Imestartup
Table of Contents
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 our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1189 | Drive-by Compromise (Bundled Installers) | Initial Access | ATT&CK ↗ |
T1112 | Modify Registry (Altering browser configurations) | Defense Evasion | ATT&CK ↗ |
T1562.001 | Impair Defenses: Disable or Modify Tools (Abusing GPOs to lock settings) | Defense Evasion | ATT&CK ↗ |
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-RVM | Registry Value Modification Analysis | Detect | T1112 | Log Windows Event ID 4657 to monitor unauthorized modifications to system configuration and security settings. |
D3-RBI | Remote Browser Isolation | Isolate | T1189 | Execute untrusted web browsing sessions in disposable cloud containers to isolate drive-by exploits from local endpoints. |
D3-STA | Security Tool Anti-Tamper Enforcement | Harden | T1562.001 | Block unauthorized modification of antivirus registry flags and prevent stopping security agent services. |
Tiered Detection Rules (Cisco CAIRN Model)
Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_IMESTARTUP_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Imestartup"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "imestartup" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Imestartup (Advanced Threat) Execution & Triage
id: 1732377d-fdf5-56e0-9707-6c5e1eb5a429
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Imestartup malware family. Detects proxy execution, reflective DLL loading,
and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/imestartup
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1112
- attack.t1189
- attack.t1562_001
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \powershell.exe
- \cmd.exe
- \rundll32.exe
- \regsvr32.exe
CommandLine|contains:
- DownloadString
- IEX(
- '/s /n /u /i:'
- sc create
- start-process
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: highTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_IMESTARTUP_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Imestartup tradecraft"
tier = "T3 - Attribution Fingerprint"
confidence = "High (Confirmed Family Signature)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
// Core family identifier & heuristic payload signatures
$attrib_str = "imestartup" ascii wide nocase
$pe_magic = "MZ" ascii
$net_marker = "http" ascii nocase
condition:
uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}Containment & Response Steps
Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.
- Use the Windows Control Panel to uninstall the primary software bundle that delivered the hijacker.
- Critically, audit the Windows Registry (specifically the `Policies` hives) and delete any unauthorized Group Policies enforcing homepage or search settings.
- Deploy an enterprise adware removal tool to strip any remaining registry hooks and watchdog services.
- 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.
- Do not rely on simply changing the homepage in the browser settings GUI; the GPO will instantly override it on the next launch.
- 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)
- Search "imestartup" on Any.Run (Sandbox Sandbox)
- Search "imestartup" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Imestartup and what threat category does it belong to?
Imestartup is classified as a Advanced Threat. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Imestartup establish persistence and evade defensive controls?
Imestartup typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Imestartup compromise?
Security teams responding to Imestartup should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What lateral movement and credential access tactics does Imestartup leverage in enterprise intrusions?
Imestartup frequently utilizes privileged account harvesting techniques such as LSASS memory dumping, Kerberoasting, and token impersonation to escalate privileges. Once administrative credentials are acquired, it pivots across the victim network utilizing living-off-the-land binaries (LOLBins) such as WMI, PowerShell remoting, and PsExec, or abuses remote desktop protocols (RDP) to reach critical internal repositories and domain controllers.
How does Imestartup maintain covert communications and evade perimeter network monitoring?
Imestartup often relies on multi-stage command and control (C2) architectures utilizing encrypted protocols over standard web ports (HTTPS/443 or DNS tunneling) to blend in with legitimate enterprise network traffic. Many variants incorporate proxy networks, domain fronting, or cloud services (such as Microsoft Graph API, Google Drive, or Telegram) to masquerade C2 channels, bypassing traditional signature-based egress filtering.
How do I remove the Imestartup Advanced_Threat from Windows?
Manual removal of Imestartup is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Imestartup a virus or a Advanced_Threat?
Imestartup is classified as a Advanced_Threat. Unlike traditional viruses that infect files, modern malware like Imestartup typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Imestartup infection?
Symptoms of Imestartup can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Advanced_Threats
Want to prevent Imestartup and similar threats from compromising your organization? Read our comprehensive defensive guide: Think You've Been Hacked? What To Do First.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/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.