sigma-rules/rules_building_block/defense_evasion_masquerading_browsers.toml

[metadata]
creation_date = "2023/08/02"
integration = ["endpoint"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/10/13"
bypass_bbr_timing = true

[rule]
author = ["Elastic"]
description = """
Identifies suspicious instances of browser processes, such as unsigned or signed with unusual certificates, that can
indicate an attempt to conceal malicious activity, bypass security features such as allowlists, or trick users into
executing malware.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Potential Masquerading as Browser Process"
risk_score = 21
rule_id = "5b9eb30f-87d6-45f4-9289-2bf2024f0376"
severity = "low"
tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Defense Evasion", "Tactic: Persistence", "Rule Type: BBR", "Data Source: Elastic Defend"]
timestamp_override = "event.ingested"
building_block_type = "default"
type = "eql"

query = '''
process where host.os.type == "windows" and event.type == "start" and
  (
    /* Chrome Related Processes */
    (process.name : (
      "chrome.exe", "GoogleUpdate.exe", "GoogleCrashHandler64.exe", "GoogleCrashHandler.exe",
      "GoogleUpdateComRegisterShell64.exe", "GoogleUpdateSetup.exe", "GoogleUpdateOnDemand.exe",
      "chrome_proxy.exe", "remote_assistance_host.exe", "remoting_native_messaging_host.exe",
      "GoogleUpdateBroker.exe"
     ) and not
      (process.code_signature.subject_name : ("Google LLC", "Google Inc") and process.code_signature.trusted == true)
     and not
      (
        process.executable : (
          "?:\\Program Files\\HP\\Sure Click\\servers\\chrome.exe",
          "?:\\Program Files\\HP\\Sure Click\\*\\servers\\chrome.exe"
        ) and
        process.code_signature.subject_name : ("Bromium, Inc.") and process.code_signature.trusted == true
      ) and
     not (
       process.executable : (
         "?:\\Users\\*\\AppData\\Local\\ms-playwright\\chromium-*\\chrome-win\\chrome.exe",
         "?:\\Users\\*\\AppData\\Local\\Programs\\synthetics-recorder\\resources\\local-browsers\\chromium-*\\chrome-win\\chrome.exe",
         "*\\node_modules\\puppeteer\\.local-chromium\\win64-*\\chrome-win\\chrome.exe",
         "?:\\Program Files (x86)\\Invicti Professional Edition\\chromium\\chrome.exe",
         "?:\\Program Files\\End2End, Inc\\ARMS Html Engine\\chrome.exe",
         "?:\\Users\\*\\AppData\\Local\\*BurpSuitePro\\burpbrowser\\*\\chrome.exe",
         "?:\\Users\\*\\AppData\\Roaming\\*BurpSuite\\burpbrowser\\*\\chrome.exe"
       ) and process.args: (
               "--enable-features=NetworkService,NetworkServiceInProcess",
               "--type=crashpad-handler", "--enable-automation", "--disable-xss-auditor"
             )
     )
    ) or

    /* MS Edge Related Processes */
    (process.name : (
      "msedge.exe", "MicrosoftEdgeUpdate.exe", "identity_helper.exe", "msedgewebview2.exe",
      "MicrosoftEdgeWebview2Setup.exe", "MicrosoftEdge_X*.exe", "msedge_proxy.exe",
      "MicrosoftEdgeUpdateCore.exe", "MicrosoftEdgeUpdateBroker.exe", "MicrosoftEdgeUpdateSetup_X*.exe",
      "MicrosoftEdgeUpdateComRegisterShell64.exe", "msedgerecovery.exe", "MicrosoftEdgeUpdateSetup.exe"
     ) and not
      (process.code_signature.subject_name : "Microsoft Corporation" and process.code_signature.trusted == true)
     and not
      (
        process.name : "msedgewebview2.exe" and
        process.code_signature.subject_name : ("Bromium, Inc.") and process.code_signature.trusted == true
      )
    ) or

    /* Brave Related Processes */
    (process.name : (
      "brave.exe", "BraveUpdate.exe", "BraveCrashHandler64.exe", "BraveCrashHandler.exe",
      "BraveUpdateOnDemand.exe", "brave_vpn_helper.exe", "BraveUpdateSetup*.exe",
      "BraveUpdateComRegisterShell64.exe"
     ) and not
      (process.code_signature.subject_name : "Brave Software, Inc." and process.code_signature.trusted == true)
    ) or

    /* Firefox Related Processes */
    (process.name : (
      "firefox.exe", "pingsender.exe", "default-browser-agent.exe", "maintenanceservice.exe",
      "plugin-container.exe", "maintenanceservice_tmp.exe", "maintenanceservice_installer.exe",
      "minidump-analyzer.exe"
     ) and not
      (process.code_signature.subject_name : "Mozilla Corporation" and process.code_signature.trusted == true)
     and not
      (
        process.name : "default-browser-agent.exe" and
        process.code_signature.subject_name : ("WATERFOX LIMITED") and process.code_signature.trusted == true
      )
    ) or

    /* Island Related Processes */
    (process.name : (
      "Island.exe", "IslandUpdate.exe", "IslandCrashHandler.exe", "IslandCrashHandler64.exe",
      "IslandUpdateBroker.exe", "IslandUpdateOnDemand.exe", "IslandUpdateComRegisterShell64.exe",
      "IslandUpdateSetup.exe"
     ) and not
      (process.code_signature.subject_name : "Island Technology Inc." and process.code_signature.trusted == true)
    ) or

    /* Opera Related Processes */
    (process.name : (
      "opera.exe", "opera_*.exe", "browser_assistant.exe"
     ) and not
      (process.code_signature.subject_name : "Opera Norway AS" and process.code_signature.trusted == true)
    ) or

    /* Whale Related Processes */
    (process.name : (
      "whale.exe", "whale_update.exe", "wusvc.exe"
     ) and not
      (process.code_signature.subject_name : "NAVER Corp." and process.code_signature.trusted == true)
    ) or

    /* Chromium-based Browsers processes */
    (process.name : (
      "chrmstp.exe", "notification_helper.exe", "elevation_service.exe"
     ) and not
      (process.code_signature.subject_name : (
        "Island Technology Inc.",
        "Citrix Systems, Inc.",
        "Brave Software, Inc.",
        "Google LLC",
        "Google Inc",
        "Microsoft Corporation",
        "NAVER Corp.",
        "AVG Technologies USA, LLC",
        "Avast Software s.r.o."
       ) and process.code_signature.trusted == true
      )
    )
  )
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1036"
name = "Masquerading"
reference = "https://attack.mitre.org/techniques/T1036/"

[[rule.threat.technique.subtechnique]]
id = "T1036.001"
name = "Invalid Code Signature"
reference = "https://attack.mitre.org/techniques/T1036/001/"

[[rule.threat.technique.subtechnique]]
id = "T1036.005"
name = "Match Legitimate Name or Location"
reference = "https://attack.mitre.org/techniques/T1036/005/"


[rule.threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"

[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1554"
name = "Compromise Client Software Binary"
reference = "https://attack.mitre.org/techniques/T1554/"

[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"