Sigma rule: Suspicious ASPX File Drop by Exchange
A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-d72c2ddd5f6d, updated 2022-10-01T00:00:00.000Z.
Rule
- Title
- Suspicious ASPX File Drop by Exchange
- Status
- test
- Level
- high
- Author
- Florian Roth (Nextron Systems), MSTI (query, idea)
- Date
- 2022-10-01
- File
- rules/windows/file/file_event/file_event_win_exchange_webshell_drop.yml
- Commit
- ccbb0369507f796db0b0ae6854c8a2be471b9d84
Detects suspicious file type dropped by an Exchange component in IIS into a suspicious folder
Log source
- product
- windows
- category
- file_event
Detection
selection:
Image|endswith: '\w3wp.exe'
CommandLine|contains: 'MSExchange'
TargetFilename|contains:
- 'FrontEnd\HttpProxy\' # from GTSC and MSTI reports
- '\inetpub\wwwroot\aspnet_client\' # from GTSC report
selection_types:
TargetFilename|endswith:
- '.aspx'
- '.asp'
- '.ashx'
condition: all of selection*False positives (as the rule lists them)
- Unknown
Tags
- attack.persistence
- attack.t1505.003
MITRE ATT&CK ids this rule names
Related rules
References
- 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
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/file/file_event/file_event_win_exchange_webshell_drop.yml
Sources and licences
SigmaHQ
"Suspicious ASPX File Drop by Exchange" by Florian Roth (Nextron Systems), MSTI (query, idea) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/file/file_event/file_event_win_exchange_webshell_drop.yml.
Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License
Cite this page
Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious ASPX File Drop by Exchange",
entity page, dataset version ref-d72c2ddd5f6d, updated 2022-10-01T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/bd1212e5-78da-431e-95fa-c58e3237a8e6 (accessed 2026-11-03).
Underlying source: SigmaHQ rule bd1212e5-78da-431e-95fa-c58e3237a8e6, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.
Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.