Potential Execution via XZBackdoor

Last updated 8 days ago on 2025-12-17
Created 2 years ago on 2024-04-01

About

It identifies potential malicious shell executions through remote SSH and detects cases where the sshd service suddenly terminates soon after successful execution, suggesting suspicious behavior similar to the XZ backdoor.
Tags
Domain: EndpointOS: LinuxUse Case: Threat DetectionTactic: Credential AccessTactic: PersistenceTactic: Lateral MovementData Source: Elastic DefendLanguage: eql
Severity
high
Risk Score
73
MITRE ATT&CK™

Persistence (TA0003)(external, opens in a new tab or window)

Credential Access (TA0006)(external, opens in a new tab or window)

Lateral Movement (TA0008)(external, opens in a new tab or window)

License
Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-endpoint.events.network*logs-endpoint.events.process*
Related Integrations

endpoint(external, opens in a new tab or window)

Query
text code block:
sequence by host.id with maxspan=1m [process where host.os.type == "linux" and event.action == "end" and process.name == "sshd" and process.exit_code != 0 and process.command_line == "/usr/sbin/sshd -D -R" and process.parent.command_line == "sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups"] by process.entity_id [process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and process.parent.name == "sshd" and process.parent.command_line == "/usr/sbin/sshd -D -R" and process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and process.args == "-c" and not process.executable in ("/usr/sbin/sshd", "/sbin/unix_chkpwd") and not ( process.args like ("rsync*", "systemctl*", "/usr/sbin/unix_chkpwd", "/usr/bin/google_authorized_keys", "/usr/sbin/aad_certhandler*", "bash -c bash -s", "/usr/lib/ssh/sftp-server", "stat /etc/is_upgrade_install > /dev/null 2>&1", "stat /opt/qradar/ha/.*", "/usr/bin/env -i PATH=*", "/opt/gitlab/embedded/service/gitlab-shell/bin/gitlab-shell key*", "test -e /*", "md5sum*", "check_mk_agent") or process.command_line like ("sh -c /usr/bin/env -i PATH=*", "sh -c -- /usr/bin/env -i PATH=*", "*/root/.ansible/tmp/ansible-tmp*") )] by process.parent.entity_id

Install detection rules in Elastic Security

Detect Potential Execution via XZBackdoor in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).