Use Short Name Path in Image

calendar Feb 1, 2024 · attack.defense_evasion attack.t1564.004  ·
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Detect use of the Windows 8.3 short name. Which could be used as a method to avoid Image detection

Sigma rule (View on GitHub)

 1title: Use Short Name Path in Image
 2id: a96970af-f126-420d-90e1-d37bf25e50e1
 3related:
 4    - id: 349d891d-fef0-4fe4-bc53-eee623a15969
 5      type: similar
 6status: test
 7description: Detect use of the Windows 8.3 short name. Which could be used as a method to avoid Image detection
 8references:
 9    - https://www.acunetix.com/blog/articles/windows-short-8-3-filenames-web-security-problem/
10    - https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/cc959352(v=technet.10)?redirectedfrom=MSDN
11    - https://twitter.com/frack113/status/1555830623633375232
12author: frack113, Nasreddine Bencherchali
13date: 2022/08/07
14modified: 2023/03/21
15tags:
16    - attack.defense_evasion
17    - attack.t1564.004
18logsource:
19    category: process_creation
20    product: windows
21detection:
22    selection:
23        Image|contains:
24            - '~1\'
25            - '~2\'
26    filter1:
27        - ParentImage:
28              - C:\Windows\System32\Dism.exe
29              - C:\Windows\System32\cleanmgr.exe  # Spawns DismHost.exe with a shortened username (if too long)
30        - ParentImage|endswith:
31              - '\WebEx\WebexHost.exe'  # Spawns a shortened version of the CLI and Image processes
32              - '\thor\thor64.exe'
33        - Product: 'InstallShield (R)'
34        - Description: 'InstallShield (R) Setup Engine'
35        - Company: 'InstallShield Software Corporation'
36    filter_installers:
37        - Image|contains|all:
38              - '\AppData\'
39              - '\Temp\'
40        - Image|endswith:
41              - '~1\unzip.exe'
42              - '~1\7zG.exe'
43    condition: selection and not 1 of filter*
44falsepositives:
45    - Applications could use this notation occasionally which might generate some false positives. In that case Investigate the parent and child process.
46level: medium

References

  • Windows Short (8.3) Filenames - A Security Nightmare? | Acunetix

    Each time you create a new file on Windows, the operating system also generates an MS-DOS-compatible short file name in 8.3 format, to allow MS-DOS-based or 16-bit Windows-based programs to access files which have a long name. You can see these MS-DOS-compatible short file names by...Read more


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  • NtfsDisable8dot3NameCreation

    NtfsDisable8dot3NameCreation Article 03/04/2010 HKLM\SYSTEM\CurrentControlSet\Control\FileSystem Description Determines whether NTFS generates a short name in the 8.3 naming convention for long fil...


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  • Something went wrong, but don’t fret — let’s give it another shot.


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