Adrozek Browser Hijacker: Complete Analysis, Indicators Of Compromise (IOCs), MITRE ATT&CK

  Category:  BROWSER HIJACKER | 10th July 2026 | Author:  CSI'S TEAM

What Is Adrozek Browser Hijacker?

Adrozek Is A Sophisticated Browser-modifying Malware Family That Targets Multiple Web Browsers By Altering Browser Components, Changing Browser Settings, Injecting Malicious Code, And Redirecting Users To Attacker-controlled Advertisements And Search Results. Unlike Traditional Browser Hijackers That Simply Change A Homepage Or Search Engine, Adrozek Modifies Browser DLLs And Configuration Files To Inject Unauthorized Advertisements, Manipulate Affiliate Revenue, And Potentially Steal Browser Credentials.

First Publicly Documented In 2020 By Microsoft, Adrozek Was Distributed Through Drive-by Downloads And Malicious Websites Hosting Fake Software Installers. The Malware Affected Thousands Of Systems Globally By Silently Installing Itself And Modifying Chromium- And Mozilla-based Browsers.

Although Adrozek Primarily Focuses On Browser Manipulation And Ad Fraud, Its Persistence Mechanisms And Browser Modifications Make It A Significant Security Threat. It Can Also Disable Browser Security Features, Bypass Extension Verification, And Maintain Persistence Even After Browser Updates.

How Adrozek Works?

Once Executed, Adrozek Copies Itself Into A Randomly Named Folder Within The Program Files Or AppData Directories. It Establishes Persistence By Creating Registry Run Entries Or Scheduled Tasks.

After Installation, It Searches For Installed Browsers And Modifies Browser-specific Files Such As DLLs, Preferences, And Extension Configurations.

Its Primary Objectives Include:

• Injecting Advertisements Into Legitimate Websites

• Redirecting Search Results

• Modifying Browser Extensions

• Disabling Browser Security Protections

• Replacing Legitimate Browser DLL Files

• Collecting Browser Credentials

• Generating Affiliate Advertising Revenue

The Malware Continues Operating In The Background While Intercepting Browsing Activity.

Technical Characteristics

Infection Chain

1. User Downloads Fake Software.

2. Installer Executes Malicious Payload.

3. Malware Copies Itself Into Hidden Directory.

4. Registry Persistence Is Established.

5. Installed Browsers Are Detected.

6. Browser DLL Files Are Modified.

7. Browser Settings Are Altered.

8. Security Features Are Disabled.

9. Malicious Advertisements Begin Appearing.

10. Search Traffic Is Redirected.

Infected Operating Systems

Adrozek Primarily Targets Microsoft Windows Systems.

Supported Targets Include:

• Windows 7

• Windows 8

• Windows 8.1

• Windows 10

• Windows 11 (variants May Still Function)

• Windows Server Editions (limited Observations)

The Malware Does Not Target:

• Linux

• macOS

• Android

• iOS

Targeted Browsers

Adrozek Was Designed To Compromise Several Popular Browsers.

These Include:

• Google Chrome

• Microsoft Edge (Chromium)

• Mozilla Firefox

• Yandex Browser

The Malware Modifies Browser Files Differently Depending On The Browser Architecture.

Browser Files Modified

Common Browser Components Modified Include:

Google Chrome

• chrome.dll

• Preferences

• Secure Preferences

• Local State

• Extension Configuration Files

Microsoft Edge

• msedge.dll

• Preferences

• Secure Preferences

• Browser Policies

Mozilla Firefox

• xul.dll

• omni.ja

• prefs.js

• extensions.json

Yandex Browser

• browser.dll

• Preferences

• Extension Settings

Files Dropped By Adrozek

Common Dropped Files Include:

[random].exe

[random].dll

[random].dat

[random].tmp

Installation Directories:

C:\Program Files\[Random Folder]\

C:\Users\<User>\AppData\Local\[Random Folder]\

C:\Users\<User>\AppData\Roaming\[Random Folder]\

Configuration Files:

config.dat

Settings.dat

Version.dat

Install.log

Browser Extensions Modified

Rather Than Installing Traditional Malicious Extensions, Adrozek Often Modifies Existing Extension Configurations Or Bypasses Extension Verification.

