Suspicious Screensaver Binary File Creation

Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension

Sigma rule (View on GitHub)

 1title: Suspicious Screensaver Binary File Creation
 2id: 97aa2e88-555c-450d-85a6-229bcd87efb8
 3status: test
 4description: |
 5    Adversaries may establish persistence by executing malicious content triggered by user inactivity.
 6    Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension    
 7references:
 8    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.002/T1546.002.md
 9author: frack113
10date: 2021/12/29
11modified: 2022/11/08
12tags:
13    - attack.persistence
14    - attack.t1546.002
15logsource:
16    product: windows
17    category: file_event
18detection:
19    selection:
20        TargetFilename|endswith: '.scr'
21    filter_generic:
22        Image|endswith:
23            - '\Kindle.exe'
24            - '\Bin\ccSvcHst.exe' # Symantec Endpoint Protection
25    filter_tiworker:
26        # ParentCommandLine: C:\WINDOWS\system32\svchost.exe -k DcomLaunch -p
27        Image|endswith: '\TiWorker.exe'
28        TargetFilename|endswith: '\uwfservicingscr.scr'
29    condition: selection and not 1 of filter_*
30falsepositives:
31    - Unknown
32level: medium

References

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