Potential Fake Instance Of Hxtsr.EXE Executed — Sigma Rule

Rule metadata and linked tags

Author: Sreeman. Source status: test; severity: medium. Source dates: 2020-04-17 / 2024-02-08.

{
  "product": "windows",
  "category": "process_creation"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 63ae5cdd8699568776b47307067799a5d7ccb05851722cd5bbbfb8b04cc6fd42

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Potential Fake Instance Of Hxtsr.EXE Executed
id: 4e762605-34a8-406d-b72e-c1a089313320
status: test
description: |
    HxTsr.exe is a Microsoft compressed executable file called Microsoft Outlook Communications.
    HxTsr.exe is part of Outlook apps, because it resides in a hidden "WindowsApps" subfolder of "C:\Program Files".
    Any instances of hxtsr.exe not in this folder may be malware camouflaging itself as HxTsr.exe
references:
    - Internal Research
author: Sreeman
date: 2020-04-17
modified: 2024-02-08
tags:
    - attack.stealth
    - attack.t1036
logsource:
    product: windows
    category: process_creation
detection:
    # TODO: Link this to the more generic system process rule
    selection:
        Image|endswith: '\hxtsr.exe'
    filter_main_hxtsr:
        Image|contains: ':\program files\windowsapps\microsoft.windowscommunicationsapps_'
        Image|endswith: '\hxtsr.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• Internal Research (source note; no public URL supplied)