Sigma rule: Office Application Initiated Network Connection Over Uncommon Ports

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-32dad557036f, updated 2025-10-17T00:00:00.000Z.

Rule

Title
Office Application Initiated Network Connection Over Uncommon Ports
Status
test
Level
medium
Author
X__Junior (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Date
2023-07-12
Modified
2025-10-17
File
rules/windows/network_connection/net_connection_win_office_uncommon_ports.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects an office suit application (Word, Excel, PowerPoint, Outlook) communicating to target systems over uncommon ports.

Log source

product
windows
category
network_connection

Detection

selection:
    Initiated: 'true'
    Image|endswith:
        - '\excel.exe'
        - '\outlook.exe'
        - '\powerpnt.exe'
        - '\winword.exe'
        - '\wordview.exe'
filter_main_common_ports:
    DestinationPort:
        - 53 # DNS
        - 80 # HTTP
        - 139 # NETBIOS
        - 389 # LDAP
        - 443 # HTTPS
        - 445 # SMB
        - 3268 # MSFT-GC
filter_main_outlook_ports:
    Image|contains: ':\Program Files\Microsoft Office\'
    Image|endswith: '\OUTLOOK.EXE'
    DestinationPort:
        - 143
        - 465 # SMTP
        - 587 # SMTP
        - 993 # IMAP
        - 995 # POP3
condition: selection and not 1 of filter_main_*

False positives (as the rule lists them)

  • Other ports can be used, apply additional filters accordingly

Tags

  • attack.command-and-control
  • attack.stealth

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_office_uncommon_ports.yml

Sources and licences

  • SigmaHQ

    "Office Application Initiated Network Connection Over Uncommon Ports" by X__Junior (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/network_connection/net_connection_win_office_uncommon_ports.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: Office Application Initiated Network Connection Over Uncommon Ports",
entity page, dataset version ref-32dad557036f, updated 2025-10-17T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/3b5ba899-9842-4bc2-acc2-12308498bf42 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 3b5ba899-9842-4bc2-acc2-12308498bf42, 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.