Suspicious Network Connection Attempt by Rootedit
Identifies an outbound network connection attempt followed by a session id change as the root user by the same process entity. This particular instantiation of a network connection is abnormal and should be investigated as it may indicate a potential reverse shell activity via a privileged process.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
Severity: medium
Risk score: 43
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
- Command and Control
Version: 3 (version history)
Added (Elastic Stack release): 8.3.0
Last modified (Elastic Stack release): 8.4.0
Rule authors: Elastic
Rule license: Elastic License v2
Potential false positivesedit
False-Positives (FP) can appear if another remote terminal service is being used to connect to it’s listener but typically SSH is used in these scenarios.
Investigation guideedit
## Triage and analysis ### Investigating Connection Attempt by Non-SSH Root Session Detection alerts from this rule indicate a strange or abnormal outbound connection attempt by a privileged process. Here are some possible avenues of investigation: - Examine unusual and active sessions using commands such as 'last -a', 'netstat -a', and 'w -a'. - Analyze processes and command line arguments to detect anomalous process execution that may be acting as a listener. - Analyze anomalies in the use of files that do not normally initiate connections. - Examine processes utilizing the network that do not normally have network communication.
Rule queryedit
sequence by process.entity_id with maxspan=1m [network where
event.type == "start" and event.action == "connection_attempted" and
user.id == "0" and not process.executable : ("/bin/ssh",
"/sbin/ssh", "/usr/lib/systemd/systemd", "/usr/sbin/sshd")] [process
where event.action == "session_id_change" and user.id == "0" and
not process.executable : ("/bin/ssh", "/sbin/ssh",
"/usr/lib/systemd/systemd", "/usr/sbin/sshd")]
Threat mappingedit
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
-
Technique:
- Name: Non-Application Layer Protocol
- ID: T1095
- Reference URL: https://attack.mitre.org/techniques/T1095/
-
Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
-
Technique:
- Name: Abuse Elevation Control Mechanism
- ID: T1548
- Reference URL: https://attack.mitre.org/techniques/T1548/
Rule version historyedit
- Version 3 (8.4.0 release)
-
-
Updated query, changed from:
sequence by process.entity_id with maxspan=1m [network where event.type == "start" and event.action == "connection_attempted" and user.id == "0" and not process.executable : ("/bin/ssh", "/sbin/ssh", "/usr/lib/systemd/systemd")] [process where event.action == "session_id_change" and user.id == "0"]
-