Sigma rule: Successful Exchange ProxyShell Attack

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-2a43a140eca0, updated 2023-01-02T00:00:00.000Z.

Rule

Title
Successful Exchange ProxyShell Attack
Status
test
Level
critical
Author
Florian Roth (Nextron Systems), Rich Warren
Date
2021-08-09
Modified
2023-01-02
File
rules-emerging-threats/2021/Exploits/ProxyShell-Exploit/web_exchange_proxyshell_successful.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects URP patterns and status codes that indicate a successful ProxyShell exploitation attack against Exchange servers

Log source

category
webserver

Detection

selection_auto:
    cs-uri-query|contains: '/autodiscover.json'
selection_uri:
    cs-uri-query|contains:
        - '/powershell'
        - '/mapi/nspi'
        - '/EWS'
        - 'X-Rps-CAT'
selection_success:
    sc-status:
        - 200
        - 301
condition: selection_auto and selection_uri and selection_success

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.initial-access
  • detection.emerging-threats

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/ProxyShell-Exploit/web_exchange_proxyshell_successful.yml

Sources and licences

  • SigmaHQ

    "Successful Exchange ProxyShell Attack" by Florian Roth (Nextron Systems), Rich Warren (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/ProxyShell-Exploit/web_exchange_proxyshell_successful.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Successful Exchange ProxyShell Attack",
entity page, dataset version ref-2a43a140eca0, updated 2023-01-02T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/992be1eb-e5da-437e-9a54-6d13b57bb4d8 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 992be1eb-e5da-437e-9a54-6d13b57bb4d8, 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.