Detection rules › Sigma
Potentially Suspicious Windows App Activity
Detects potentially suspicious child process of applications launched from inside the WindowsApps directory. This could be a sign of a rogue ".appx" package installation/execution
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | No specific technique |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
title: Potentially Suspicious Windows App Activity
id: f91ed517-a6ba-471d-9910-b3b4a398c0f3
status: test
description: Detects potentially suspicious child process of applications launched from inside the WindowsApps directory. This could be a sign of a rogue ".appx" package installation/execution
references:
- https://news.sophos.com/en-us/2021/11/11/bazarloader-call-me-back-attack-abuses-windows-10-apps-mechanism/
- https://www.sentinelone.com/labs/inside-malicious-windows-apps-for-malware-deployment/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-12
modified: 2025-10-07
tags:
- attack.stealth
logsource:
product: windows
category: process_creation
detection:
selection_parent:
# GrandParentImage|endswith: '\sihost.exe'
ParentImage|contains: 'C:\Program Files\WindowsApps\'
selection_susp_img:
Image|endswith:
# You can add more LOLBINs
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell.exe'
- '\powershell_ise.exe'
- '\pwsh.exe'
- '\regsvr32.exe'
- '\rundll32.exe'
- '\wscript.exe'
selection_susp_cli:
# You can add more potentially suspicious keywords
CommandLine|contains:
- 'cmd /c'
- 'Invoke-'
- 'Base64'
filter_optional_terminal:
ParentImage|contains: ':\Program Files\WindowsApps\Microsoft.WindowsTerminal'
ParentImage|endswith: '\WindowsTerminal.exe'
# Note: to avoid FP add the default shells and profiles that your WT integrates
Image|endswith:
- '\powershell.exe'
- '\cmd.exe'
- '\pwsh.exe'
filter_optional_sysinternals:
ParentImage|startswith: 'C:\Program Files\WindowsApps\Microsoft.SysinternalsSuite'
Image|endswith: '\cmd.exe'
condition: selection_parent and 1 of selection_susp_* and not 1 of filter_optional_*
falsepositives:
- Legitimate packages that make use of external binaries such as Windows Terminal
level: medium
Stages and Predicates
Stage 0: condition
selection_parent and 1 of selection_susp_* and not 1 of filter_optional_*Stage 1: selection_parent
selection_parent:
ParentImage|contains: 'C:\Program Files\WindowsApps\'
Stage 2: selection_susp_img
selection_susp_img:
Image|endswith:
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell.exe'
- '\powershell_ise.exe'
- '\pwsh.exe'
- '\regsvr32.exe'
- '\rundll32.exe'
- '\wscript.exe'
Stage 3: selection_susp_cli
selection_susp_cli:
CommandLine|contains:
- 'cmd /c'
- 'Invoke-'
- 'Base64'
Stage 4: not filter_optional_*
filter_optional_terminal:
ParentImage|contains: ':\Program Files\WindowsApps\Microsoft.WindowsTerminal'
ParentImage|endswith: '\WindowsTerminal.exe'
Image|endswith:
- '\powershell.exe'
- '\cmd.exe'
- '\pwsh.exe'
filter_optional_sysinternals:
ParentImage|startswith: 'C:\Program Files\WindowsApps\Microsoft.SysinternalsSuite'
Image|endswith: '\cmd.exe'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Image | ends_with | \cmd.exe |
Image | ends_with | \powershell.exe |
Image | ends_with | \pwsh.exe |
ParentImage | ends_with | \WindowsTerminal.exe |
ParentImage | match | :\Program Files\WindowsApps\Microsoft.WindowsTerminal |
Image | ends_with | \cmd.exe |
ParentImage | starts_with | C:\Program Files\WindowsApps\Microsoft.SysinternalsSuite |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|
ParentImage | match |
|