Suspicious Path In Keyboard Layout IME File Registry Value

Severity: high
Author: X__Junior (Nextron Systems)
Source: upstream

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.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.001` Impair Defenses: Disable or Modify Tools

Event coverage

Provider	Event ID	Title
Sysmon	13	RegistryEvent (Value Set)

Stages and Predicates

Stage 1: `selection_registry`

TargetObject|contains: 'Ime File'
TargetObject|contains: '\Control\Keyboard Layouts\'

Stage 2: `1 of selection_folders_1`

or:
Details|contains: ':\Perflogs\'
Details|contains: ':\Users\Public\'
Details|contains: ':\Windows\Temp\'
Details|contains: '\AppData\Local\Temp\'
Details|contains: '\AppData\Roaming\'
Details|contains: '\Temporary Internet'

Stage 3: `1 of selection_folders_2`

or:
Details|contains: ':\Users\'
Details|contains: '\Contacts\'
Details|contains: ':\Users\'
Details|contains: '\Favorites\'
Details|contains: ':\Users\'
Details|contains: '\Favourites\'

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.

Field	Kind	Values
`Details`	match	`:\Perflogs\` corpus 3 (sigma 3) `:\Users\` corpus 4 (sigma 4) `:\Users\Public\` corpus 4 (sigma 4) `:\Windows\Temp\` corpus 4 (sigma 4) `\AppData\Local\Temp\` corpus 9 (sigma 9) `\AppData\Roaming\` corpus 2 (sigma 2) `\Contacts\` corpus 4 (sigma 4) `\Favorites\` corpus 3 (sigma 3) `\Favourites\` corpus 3 (sigma 3) `\Temporary Internet` corpus 3 (sigma 3)
`TargetObject`	match	`Ime File` corpus 2 (sigma 2) `\Control\Keyboard Layouts\` corpus 2 (sigma 2)