Potential OpenSSH Backdoor Logging Activity
editPotential OpenSSH Backdoor Logging Activity
editIdentifies 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: 100 (version history)
Added (Elastic Stack release): 7.12.0
Last modified (Elastic Stack release): 8.5.0
Rule authors: Elastic
Rule license: Elastic License v2
Potential false positives
editUpdates to approved and trusted SSH executables can trigger this rule.
Investigation guide
editRule query
editfile 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" ) )
Threat mapping
editFramework: MITRE ATT&CKTM
-
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/
Rule version history
edit- Version 100 (8.5.0 release)
-
- Formatting only
- Version 4 (8.4.0 release)
-
-
Updated query, changed from:
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" ) )
-
- Version 2 (8.2.0 release)
-
- Formatting only