Linux Shell Evasion Rule Tuning (#1878)

* Linux Shell Evasion Rule Tuning * Update execution_python_tty_shell.toml * Update rules/linux/execution_apt_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_apt_binary.toml * Update rules/linux/execution_awk_binary_shell.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_awk_binary_shell.toml * Update rules/linux/execution_c89_c99_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_c89_c99_binary.toml * Update rules/linux/execution_cpulimit_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_cpulimit_binary.toml * Update rules/linux/execution_expect_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_expect_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_expect_binary.toml * Update rules/linux/execution_find_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_find_binary.toml * Update rules/linux/execution_gcc_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_gcc_binary.toml * Update rules/linux/execution_mysql_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_mysql_binary.toml * Update rules/linux/execution_nice_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_nice_binary.toml * Update rules/linux/execution_ssh_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_ssh_binary.toml * Update execution_perl_tty_shell.toml * Update execution_python_tty_shell.toml * Update rules/linux/execution_apt_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_awk_binary_shell.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_c89_c99_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> * Update rules/linux/execution_expect_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_find_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_gcc_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_mysql_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_nice_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> * Update rules/linux/execution_ssh_binary.toml Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com> Co-authored-by: Justin Ibarra <brokensound77@users.noreply.github.com>
2022-03-29 09:16:21 -05:00
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+[metadata]
+creation_date = "2022/03/17"
+maturity = "production"
+updated_date = "2022/03/24"
+
+[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 = '''
+process where event.type == "start" and process.name in ("bash", "sh", "dash") and 
+  process.parent.name == "cpulimit" and process.parent.args == "-f" and 
+  process.parent.args in ("/bin/sh", "/bin/bash", "/bin/dash", "sh", "bash", "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/"
+