CodePage Modification Via MODE.COM To Russian Language

calendar Jan 22, 2024 · attack.defense_evasion attack.t1036  ·
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Detects a CodePage modification using the "mode.com" utility to Russian language. This behavior has been used by threat actors behind Dharma ransomware.

Sigma rule (View on GitHub)

 1title: CodePage Modification Via MODE.COM To Russian Language
 2id: 12fbff88-16b5-4b42-9754-cd001a789fb3
 3related:
 4    - id: d48c5ffa-3b02-4c0f-9a9e-3c275650dd0e
 5      type: derived
 6status: experimental
 7description: |
 8    Detects a CodePage modification using the "mode.com" utility to Russian language.
 9    This behavior has been used by threat actors behind Dharma ransomware.    
10references:
11    - https://learn.microsoft.com/en-us/windows/win32/intl/code-page-identifiers
12    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/mode
13    - https://strontic.github.io/xcyclopedia/library/mode.com-59D1ED51ACB8C3D50F1306FD75F20E99.html
14    - https://www.virustotal.com/gui/file/5e75ef02517afd6e8ba6462b19217dc4a5a574abb33d10eb0f2bab49d8d48c22/behavior
15author: Joseliyo Sanchez, @Joseliyo_Jstnk
16date: 2024/01/17
17tags:
18    - attack.defense_evasion
19    - attack.t1036
20logsource:
21    category: process_creation
22    product: windows
23detection:
24    # VT Query: behavior:"mode con cp select=1251"
25    # VT Query: behavior:"mode con cp select=866"
26    selection_img:
27        - Image|endswith: '\mode.com'
28        - OriginalFileName: 'MODE.COM'
29    selection_cli:
30        CommandLine|contains|all:
31            - ' con '
32            - ' cp '
33            - ' select='
34        CommandLine|endswith:
35            - '=1251' # ANSI Cyrillic; Cyrillic (Windows) - Observed ITW by Dharma ransomware
36            - '=866' # OEM Russian; Cyrillic (DOS) - Observed ITW by other malware
37    condition: all of selection_*
38falsepositives:
39    - Russian speaking people changing the CodePage
40level: medium

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