''
filter_main_null:
    CommandLine: null
condition: selection_img and (selection_path_1 or (selection_path_2 and not selection_exclude_known_dirs)) and not 1 of filter_main_*

False positives (as the rule lists them)

• Unlikely

Tags

• attack.stealth
• attack.t1218.010

MITRE ATT&CK ids this rule names

• T1218.010

References

• Internal Research

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_regsvr32_susp_exec_path_2.yml