Remote File Download Via Findstr.EXE

calendar Nov 15, 2023 · attack.defense_evasion attack.t1218 attack.t1564.004 attack.t1552.001 attack.t1105  ·
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Detects execution of "findstr" with specific flags and a remote share path. This specific set of CLI flags would allow "findstr" to download the content of the file located on the remote share as described in the LOLBAS entry.

Sigma rule (View on GitHub)

 1title: Remote File Download Via Findstr.EXE
 2id: 587254ee-a24b-4335-b3cd-065c0f1f4baa
 3related:
 4    - id: bf6c39fc-e203-45b9-9538-05397c1b4f3f
 5      type: obsoletes
 6status: experimental
 7description: |
 8        Detects execution of "findstr" with specific flags and a remote share path. This specific set of CLI flags would allow "findstr" to download the content of the file located on the remote share as described in the LOLBAS entry.
 9references:
10    - https://lolbas-project.github.io/lolbas/Binaries/Findstr/
11    - https://oddvar.moe/2018/04/11/putting-data-in-alternate-data-streams-and-how-to-execute-it-part-2/
12    - https://gist.github.com/api0cradle/cdd2d0d0ec9abb686f0e89306e277b8f
13author: Furkan CALISKAN, @caliskanfurkan_, @oscd_initiative, Nasreddine Bencherchali (Nextron Systems)
14date: 2020/10/05
15modified: 2023/11/12
16tags:
17    - attack.defense_evasion
18    - attack.t1218
19    - attack.t1564.004
20    - attack.t1552.001
21    - attack.t1105
22logsource:
23    category: process_creation
24    product: windows
25detection:
26    selection_findstr:
27        - CommandLine|contains: findstr
28        - Image|endswith: 'findstr.exe'
29        - OriginalFileName: 'FINDSTR.EXE'
30    selection_cli_download_1:
31        CommandLine|contains:
32            - ' /v '
33            - ' -v '
34    selection_cli_download_2:
35        CommandLine|contains:
36            - ' /l '
37            - ' -l '
38    selection_cli_download_3:
39        CommandLine|contains: '\\\\'
40    condition: selection_findstr and all of selection_cli_download_*
41falsepositives:
42    - Unknown
43level: medium

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