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Detection rules › Sigma

UAC Bypass With Fake DLL

Status
test
Severity
high
Log source
product windows, category image_load
Author
oscd.community, Dmitry Uchakin
Source
github.com/SigmaHQ/sigma

Attempts to load dismcore.dll after dropping it

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1574.001 Hijack Execution Flow: DLL
Privilege EscalationT1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control
StealthT1574.001 Hijack Execution Flow: DLL

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: UAC Bypass With Fake DLL
id: a5ea83a7-05a5-44c1-be2e-addccbbd8c03
status: test
description: Attempts to load dismcore.dll after dropping it
references:
    - https://steemit.com/utopian-io/@ah101/uac-bypassing-utility
author: oscd.community, Dmitry Uchakin
date: 2020-10-06
modified: 2022-12-25
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
    - attack.stealth
    - attack.t1548.002
    - attack.t1574.001
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith: '\dism.exe'
        ImageLoaded|endswith: '\dismcore.dll'
    filter:
        ImageLoaded: 'C:\Windows\System32\Dism\dismcore.dll'
    condition: selection and not filter
falsepositives:
    - Actions of a legitimate telnet client
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    Image|endswith: '\dism.exe'
    ImageLoaded|endswith: '\dismcore.dll'

Stage 2: not filter

filter:
    ImageLoaded: 'C:\Windows\System32\Dism\dismcore.dll'

Exclusions

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

FieldKindExcluded values
ImageLoadedeqC:\Windows\System32\Dism\dismcore.dll

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
Imageends_with
  • \dism.exe corpus 6 (sigma 6)
ImageLoadedends_with
  • \dismcore.dll corpus 2 (sigma 2)