sigma-rules/rules_building_block/defense_evasion_masquerading_browsers.toml

[metadata]
bypass_bbr_timing = true
creation_date = "2023/08/02"
integration = ["endpoint"]
maturity = "production"
updated_date = "2025/05/05"

[rule]
author = ["Elastic"]
building_block_type = "default"
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.process-*"]
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"
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 in ("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 : "?:\\Program Files\\dynatrace\\synthetic\\Chrome-bin\\chrome.exe" and
        process.code_signature.subject_name == "Dynatrace LLC" and process.code_signature.trusted == true
      ) and
      not (
        process.executable : "?:\\Users\\*\\Desktop\\CentBrowser\\chrome.exe" and
        process.code_signature.subject_name == "MV INFORMATICA NORDESTE LTDA" 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\\*\\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",
          "?:\\Gradient\\Connector.Service\\runtimes\\win-x64\\native\\chrome.exe",
          "?:\\Program Files (x86)\\Netsparker Enterprise Agent-?\\chromium\\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 in ("Bromium, Inc.", "Amazon.com Services LLC", "Code Systems Corporation") and
        process.code_signature.trusted == true
      ) and
      not process.executable : "?:\\Program Files (x86)\\Microsoft\\EdgeUpdate\\MicrosoftEdgeUpdate.exe"
    ) 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 in ("Brave Software, Inc.", "Google 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 in ("WATERFOX LIMITED") and process.code_signature.trusted == true
      ) and
      not process.hash.sha256 == "ddc7a6c3a4b50d23daffe8e364c575fd7df9af9711b14d153b09553ddd3670a0" and
      not process.executable : "?:\\Users\\*\\AppData\\Local\\ms-playwright\\firefox-*\\firefox\\firefox.exe"
    ) 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 in ("Opera Norway AS", "Opera Software 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 in (
          "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.",
          "PIRIFORM SOFTWARE LIMITED",
          "NortonLifeLock Inc.",
          "Opera Norway AS"
        ) 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 Resource 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 Host Software Binary"
reference = "https://attack.mitre.org/techniques/T1554/"


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