Affected Components Include:

• Chrome Extension Preferences

• Firefox Extension Registry

• Edge Extension Configuration

• Browser Policies

• Secure Preferences

• Local State

It May Also Enable Unauthorized Advertising Extensions Or Inject JavaScript Into Existing Browser Processes.

Registry Changes

Common Registry Locations:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

HKCU\Software\Policies\Google\Chrome

HKLM\Software\Policies\Microsoft\Edge

Persistence Mechanisms

Adrozek Maintains Persistence Through:

• Registry Run Keys

• Startup Folders

• Scheduled Tasks

• Browser Startup Configuration

• Browser DLL Replacement

• Browser Preference Modification

Countries Affected By Adrozek

Microsoft Reported Widespread Adrozek Activity Across Multiple Regions.

Frequently Affected Countries Included:

• India

• United States

• United Kingdom

• Germany

• France

• Italy

• Spain

• Canada

• Brazil

• Australia

• Russia

• Turkey

• Poland

• Mexico

• South Korea

• Indonesia

Campaigns Were Observed Globally Due To Malicious Download Sites And Fake Software Installers.

Estimated Impact

During Its Major Campaign:

• Hundreds Of Thousands Of Malicious URLs Were Active.

• Thousands Of Malware Samples Were Distributed.

• Tens Of Thousands Of Computers Were Infected Worldwide.

• Multiple Browser Families Were Successfully Compromised.

Symptoms Of Infection

Users May Notice:

• Browser Homepage Changes

• Unknown Advertisements

• Pop-up Ads

• Redirected Searches

• Slow Browser Performance

• Disabled Browser Security

• Unauthorized Browser Extensions

• High CPU Usage

• Increased Memory Consumption

• Unexpected Affiliate Websites

Indicators Of Compromise (IOCs)

File Names

[random].exe

[random].dll

Config.dat

Settings.dat

Install.log

Version.dat

Registry Keys

HKCU\Software\Microsoft\Windows\CurrentVersion\Run

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

HKCU\Software\Policies\Google\Chrome

HKLM\Software\Policies\Microsoft\Edge

Suspicious Directories

C:\Program Files\[Random Folder]\

C:\Users\<User>\AppData\Local\[Random Folder]\

C:\Users\<User>\AppData\Roaming\[Random Folder]\

Behavioral Indicators

• Modified Browser DLLs

• Browser Preference Tampering

• Unauthorized Advertisements

• Search Engine Redirection

• Browser Update Interference

• Extension Verification Bypass

• Unexpected Browser Policies

MITRE ATT&CK Techniques

YARA Detection Rule

rule Adrozek_Browser_Hijacker
{
    Meta:
        Description = "Detects Adrozek Browser Hijacker"

    Strings:
        $a = "Secure Preferences"
        $b = "Local State"
        $c = "chrome.dll"
        $d = "msedge.dll"
        $e = "prefs.js"

    Condition:
        2 Of ($a,$b,$c,$d,$e)
}

Sigma Detection Rule

title: Adrozek Browser Modification

Id: 2d54a1b5-7d3e-4d8c-a1f7-acde48001122

Status: Experimental

Logsource:
  Category: File_event
  Product: Windows

Detection:
  Selection:
    TargetFilename|contains:
      - "chrome.dll"
      - "msedge.dll"
      - "prefs.js"
      - "Secure Preferences"

  Condition: Selection

Level: High

Windows Defender Detection

Possible Detections Include:

• BrowserModifier

• Trojan:Win32/Adrozek

• TrojanDownloader

• BrowserHijacker

• PUA:Win32

How To Remove Adrozek?

Recommended Removal Steps:

1. Disconnect The Computer From The Internet.

2. Boot Windows Into Safe Mode.

3. Run A Full Antivirus Scan Using An Up-to-date Security Solution.

4. Remove Malicious Files And Registry Entries.

5. Reinstall Affected Browsers To Restore Modified DLLs And Configuration Files.

6. Reset Browser Settings And Search Providers.

7. Remove Unknown Browser Extensions.

8. Change Saved Passwords After Cleanup, As Browser Credentials May Have Been Exposed.

9. Update Windows And Browsers To The Latest Versions.

Prevention Best Practices

To Reduce The Risk Of Adrozek Infection:

• Download Software Only From Trusted Vendors.

