Sigma rule: Certificate Request Export to Exchange Webserver

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-d15268016f1d, updated 2023-01-23T00:00:00.000Z.

Rule

Title
Certificate Request Export to Exchange Webserver
Status
test
Level
critical
Author
Max Altgelt (Nextron Systems)
Date
2021-08-23
Modified
2023-01-23
File
rules/windows/builtin/msexchange/win_exchange_proxyshell_certificate_generation.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects a write of an Exchange CSR to an untypical directory or with aspx name suffix which can be used to place a webshell

Log source

product
windows
service
msexchange-management

Detection

keywords_export_command:
    '|all':
        - 'New-ExchangeCertificate'
        - ' -GenerateRequest'
        - ' -BinaryEncoded'
        - ' -RequestFile'
keywords_export_params:
    - '\\\\localhost\\C$'
    - '\\\\127.0.0.1\\C$'
    - 'C:\\inetpub'
    - '.aspx'
condition: keywords_export_command and keywords_export_params

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.persistence
  • attack.t1505.003

MITRE ATT&CK ids this rule names

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/windows/builtin/msexchange/win_exchange_proxyshell_certificate_generation.yml

Sources and licences

  • SigmaHQ

    "Certificate Request Export to Exchange Webserver" by Max Altgelt (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/msexchange/win_exchange_proxyshell_certificate_generation.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: Certificate Request Export to Exchange Webserver",
entity page, dataset version ref-d15268016f1d, updated 2023-01-23T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/b7bc7038-638b-4ffd-880c-292c692209ef (accessed 2026-11-03).
Underlying source: SigmaHQ rule b7bc7038-638b-4ffd-880c-292c692209ef, 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.