From d4c426a0221ed1b57c9b23e2f41bfca63b4dab04 Mon Sep 17 00:00:00 2001
From: shashank-elastic <91139415+shashank-elastic@users.noreply.github.com>
Date: Mon, 21 Mar 2022 22:46:53 +0530
Subject: [PATCH] [New Rule] cpulimit shell evasion threat (#1851)

* cpulimit shell evasion threat

* Update rules/linux/execution_cpulimit_binary.toml

Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>

* Update rules/linux/execution_cpulimit_binary.toml

Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>

Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>

(cherry picked from commit 2ab5a1f44af75c1cb7ac7db26dfa804957500483)
---
 rules/linux/execution_cpulimit_binary.toml | 52 ++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 rules/linux/execution_cpulimit_binary.toml

diff --git a/rules/linux/execution_cpulimit_binary.toml b/rules/linux/execution_cpulimit_binary.toml
new file mode 100644
index 000000000..4e47d5086
--- /dev/null
+++ b/rules/linux/execution_cpulimit_binary.toml
@@ -0,0 +1,52 @@
+[metadata]
+creation_date = "2022/03/17"
+maturity = "production"
+updated_date = "2022/03/17"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies Linux binary cpulimit abuse to break out from restricted environments by spawning an interactive system
+shell. The cpulimit utility is used to restrict the CPU usage of a process in cases of CPU or system load exceeding the
+defined threshold and the activity of spawning a shell is not a standard use of this binary by a user or system
+administrator. This can potentially indicate a 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 cpulimit Shell Evasion"
+references = ["https://gtfobins.github.io/gtfobins/cpulimit/"]
+risk_score = 47
+rule_id = "0968cfbd-40f0-4b1c-b7b1-a60736c7b241"
+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 event.type == "start" and process.name == "cpulimit" and process.args == "-f" and process.args : ("/bin/sh", "/bin/bash", "/bin/dash", "sh", "bash", "dash")]
+[process where process.parent.name == "cpulimit" 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/"
+