Detect browser session hijacking via privilege, handle access, and remote thread into browsers

ID: DET0507
Domains: Enterprise
Analytics: AN1398
Version: 1.0
Created: 21 October 2025
Last Modified: 21 October 2025

Analytics

AN1398

Adversary gains high integrity or special privileges (e.g., SeDebugPrivilege), locates a running browser process, opens it with write/inject rights, and modifies it (e.g., CreateRemoteThread / DLL load) to inherit cookies/tokens or establish a browser pivot. Optional step: create a new logon session or use explicit credentials, then drive the victim browser to intranet resources.

Log Sources
Data Component Name Channel
Logon Session Metadata (DC0088) WinEventLog:Security EventCode=4672
User Account Metadata (DC0013) WinEventLog:Security EventCode=4673
Logon Session Creation (DC0067) WinEventLog:Security EventCode=4624
Process Access (DC0035) WinEventLog:Sysmon EventCode=10
Process Modification (DC0020) WinEventLog:Sysmon EventCode=8
Module Load (DC0016) WinEventLog:Sysmon EventCode=7
Network Connection Creation (DC0082) WinEventLog:Sysmon EventCode=3
Mutable Elements
Field Description
BrowserList Set of monitored browsers (chrome.exe, msedge.exe, firefox.exe, iexplore.exe). Adjust per fleet.
AccessMaskSet Access rights implying injection (e.g., 0x1FFFFF, 0x1F3FF, VM_WRITE, VM_OPERATION, CREATE_THREAD). Tune by EDR mapping.
SignerAllowList Allowed module signers within browser processes (e.g., Microsoft, Google). Helps flag unsigned/unknown ImageLoad into browsers.
InternalCIDR Enterprise internal ranges or DNS suffixes to identify intranet pivoting via the browser.
TimeWindow Correlation interval (e.g., 10–20 minutes) linking privilege gain → access → modification → network usage.
ParentAllowList Legitimate tools that may automate browsers (e.g., Selenium drivers). Reduce FPs by allowlisting.
UserContext Scope analytics to high-value users, admin workstations, or servers where browsers shouldn’t be automated.