CVE-2021-31979 CVE-2021-33771 Exploits by Sourgum

Description

Detects patterns as noticed in exploitation of Windows CVE-2021-31979 CVE-2021-33771 vulnerability and DevilsTongue malware by threat group Sourgum

Query · sigma

selection:
  TargetFilename|contains:
  - C:\Windows\system32\physmem.sys
  - C:\Windows\System32\IME\IMEJP\imjpueact.dll
  - C:\Windows\system32\ime\IMETC\IMTCPROT.DLL
  - C:\Windows\system32\ime\SHARED\imecpmeid.dll
  - C:\Windows\system32\config\spp\ServiceState\Recovery\pac.dat
  - C:\Windows\system32\config\cy-GB\Setup\SKB\InputMethod\TupTask.dat
  - C:\Windows\system32\config\config\startwus.dat
  - C:\Windows\system32\ime\SHARED\WimBootConfigurations.ini
  - C:\Windows\system32\ime\IMEJP\WimBootConfigurations.ini
  - C:\Windows\system32\ime\IMETC\WimBootConfigurations.ini
condition: selection

Known false positives

  • Unlikely
Raw source CVE-2021-31979 CVE-2021-33771 Exploits by Sourgum · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: CVE-2021-31979 CVE-2021-33771 Exploits by Sourgum
id: ad7085ac-92e4-4b76-8ce2-276d2c0e68ef
status: test
description: Detects patterns as noticed in exploitation of Windows CVE-2021-31979 CVE-2021-33771 vulnerability and DevilsTongue malware by threat group Sourgum
references:
    - https://www.microsoft.com/security/blog/2021/07/15/protecting-customers-from-a-private-sector-offensive-actor-using-0-day-exploits-and-devilstongue-malware/
    - https://citizenlab.ca/2021/07/hooking-candiru-another-mercenary-spyware-vendor-comes-into-focus/
author: Sittikorn S
date: 2021-07-16
modified: 2022-10-09
tags:
    - attack.initial-access
    - attack.execution
    - attack.credential-access
    - attack.t1566
    - attack.t1203
    - cve.2021-33771
    - cve.2021-31979
    - detection.emerging-threats
    # - threat_group.Sourgum
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|contains:
            - 'C:\Windows\system32\physmem.sys'
            - 'C:\Windows\System32\IME\IMEJP\imjpueact.dll'
            - 'C:\Windows\system32\ime\IMETC\IMTCPROT.DLL'
            - 'C:\Windows\system32\ime\SHARED\imecpmeid.dll'
            - 'C:\Windows\system32\config\spp\ServiceState\Recovery\pac.dat'
            - 'C:\Windows\system32\config\cy-GB\Setup\SKB\InputMethod\TupTask.dat'
            - 'C:\Windows\system32\config\config\startwus.dat'
            - 'C:\Windows\system32\ime\SHARED\WimBootConfigurations.ini'
            - 'C:\Windows\system32\ime\IMEJP\WimBootConfigurations.ini'
            - 'C:\Windows\system32\ime\IMETC\WimBootConfigurations.ini'
    condition: selection
falsepositives:
    - Unlikely
level: critical

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