Potential OpenSSH Backdoor Logging Activity

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.*
endgame-*

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
Elastic Endgame

Version: 102

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

Rule query

edit

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&CK^TM

Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: Modify Authentication Process
- ID: T1556
- Reference URL: https://attack.mitre.org/techniques/T1556/
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Compromise Client Software Binary
- ID: T1554
- Reference URL: https://attack.mitre.org/techniques/T1554/

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