Windows Uncommon Remote Thread Creation In Browser Process

name: Windows Uncommon Remote Thread Creation In Browser Process
id: 634cce27-a3a6-4079-b0d6-3ced361a0aa9
version: 1
creation_date: '2026-06-29'
modification_date: '2026-06-29'
author: Teoderick Contreras, Nasreddine Bencherchali, Splunk
status: production
type: Anomaly
description: |-
    The following analytic identifies the creation of a remote thread by a process such as wermgr.exe or rundll32.exe into a browser process such as firefox.exe, chrome.exe, and others.
    These processes do not typically create remote threads, in browser processes.
    It leverages Sysmon EventID 8 to detect this behavior by monitoring SourceImage and TargetImage fields.
    This activity is significant because it is commonly associated with malware like Qakbot and IcedID, which injects malicious code into legitimate processes to steal information.
    If confirmed malicious, this activity could allow attackers to execute arbitrary code, escalate privileges, and exfiltrate sensitive data from the compromised host.
data_source:
    - Sysmon EventID 8
search: |-
    `sysmon`
    EventCode=8
    SourceImage IN (
        "*\\rundll32.exe",
        "*\\wermgr.exe"
    )
    TargetImage IN (
        "*\\Sputnik.exe",
        "*\\ChromePlus.exe",
        "*\\QIP Surf.exe",
        "*\\BlackHawk.exe",
        "*\\7Star.exe",
        "*\\Sleipnir5.exe",
        "*\\Citrio.exe",
        "*\\Chrome SxS.exe",
        "*\\Chrome.exe",
        "*\\Coowon.exe",
        "*\\CocCocBrowser.exe",
        "*\\Uran.exe",
        "*\\QQBrowser.exe",
        "*\\Orbitum.exe",
        "*\\Slimjet.exe",
        "*\\Iridium.exe",
        "*\\Vivaldi.exe",
        "*\\Chromium.exe",
        "*\\GhostBrowser.exe",
        "*\\CentBrowser.exe",
        "*\\Xvast.exe",
        "*\\Chedot.exe",
        "*\\SuperBird.exe",
        "*\\360Browser.exe",
        "*\\360Chrome.exe",
        "*\\dragon.exe",
        "*\\brave.exe",
        "*\\torch.exe",
        "*\\UCBrowser.exe",
        "*\\BliskBrowser.exe",
        "*\\Epic Privacy Browser.exe",
        "*\\nichrome.exe",
        "*\\AmigoBrowser.exe",
        "*\\KometaBrowser.exe",
        "*\\XpomBrowser.exe",
        "*\\msedge.exe",
        "*\\LiebaoBrowser.exe",
        "*\\AvastBrowser.exe",
        "*\\Kinza.exe",
        "*\\seamonkey.exe",
        "*\\icedragon.exe",
        "*\\cyberfox.exe",
        "*\\SlimBrowser.exe",
        "*\\palemoon.exe",
        "*\\opera.exe",
        "*\\yandex.exe",
        "*\\atom.exe",
        "*\\Chromodo.exe",
        "*\\360chrome.exe",
        "*\\360se.exe",
        "*\\Maxthon.exe",
        "*\\k-meleon.exe",
        "*\\SLBrowser.exe",
        "*\\Go!.exe",
        "*\\Secure Browser.exe",
        "*\\Elements Browser.exe",
        "*\\Mustang.exe",
        "*\\Suhba.exe",
        "*\\TorBro.exe",
        "*\\RockMelt.exe",
        "*\\Bromium.exe",
        "*\\Twinkstar.exe",
        "*\\iTop Private Browser.exe",
        "*\\CCleaner Browser.exe",
        "*\\AcWebBrowser.exe",
        "*\\CoolNovo.exe",
        "*\\spark.exe",
        "*\\iron.exe",
        "*\\Titan Browser.exe",
        "*\\AVG Browser.exe",
        "*\\UR Browser.exe",
        "*\\Flock.exe",
        "*\\CryptoTab Browser.exe",
        "*\\Sidekick.exe",
        "*\\SwingBrowser.exe",
        "*\\SalamWeb.exe",
        "*\\NetboxBrowser.exe",
        "*\\GarenaPlus.exe",
        "*\\InsomniacBrowser.exe",
        "*\\Viasat Browser.exe",
        "*\\whale.exe",
        "*\\falkon.exe",
        "*\\SogouExplorer.exe",
        "*\\firefox.exe",
        "*\\waterfox.exe",
        "*\\thunderbird.exe",
        "*\\basilisk.exe",
        "*\\BitTubeBrowser.exe"
    )
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
                  values(NewThreadId) as "NewThreadId"
                  values(StartAddress) as "StartAddress"
      by dest signature_id signature
         SourceProcessGuid SourceProcessId SourceImage
         TargetProcessGuid TargetProcessId TargetImage
         StartModule StartFunction vendor_product
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_uncommon_remote_thread_creation_in_browser_process_filter`
how_to_implement: |-
    To successfully implement this search, you need to be ingesting logs with the SourceImage, TargetImage, and EventCode executions from your endpoints related to create remote thread or injecting codes. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: No false positives have been identified at this time.
references:
    - https://news.sophos.com/en-us/2022/03/10/qakbot-decoded/
    - https://www.trellix.com/en-us/about/newsroom/stories/research/demystifying-qbot-malware.html
    - https://www.joesandbox.com/analysis/380662/0/html
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: The process [$SourceImage$] created a remote thread into the browser process [$TargetImage$] in host $dest$.
threat_objects:
    - field: SourceImage
      type: process_name
    - field: TargetImage
      type: process_name
analytic_story:
    - Qakbot
    - IcedID
    - Living Off The Land
asset_type: Endpoint
mitre_attack_id:
    - T1055.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test - Wermgr
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/qakbot/remote_thread/sysmon_wermgr_remote.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit
    - name: True Positive Test - Rundll32
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/icedid/inf_icedid/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit