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Elastic Docs ›Elastic Security Solution [8.16] ›Detections and alerts ›Prebuilt rule reference

Masquerading Space After Filename

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Masquerading Space After Filename

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This rules identifies a process created from an executable with a space appended to the end of the filename. This may indicate an attempt to masquerade a malicious file as benign to gain user execution. When a space is added to the end of certain files, the OS will execute the file according to it’s true filetype instead of it’s extension. Adversaries can hide a program’s true filetype by changing the extension of the file. They can then add a space to the end of the name so that the OS automatically executes the file when it’s double-clicked.

Rule type: eql

Rule indices:

  • auditbeat-*
  • logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Linux
  • macOS
  • Threat Detection
  • Defense Evasion

Version: 1

Added (Elastic Stack release): 8.6.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query
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process where host.os.type:("linux","macos") and event.type ==
"start" and (process.executable regex~ """/[a-z0-9\s_\-\\./]+\s""")
and not process.name in ("ls", "find", "grep", "xkbcomp")











Threat mapping
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Framework: MITRE ATT&CKTM
















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