Uncommon Extension In Keyboard Layout IME File Registry Value

Hunt Hypothesis

Detects usage of Windows Input Method Editor (IME) keyboard layout feature, which allows an attacker to load a DLL into the process after sending the WM_INPUTLANGCHANGEREQUEST message. Before doing th

Detection Rule

Sigma (Original)

title: Uncommon Extension In Keyboard Layout IME File Registry Value
id: b888e3f2-224d-4435-b00b-9dd66e9ea1f1
related:
    - id: 9d8f9bb8-01af-4e15-a3a2-349071530530
      type: derived
status: test
description: |
    Detects usage of Windows Input Method Editor (IME) keyboard layout feature, which allows an attacker to load a DLL into the process after sending the WM_INPUTLANGCHANGEREQUEST message.
    Before doing this, the client needs to register the DLL in a special registry key that is assumed to implement this keyboard layout. This registry key should store a value named "Ime File" with a DLL path.
    IMEs are essential for languages that have more characters than can be represented on a standard keyboard, such as Chinese, Japanese, and Korean.
references:
    - https://www.linkedin.com/pulse/guntior-story-advanced-bootkit-doesnt-rely-windows-disk-baranov-wue8e/
author: X__Junior (Nextron Systems)
date: 2023-11-21
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|contains|all:
            - '\Control\Keyboard Layouts\'
            - 'Ime File'
    filter_main_known_extension:
        Details|endswith: '.ime'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - IMEs are essential for languages that have more characters than can be represented on a standard keyboard, such as Chinese, Japanese, and Korean.
level: high

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey endswith "\\Control\\Keyboard Layouts*" and RegistryKey contains "Ime File") and (not(RegistryValueData endswith ".ime"))

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where (RegistryKey endswith "\\Control\\Keyboard Layouts*" and RegistryKey contains "Ime File") and (not(RegistryValueData endswith ".ime"))

Required Data Sources

False Positive Guidance

• IMEs are essential for languages that have more characters than can be represented on a standard keyboard, such as Chinese, Japanese, and Korean.

MITRE ATT&CK Context

• Technique: T1685 — T1685

References

• https://www.linkedin.com/pulse/guntior-story-advanced-bootkit-doesnt-rely-windows-disk-baranov-wue8e/
• SigmaHQ Rule