Detectionhightest
Suspicious ASPX File Drop by Exchange
Detects suspicious file type dropped by an Exchange component in IIS into a suspicious folder
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Florian Roth (Nextron Systems), MSTI (query, idea)Created Sat Oct 01bd1212e5-78da-431e-95fa-c58e3237a8e6windows
Log Source
WindowsFile Event
ProductWindows← raw: windows
CategoryFile Event← raw: file_event
Events for file system activity including creation, modification, and deletion.
Detection Logic
Detection Logic2 selectors
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
Unknown
False positive likelihood has not been assessed. Additional context may be needed during triage.
MITRE ATT&CK
Tactics
Sub-techniques
Rule Metadata
Rule ID
bd1212e5-78da-431e-95fa-c58e3237a8e6
Status
test
Level
high
Type
Detection
Created
Sat Oct 01
Path
rules/windows/file/file_event/file_event_win_exchange_webshell_drop.yml
Raw Tags
attack.persistenceattack.t1505.003