Network Connection Initiated Via Notepad.EXE

Hunt Hypothesis

Detects a network connection that is initiated by the “notepad.exe” process. This might be a sign of process injection from a beacon process or something similar. Notepad rarely initiates a network co

Detection Rule

Sigma (Original)

title: Network Connection Initiated Via Notepad.EXE
id: e81528db-fc02-45e8-8e98-4e84aba1f10b
status: test
description: |
    Detects a network connection that is initiated by the "notepad.exe" process.
    This might be a sign of process injection from a beacon process or something similar.
    Notepad rarely initiates a network communication except when printing documents for example.
references:
    - https://web.archive.org/web/20200219102749/https://www.sans.org/cyber-security-summit/archives/file/summit-archive-1492186586.pdf
    - https://www.cobaltstrike.com/blog/why-is-notepad-exe-connecting-to-the-internet
author: EagleEye Team
date: 2020-05-14
modified: 2024-02-02
tags:
    - attack.privilege-escalation
    - attack.command-and-control
    - attack.execution
    - attack.stealth
    - attack.t1055
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\notepad.exe'
    filter_optional_printing:
        DestinationPort: 9100
    condition: selection and not 1 of filter_optional_*
falsepositives:
    - Printing documents via notepad might cause communication with the printer via port 9100 or similar.
level: high

KQL (Azure Sentinel)

imNetworkSession
| where (SrcProcessName endswith "\\notepad.exe" or DstProcessName endswith "\\notepad.exe") and (not(DstPortNumber == 9100))

Required Data Sources

Sentinel Table	Notes
`imNetworkSession`	Ensure this data connector is enabled

False Positive Guidance

Printing documents via notepad might cause communication with the printer via port 9100 or similar.

MITRE ATT&CK Context

Tactic: Privilege Escalation
Tactic: Command and Control
Tactic: Execution
Technique: T1055 — T1055