Ruben Groenewoud
91 lines
3.1 KiB
TOML
91 lines
3.1 KiB
TOML
[metadata]
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creation_date = "2025/04/29"
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integration = ["endpoint"]
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maturity = "production"
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updated_date = "2025/04/29"
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[rule]
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author = ["Elastic"]
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description = """
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This rule detects the modification and reading of kernel features through built-in commands. Attackers may collect
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information, disable or weaken Linux kernel protections. For example, an attacker may modify ASLR protection by
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disabling kernel.randomize_va_space, allow ptrace by setting kernel.yama.ptrace_scope to 0, or disable the
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NMI watchdog by setting kernel.nmi_watchdog to 0. These changes may be used to impair defenses and evade detection.
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"""
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from = "now-9m"
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index = [
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"logs-endpoint.events.process*",
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]
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language = "eql"
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license = "Elastic License v2"
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name = "Suspicious Kernel Feature Activity"
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risk_score = 21
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rule_id = "3aff6ab1-18bd-427e-9d4c-c5732110c261"
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severity = "low"
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tags = [
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"Domain: Endpoint",
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"OS: Linux",
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"Use Case: Threat Detection",
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"Tactic: Defense Evasion",
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"Tactic: Discovery",
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"Data Source: Elastic Defend",
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]
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timestamp_override = "event.ingested"
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type = "eql"
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query = '''
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process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
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process.command_line : (
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"*/etc/sysctl.conf*", "*/etc/sysctl.d/*", "*/proc/sys/kernel/nmi_watchdog*",
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"*/proc/sys/vm/nr_hugepages*", "*/proc/sys/kernel/yama/ptrace_scope*",
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"*/proc/sys/kernel/randomize_va_space*", "*/proc/sys/vm/drop_caches*",
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"*/proc/sys/kernel/sysrq*", "*grsecurity*", "*exec-shield*",
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"*kernel.randomize_va_space*", "*kernel.yama.ptrace_scope*",
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"*kernel.nmi_watchdog*", "*vm.nr_hugepages*", "*vm.drop_caches*",
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"*kernel.sysrq*"
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) and
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process.parent.executable != null and
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(
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(process.name == "tee" and process.args like "-*a*") or // also detects --append
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(process.name == "cat" and not process.parent.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish")) or
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(process.name == "grep" and process.args_count == 3 and not process.parent.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish")) or
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(process.name == "sysctl" and process.args like ("*-w*", "*--write*", "*=*")) or
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(process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish") and process.args == "-c" and process.args : "*echo *")
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)
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'''
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[[rule.threat]]
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framework = "MITRE ATT&CK"
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[rule.threat.tactic]
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name = "Defense Evasion"
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id = "TA0005"
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reference = "https://attack.mitre.org/tactics/TA0005/"
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[[rule.threat.technique]]
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name = "Impair Defenses"
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id = "T1562"
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reference = "https://attack.mitre.org/techniques/T1562/"
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[[rule.threat.technique.subtechnique]]
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name = "Indicator Blocking"
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id = "T1562.006"
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reference = "https://attack.mitre.org/techniques/T1562/006/"
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[[rule.threat.technique]]
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name = "Subvert Trust Controls"
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id = "T1553"
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reference = "https://attack.mitre.org/techniques/T1553/"
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[[rule.threat]]
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framework = "MITRE ATT&CK"
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[[rule.threat.technique]]
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id = "T1082"
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name = "System Information Discovery"
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reference = "https://attack.mitre.org/techniques/T1082/"
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[rule.threat.tactic]
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id = "TA0007"
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name = "Discovery"
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reference = "https://attack.mitre.org/tactics/TA0007/"
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