Suspicious File Drop by Exchange (via file_event)

title: Suspicious File Drop by Exchange (via file_event)
id: 2e601407-1cb6-5093-9377-da77050e8529
status: stable
description: This rule detects anomalous file type dropped by an Exchange component in IIS
references:
    - https://attack.mitre.org/techniques/T1505/003/
    - https://attack.mitre.org/techniques/T1190/
    - https://www.microsoft.com/security/blog/2022/09/30/analyzing-attacks-using-the-exchange-vulnerabilities-cve-2022-41040-and-cve-2022-41082/
    - https://www.gteltsc.vn/blog/canh-bao-chien-dich-tan-cong-su-dung-lo-hong-zero-day-tren-microsoft-exchange-server-12714.html
    - https://en.gteltsc.vn/blog/cap-nhat-nhe-ve-lo-hong-bao-mat-0day-microsoft-exchange-dang-duoc-su-dung-de-tan-cong-cac-to-chuc-tai-viet-nam-9685.html
author: Huntrule Team
date: 2026-07-25
tags:
    - attack.persistence
    - attack.t1190
    - attack.initial-access
    - attack.t1505.003
logsource:
    product: windows
    category: file_event
detection:
    selection:
        Image|endswith: '\w3wp.exe'
        CommandLine|contains: 'MSExchange'
    selection_types:
        TargetFilename|endswith:
            - '.aspx'
            - '.asp'
            - '.ashx'
            - '.ps1'
            - '.bat'
            - '.exe'
            - '.dll'
            - '.vbs'
    condition: all of selection*
falsepositives:
    - Unknown
level: medium