Detection rules › Sigma

Potential DLL Sideloading Of DbgModel.DLL

Status
test
Severity
medium
Log source
category image_load, product windows
Author
Gary Lobermier
Source
github.com/SigmaHQ/sigma

Detects potential DLL sideloading of "DbgModel.dll"

Known false positives

  • Legitimate applications loading their own versions of the DLL mentioned in this rule

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 7: Image loaded

Rule body

title: Potential DLL Sideloading Of DbgModel.DLL
id: fef394cd-f44d-4040-9b18-95d92fe278c0
status: test
description: Detects potential DLL sideloading of "DbgModel.dll"
references:
    - https://hijacklibs.net/entries/microsoft/built-in/dbgmodel.html
author: Gary Lobermier
date: 2024-07-11
modified: 2024-07-22
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    category: image_load
detection:
    selection:
        ImageLoaded|endswith: '\dbgmodel.dll'
    filter_main_generic:
        ImageLoaded|startswith:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
            - 'C:\Windows\WinSxS\'
    filter_optional_windbg:
        ImageLoaded|startswith: 'C:\Program Files\WindowsApps\Microsoft.WinDbg_'
    filter_optional_windows_kits:
        ImageLoaded|startswith:
            - 'C:\Program Files (x86)\Windows Kits\'
            - 'C:\Program Files\Windows Kits\'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Legitimate applications loading their own versions of the DLL mentioned in this rule
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: selection

selection:
    ImageLoaded|endswith: '\dbgmodel.dll'

Stage 2: not filter_main_generic

filter_main_generic:
    ImageLoaded|startswith:
        - 'C:\Windows\System32\'
        - 'C:\Windows\SysWOW64\'
        - 'C:\Windows\WinSxS\'

Stage 3: not filter_optional_*

filter_optional_windbg:
    ImageLoaded|startswith: 'C:\Program Files\WindowsApps\Microsoft.WinDbg_'
filter_optional_windows_kits:
    ImageLoaded|startswith:
        - 'C:\Program Files (x86)\Windows Kits\'
        - 'C:\Program Files\Windows Kits\'

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
ImageLoadedstarts_withC:\Windows\SysWOW64\excludes:ImageLoaded field:"ImageLoaded" value:"C:\Windows\SysWOW64\"
ImageLoadedstarts_withC:\Windows\System32\excludes:ImageLoaded field:"ImageLoaded" value:"C:\Windows\System32\"
ImageLoadedstarts_withC:\Windows\WinSxS\excludes:ImageLoaded field:"ImageLoaded" value:"C:\Windows\WinSxS\"
ImageLoadedstarts_withC:\Program Files (x86)\Windows Kits\excludes:ImageLoaded field:"ImageLoaded" value:"C:\Program Files (x86)\Windows Kits\"
ImageLoadedstarts_withC:\Program Files\Windows Kits\excludes:ImageLoaded field:"ImageLoaded" value:"C:\Program Files\Windows Kits\"
ImageLoadedstarts_withC:\Program Files\WindowsApps\Microsoft.WinDbg_excludes:ImageLoaded field:"ImageLoaded" value:"C:\Program Files\WindowsApps\Microsoft.WinDbg_"

Indicators

These rows show field, operator, and value matches.