[metadata]
creation_date = "2022/03/07"
maturity = "development"
updated_date = "2022/03/28"

[rule]
author = ["Elastic"]
description = """
Identifies Linux binary expect abuse to break out from restricted environments by spawning an interactive system shell.
The expect utility allows us to automate control of interactive applications such as telnet,ftp,ssh and others and the
activity of spawning shell is not a standard use of this binary for a user or system administrator and could potentially
indicate malicious actor attempting to improve the capabilities or stability of their access.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Linux Restricted Shell Breakout via the expect command"
references = ["https://gtfobins.github.io/gtfobins/expect/"]
risk_score = 47
rule_id = "fd3fc25e-7c7c-4613-8209-97942ac609f6"
severity = "medium"
tags = ["Elastic", "Host", "Linux", "Threat Detection", "Execution", "GTFOBins"]
timestamp_override = "event.ingested"
type = "eql"

query = '''
sequence by host.id, process.pid with maxspan=1m 
[process where process.name == "expect" and process.args : "-c" and process.args : ("spawn /bin/sh;interact", "spawn /bin/bash;interact", "spawn /bin/dash;interact", "spawn sh;interact","spawn bash;interact", "spawn dash;interact")] 
[process where process.parent.name == "expect" and process.name : ("bash", "sh", "dash")]
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[rule.threat.technique.subtechnique]]
id = "T1059.004"
name = "Unix Shell"
reference = "https://attack.mitre.org/techniques/T1059/004/"



[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"