Sigma rule: Outbound Network Connection Initiated By Cmstp.EXE

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-7cfb0dd39f87, updated 2024-05-31T00:00:00.000Z.

Rule

Title
Outbound Network Connection Initiated By Cmstp.EXE
Status
test
Level
high
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2022-08-30
Modified
2024-05-31
File
rules/windows/network_connection/net_connection_win_cmstp_initiated_connection.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects a network connection initiated by Cmstp.EXE
Its uncommon for "cmstp.exe" to initiate an outbound network connection. Investigate the source of such requests to determine if they are malicious.

Log source

product
windows
category
network_connection

Detection

selection:
    Image|endswith: '\cmstp.exe'
    Initiated: 'true'
filter_main_local_ranges:
    DestinationIp|cidr:
        - '127.0.0.0/8'
        - '10.0.0.0/8'
        - '172.16.0.0/12'
        - '192.168.0.0/16'
        - '169.254.0.0/16'
        - '::1/128'  # IPv6 loopback
        - 'fe80::/10'  # IPv6 link-local addresses
        - 'fc00::/7'  # IPv6 private addresses
condition: selection and not 1 of filter_main_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.stealth
  • attack.t1218.003

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/network_connection/net_connection_win_cmstp_initiated_connection.yml

Sources and licences

  • SigmaHQ

    "Outbound Network Connection Initiated By Cmstp.EXE" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/network_connection/net_connection_win_cmstp_initiated_connection.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: Outbound Network Connection Initiated By Cmstp.EXE",
entity page, dataset version ref-7cfb0dd39f87, updated 2024-05-31T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/efafe0bf-4238-479e-af8f-797bd3490d2d (accessed 2026-11-03).
Underlying source: SigmaHQ rule efafe0bf-4238-479e-af8f-797bd3490d2d, 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.