Potential Masquerading as Browser Process

Status: production
Kind: building block (feeds higher-level correlation rules; not a standalone alert)
Severity: low
Time window: 9m
Author: Elastic
Source: github.com/elastic/detection-rules

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.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1554` Compromise Host Software Binary
Stealth	`T1036.001` Masquerading: Invalid Code Signature, `T1036.005` Masquerading: Match Legitimate Resource Name or Location

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation
Security-Auditing	Event ID 4688	A new process has been created.

Rule body elastic

[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/"

Stages and Predicates

Stage 1: `process`

process where host.os.type == "windows" and event.type == "start" and
  (
    (
      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
    (
      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
    (
      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
    (
      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
    (
      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
    (
      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
    (
      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
    (
      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
      )
    )
  )

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`event.type`	eq	`start` corpus 606 (elastic 606)
`process.hash.sha256`	ne	`ddc7a6c3a4b50d23daffe8e364c575fd7df9af9711b14d153b09553ddd3670a0`
`process.name`	wildcard	`BraveCrashHandler.exe` `BraveCrashHandler64.exe` `BraveUpdate.exe` `BraveUpdateComRegisterShell64.exe` `BraveUpdateOnDemand.exe` `BraveUpdateSetup.exe` `GoogleCrashHandler.exe` `GoogleCrashHandler64.exe` `GoogleUpdate.exe` `GoogleUpdateBroker.exe` `GoogleUpdateComRegisterShell64.exe` `GoogleUpdateOnDemand.exe` `GoogleUpdateSetup.exe` `Island.exe` `IslandCrashHandler.exe` `IslandCrashHandler64.exe` `IslandUpdate.exe` `IslandUpdateBroker.exe` `IslandUpdateComRegisterShell64.exe` `IslandUpdateOnDemand.exe` `IslandUpdateSetup.exe` `MicrosoftEdgeUpdate.exe` `MicrosoftEdgeUpdateBroker.exe` `MicrosoftEdgeUpdateComRegisterShell64.exe` `MicrosoftEdgeUpdateCore.exe` `MicrosoftEdgeUpdateSetup.exe` `MicrosoftEdgeUpdateSetup_X.exe` `MicrosoftEdgeWebview2Setup.exe` `MicrosoftEdge_X.exe` `brave.exe` corpus 3 (elastic 3) `brave_vpn_helper.exe` `browser_assistant.exe` `chrmstp.exe` `chrome.exe` corpus 7 (elastic 5, splunk 2) `chrome_proxy.exe` `default-browser-agent.exe` `elevation_service.exe` corpus 2 (elastic 2) `firefox.exe` corpus 2 (elastic 2) `identity_helper.exe` `maintenanceservice.exe` `maintenanceservice_installer.exe` `maintenanceservice_tmp.exe` `minidump-analyzer.exe` `msedge.exe` corpus 4 (elastic 4) `msedge_proxy.exe` `msedgerecovery.exe` `msedgewebview2.exe` `notification_helper.exe` `opera.exe` `opera_.exe` `pingsender.exe` `plugin-container.exe` `remote_assistance_host.exe` `remoting_native_messaging_host.exe` `whale.exe` corpus 2 (elastic 2) `whale_update.exe` `wusvc.exe`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Potential Masquerading as Browser Process

MITRE ATT&CK coverage

Event coverage

Rule body elastic

Stages and Predicates

Stage 1: `process`

Indicators

Keyboard shortcuts

Search operators

Potential Masquerading as Browser Process

MITRE ATT&CK coverage

Event coverage

Rule body elastic

Stages and Predicates

Stage 1: process

Indicators

Stage 1: `process`