Potential OpenSSH Backdoor Logging Activity

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Potential OpenSSH Backdoor Logging Activity

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Identifies a Secure Shell (SSH) client or server process creating or writing to a known SSH backdoor log file. Adversaries may modify SSH related binaries for persistence or credential access via patching sensitive functions to enable unauthorized access or to log SSH credentials for exfiltration.

Rule type: eql

Rule indices:

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

Severity: high

Risk score: 73

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
  • Host
  • Linux
  • Threat Detection
  • Persistence
  • Credential Access

Version: 101

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query

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file where event.type == "change" and process.executable : ("/usr/sbin/sshd", "/usr/bin/ssh") and
  (
    (file.name : (".*", "~*", "*~") and not file.name : (".cache", ".viminfo", ".bash_history")) or
    file.extension : ("in", "out", "ini", "h", "gz", "so", "sock", "sync", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9") or
    file.path :
    (
      "/private/etc/*--",
      "/usr/share/*",
      "/usr/include/*",
      "/usr/local/include/*",
      "/private/tmp/*",
      "/private/var/tmp/*",
      "/usr/tmp/*",
      "/usr/share/man/*",
      "/usr/local/share/*",
      "/usr/lib/*.so.*",
      "/private/etc/ssh/.sshd_auth",
      "/usr/bin/ssd",
      "/private/var/opt/power",
      "/private/etc/ssh/ssh_known_hosts",
      "/private/var/html/lol",
      "/private/var/log/utmp",
      "/private/var/lib",
      "/var/run/sshd/sshd.pid",
      "/var/run/nscd/ns.pid",
      "/var/run/udev/ud.pid",
      "/var/run/udevd.pid"
    )
  )

Framework: MITRE ATT&CKTM