Roshal Archive (RAR) or PowerShell File Downloaded from the Internet

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Roshal Archive (RAR) or PowerShell File Downloaded from the Internet

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Detects a Roshal Archive (RAR) file or PowerShell script downloaded from the internet by an internal host. Gaining initial access to a system and then downloading encoded or encrypted tools to move laterally is a common practice for adversaries as a way to protect their more valuable tools and tactics, techniques, and procedures (TTPs). This may be atypical behavior for a managed network and can be indicative of malware, exfiltration, or command and control.

Rule type: query

Rule indices:

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

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Network
  • Threat Detection
  • Command and Control
  • Host

Version: 9

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## Threat intel

This activity has been observed in FIN7 campaigns.

Rule query

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event.category:(network or network_traffic) and network.protocol:http and
  (url.extension:(ps1 or rar) or url.path:(*.ps1 or *.rar)) and
    not destination.ip:(
      10.0.0.0/8 or
      127.0.0.0/8 or
      169.254.0.0/16 or
      172.16.0.0/12 or
      192.0.0.0/24 or
      192.0.0.0/29 or
      192.0.0.8/32 or
      192.0.0.9/32 or
      192.0.0.10/32 or
      192.0.0.170/32 or
      192.0.0.171/32 or
      192.0.2.0/24 or
      192.31.196.0/24 or
      192.52.193.0/24 or
      192.168.0.0/16 or
      192.88.99.0/24 or
      224.0.0.0/4 or
      100.64.0.0/10 or
      192.175.48.0/24 or
      198.18.0.0/15 or
      198.51.100.0/24 or
      203.0.113.0/24 or
      240.0.0.0/4 or
      "::1" or
      "FE80::/10" or
      "FF00::/8"
    ) and
    source.ip:(
      10.0.0.0/8 or
      172.16.0.0/12 or
      192.168.0.0/16
    )

Framework: MITRE ATT&CKTM