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Elastic Docs ›Elastic Security Solution [8.1] ›Detections and alerts ›Prebuilt rule reference

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: 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
  • Threat Detection
  • Persistence
  • Credential Access

Version: 1

Added (Elastic Stack release): 7.12.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Updates to approved and trusted SSH executables can trigger this rule.

Rule query

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file where event.type == "change" and process.executable :
("/usr/sbin/sshd", "/usr/bin/ssh") and ( file.name : (".*",
"~*") 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" ) )

Threat mapping

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Framework: MITRE ATT&CKTM

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