Hilton
ccfc931fbd
* Tunes Unusual Parent Process for cmd.exe rule to exclude oobe activity
When dllhost.exe is called with the "/Processid:{CA8C87C1-929D-45BA-94DB-EF8E6CB346AD}" argument it is creating an "OOBE Elevated Object Server" as per https://strontic.github.io/xcyclopedia/library/clsid_ca8c87c1-929d-45ba-94db-ef8e6cb346ad.html
Out of the box experience is part of the Windows autopilot and therefore should be legitimate behaviour.
* simplified detection logic by utilising process.parent.args
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Co-authored-by: Justin Ibarra <16747370+brokensound77@users.noreply.github.com>
72 lines
2.7 KiB
TOML
72 lines
2.7 KiB
TOML
[metadata]
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creation_date = "2020/08/21"
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integration = ["endpoint", "windows"]
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maturity = "production"
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min_stack_comments = "New fields added: required_fields, related_integrations, setup"
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min_stack_version = "8.3.0"
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updated_date = "2023/06/22"
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[rule]
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author = ["Elastic"]
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description = "Identifies a suspicious parent child process relationship with cmd.exe descending from an unusual process."
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from = "now-9m"
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index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*", "endgame-*"]
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language = "eql"
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license = "Elastic License v2"
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name = "Unusual Parent Process for cmd.exe"
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note = """## Setup
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If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
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"""
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risk_score = 47
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rule_id = "3b47900d-e793-49e8-968f-c90dc3526aa1"
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severity = "medium"
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tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Execution", "Data Source: Elastic Endgame", "Data Source: Elastic Defend"]
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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 == "windows" and event.type == "start" and
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process.name : "cmd.exe" and
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process.parent.name : ("lsass.exe",
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"csrss.exe",
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"epad.exe",
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"regsvr32.exe",
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"dllhost.exe",
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"LogonUI.exe",
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"wermgr.exe",
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"spoolsv.exe",
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"jucheck.exe",
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"jusched.exe",
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"ctfmon.exe",
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"taskhostw.exe",
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"GoogleUpdate.exe",
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"sppsvc.exe",
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"sihost.exe",
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"slui.exe",
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"SIHClient.exe",
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"SearchIndexer.exe",
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"SearchProtocolHost.exe",
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"FlashPlayerUpdateService.exe",
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"WerFault.exe",
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"WUDFHost.exe",
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"unsecapp.exe",
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"wlanext.exe" ) and
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not (process.parent.name : "dllhost.exe" and process.parent.args : "/Processid:{CA8C87C1-929D-45BA-94DB-EF8E6CB346AD}")
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'''
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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 = "T1059"
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name = "Command and Scripting Interpreter"
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reference = "https://attack.mitre.org/techniques/T1059/"
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[rule.threat.tactic]
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id = "TA0002"
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name = "Execution"
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reference = "https://attack.mitre.org/tactics/TA0002/"
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