Potential Application Whitelisting Bypass via Dnx.EXE

Hunt Hypothesis

Detects the execution of Dnx.EXE. The Dnx utility allows for the execution of C# code. Attackers might abuse this in order to bypass application whitelisting.

Detection Rule

Sigma (Original)

title: Potential Application Whitelisting Bypass via Dnx.EXE
id: 81ebd28b-9607-4478-bf06-974ed9d53ed7
status: test
description: |
    Detects the execution of Dnx.EXE. The Dnx utility allows for the execution of C# code.
    Attackers might abuse this in order to bypass application whitelisting.
references:
    - https://lolbas-project.github.io/lolbas/OtherMSBinaries/Csi/
    - https://enigma0x3.net/2016/11/17/bypassing-application-whitelisting-by-using-dnx-exe/
author: Beyu Denis, oscd.community
date: 2019-10-26
modified: 2024-04-24
tags:
    - attack.stealth
    - attack.t1218
    - attack.t1027.004
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\dnx.exe'
    condition: selection
falsepositives:
    - Legitimate use of dnx.exe by legitimate user
level: medium

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessName endswith "\\dnx.exe"

Required Data Sources

False Positive Guidance

• Legitimate use of dnx.exe by legitimate user

MITRE ATT&CK Context

• Technique: T1218 — T1218
• Technique: T1027.004 — T1027.004

References

• https://lolbas-project.github.io/lolbas/OtherMSBinaries/Csi/
• https://enigma0x3.net/2016/11/17/bypassing-application-whitelisting-by-using-dnx-exe/
• SigmaHQ Rule