Detection rules › Sigma

Potential appverifUI.DLL Sideloading

Status
test
Severity
high
Log source
product windows, category image_load
Author
X__Junior (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects potential DLL sideloading of "appverifUI.dll"

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: Potential appverifUI.DLL Sideloading
id: ee6cea48-c5b6-4304-a332-10fc6446f484
status: test
description: Detects potential DLL sideloading of "appverifUI.dll"
references:
    - https://web.archive.org/web/20220519091349/https://fatrodzianko.com/2020/02/15/dll-side-loading-appverif-exe/
author: X__Junior (Nextron Systems)
date: 2023-06-20
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    category: image_load
    product: windows
detection:
    selection:
        ImageLoaded|endswith: '\appverifUI.dll'
    filter_main_legit_path:
        Image:
            - 'C:\Windows\SysWOW64\appverif.exe'
            - 'C:\Windows\System32\appverif.exe'
        ImageLoaded|startswith:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
            - 'C:\Windows\WinSxS\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

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

Stage 2: not filter_main_legit_path

filter_main_legit_path:
    Image:
        - 'C:\Windows\SysWOW64\appverif.exe'
        - 'C:\Windows\System32\appverif.exe'
    ImageLoaded|startswith:
        - 'C:\Windows\System32\'
        - 'C:\Windows\SysWOW64\'
        - 'C:\Windows\WinSxS\'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
ImageeqC:\Windows\SysWOW64\appverif.exe
ImageeqC:\Windows\System32\appverif.exe
ImageLoadedstarts_withC:\Windows\SysWOW64\
ImageLoadedstarts_withC:\Windows\System32\
ImageLoadedstarts_withC:\Windows\WinSxS\

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.

FieldKindValues
ImageLoadedends_with
  • \appverifUI.dll