Justin Ibarra
46d5e37b76
* min_stack all rules to 8.3 * bump date Co-authored-by: Mika Ayenson <mika.ayenson@elastic.co>
94 lines
3.3 KiB
TOML
94 lines
3.3 KiB
TOML
[metadata]
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creation_date = "2022/07/03"
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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 = "2022/08/24"
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[rule]
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author = ["Elastic"]
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description = """
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Identifies the execution of a browser process to open an HTML file with high entropy and size. Adversaries may smuggle
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data and files past content filters by hiding malicious payloads inside of seemingly benign HTML files.
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"""
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from = "now-9m"
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index = ["logs-endpoint.events.*"]
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language = "eql"
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license = "Elastic License v2"
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name = "Suspicious HTML File Creation"
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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 = "f0493cb4-9b15-43a9-9359-68c23a7f2cf3"
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severity = "medium"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Initial Access"]
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type = "eql"
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query = '''
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sequence by user.id with maxspan=5m
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[file where event.action in ("creation", "rename") and
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file.extension : ("htm", "html") and
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file.path : ("?:\\Users\\*\\Downloads\\*",
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"?:\\Users\\*\\Content.Outlook\\*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\Temp?_*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\7z*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\Rar$*") and
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((file.Ext.entropy >= 5 and file.size >= 150000) or file.size >= 1000000)]
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[process where event.action == "start" and
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(
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(process.name in ("chrome.exe", "msedge.exe", "brave.exe", "whale.exe", "browser.exe", "dragon.exe", "vivaldi.exe", "opera.exe")
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and process.args == "--single-argument") or
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(process.name == "iexplore.exe" and process.args_count == 2) or
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(process.name in ("firefox.exe", "waterfox.exe") and process.args == "-url")
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)
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and process.args : ("?:\\Users\\*\\Downloads\\*.htm*",
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"?:\\Users\\*\\Content.Outlook\\*.htm*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\Temp?_*.htm*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\7z*.htm*",
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"?:\\Users\\*\\AppData\\Local\\Temp\\Rar$*.htm*")]
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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 = "T1566"
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name = "Phishing"
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reference = "https://attack.mitre.org/techniques/T1566/"
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[[rule.threat.technique.subtechnique]]
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id = "T1566.001"
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name = "Spearphishing Attachment"
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reference = "https://attack.mitre.org/techniques/T1566/001/"
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[[rule.threat.technique.subtechnique]]
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id = "T1566.002"
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name = "Spearphishing Link"
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reference = "https://attack.mitre.org/techniques/T1566/002/"
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[rule.threat.tactic]
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id = "TA0001"
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name = "Initial Access"
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reference = "https://attack.mitre.org/tactics/TA0001/"
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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 = "T1027"
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name = "Obfuscated Files or Information"
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reference = "https://attack.mitre.org/techniques/T1027/"
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[[rule.threat.technique.subtechnique]]
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id = "T1027.006"
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name = "HTML Smuggling"
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reference = "https://attack.mitre.org/techniques/T1027/006/"
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[rule.threat.tactic]
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id = "TA0005"
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name = "Defense Evasion"
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reference = "https://attack.mitre.org/tactics/TA0005/"
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