Imestartup

Overview

BrowserModifier:Win32/Imestartup is a persistent Potentially Unwanted Program (PUA) and browser hijacker specifically designed to forcefully alter a user's web browser settings. It locks the default homepage, new tab page, and search engine to a specific, monetized affiliate portal (often associated with aggressive Input Method Editors or Chinese freeware networks), making it extremely difficult for the user to revert the changes.

Understanding Imestartup Hijackers
To an end-user, an Imestartup infection is maddening. No matter how many times they manually change their homepage back to Google, it reverts to the unwanted portal upon the next reboot. For security analysts, this represents a sophisticated hijacking attempt. The software utilizes deep OS-level hooks, often abusing legitimate Windows features like Group Policy Objects (GPOs), to enforce its settings on the browser.

Execution and Hijacking Mechanics
Imestartup is typically distributed as a bundled payload alongside free software, particularly third-party language tools or media players (`T1189`). During installation, it actively searches the system for installed browsers (Chrome, Edge, Firefox). It doesn't just install an extension; it fundamentally alters the browser's core configuration files (like Chrome's `Preferences` JSON) (`T1112`). Crucially, to prevent the user from fixing it, Imestartup often establishes local Windows Group Policies (`T1562.001`) that 'manage' the browser, grey-out the homepage settings in the UI, and force the browser to always open the malicious URL.

Indicators of Compromise & Impact
The primary impact is a degraded user experience and the redirection of all search traffic through a monetized, potentially insecure affiliate network. Incident responders will observe users complaining about locked browser settings. EDR logs will flag the modification of browser preference files and, most importantly, the unauthorized creation of new registry keys under `HKLM\Software\Policies\Google\Chrome` (or similar browser policy paths).

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_IMESTARTUP {
    meta:
        description = "Detects Imestartup (advanced_threat)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "imestartup" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Imestartup Activity
id: 875948abbe6e231fc9806881e0c81a04
status: experimental
description: Detects generic indicators of the imestartup malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*imestartup*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Use the Windows Control Panel to uninstall the primary software bundle that delivered the hijacker.
2. Critically, audit the Windows Registry (specifically the `Policies` hives) and delete any unauthorized Group Policies enforcing homepage or search settings.
3. Deploy an enterprise adware removal tool to strip any remaining registry hooks and watchdog services.
4. Force a complete reset of all installed web browsers to factory defaults to clear the altered JSON preference files.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not rely on simply changing the homepage in the browser settings GUI; the GPO will instantly override it on the next launch.
2. Avoid ignoring the infection; forced search routing can expose users to secondary malvertising and phishing attacks.

References & External Analysis

• Search "imestartup" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: advanced_threat)

Explore other malware families in the same category:

• Carambisdu
• Drmsoft
• Autocleanpro
• Fontra
• Sillysharecopy

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/imestartup.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.