• Keep Browsers And Windows Updated.

• Use Reputable Endpoint Protection.

• Avoid Cracked Software And Unofficial Installers.

• Enable Browser Security Features.

• Regularly Review Installed Extensions.

• Monitor Browser Policy Changes.

• Restrict Administrative Privileges Where Possible.

• Educate Users About Phishing And Fake Download Sites.

Frequently Asked Questions (FAQ)

Is Adrozek A Virus?

Adrozek Is Generally Classified As Browser-modifying Malware Or A Browser Hijacker. It Also Exhibits Trojan-like Behavior Because It Alters Browser Components Without User Consent.

Which Browsers Does Adrozek Target?

It Primarily Targets Google Chrome, Microsoft Edge (Chromium), Mozilla Firefox, And Yandex Browser.

Can Adrozek Steal Passwords?

Yes. Some Variants Have Been Observed Extracting Credentials Stored In Browsers By Interfering With Browser Security Mechanisms.

How Does Adrozek Spread?

The Malware Has Primarily Been Distributed Through Fake Software Installers, Malicious Websites, And Drive-by Download Campaigns.

Does Reinstalling The Browser Remove Adrozek?

Reinstalling The Browser Can Restore Modified Browser Files, But The Underlying Malware And Persistence Mechanisms Must Be Removed First To Prevent Reinfection.

What Operating Systems Are Affected?

Adrozek Mainly Targets Windows Systems, Including Windows 7, Windows 8/8.1, Windows 10, Windows 11, And Some Windows Server Editions.

Is Adrozek Ransomware?

No. Adrozek Does Not Encrypt Files Or Demand Payment. Its Primary Purpose Is Browser Manipulation, Ad Fraud, And, In Some Cases, Credential Theft.

Can Antivirus Software Detect Adrozek?

Yes. Modern Antivirus And Endpoint Detection Solutions Can Identify Known Adrozek Variants Through Signatures, Behavioral Analysis, And Heuristic Detection.

What Are The Main Indicators Of Compromise?

Common Indicators Include Modified Browser DLLs, Altered Browser Preferences, Suspicious Files In AppData Or Program Files, Registry Run Entries, Unexpected Advertisements, And Search Engine Redirections.

Why Is Adrozek Considered Dangerous?

Because It Modifies Trusted Browser Components, Can Disable Browser Protections, Inject Unauthorized Advertisements, Redirect Web Traffic, And Potentially Compromise Stored Credentials, Making It More Advanced Than Typical Browser Hijackers.

Conclusion

Adrozek Represents A More Advanced Class Of Browser Hijacker That Goes Beyond Changing Browser Settings. By Modifying Browser Binaries, Manipulating Extension Configurations, Disabling Security Mechanisms, And Redirecting User Traffic, It Enables Persistent Advertising Fraud And May Expose Sensitive Information Such As Stored Credentials. Organizations And Individuals Can Reduce Their Exposure By Maintaining Updated Systems, Limiting Software Installation To Trusted Sources, Monitoring Browser Integrity, And Deploying Layered Endpoint Security With Behavioral Detection Capabilities.

Malware Removal Guide For PC

Malware Removal Guide For Web Browsers

Prevent Future Malware

Summary - Malware Removal Guide

Guide For VPN Uses

Malware Removal Guide – PC And Web Browser

PART 1: Remove Malware From Your PC (Windows)

Step 1: Boot Into Safe Mode

• Restart Your PC And Press F8 (or Shift + F8 For Some Systems) Before Windows Loads.

• Choose Safe Mode With Networking.

Safe Mode Prevents Most Malware From Loading.

Step 2: Uninstall Suspicious Programs

1. Press Win + R, Type appwiz.cpl, And Press Enter.

2. Sort By Install Date And Uninstall Unknown Or Recently Added Programs.

Step 3: Run A Malware Scan

Use A Trusted Anti-malware Tool:

Malwarebytes – https://www.malwarebytes.com

Screenshot Of Malwarebytes - Visit Links

Microsoft Defender – Built Into Windows 10/11

HitmanPro, ESET Online Scanner, Or Kaspersky Virus Removal Tool

ZoneAlarm Pro Antivirus + Firewall NextGen

VIPRE Antivirus - US And Others Countries, | India

VIPRE Antivirus - Mac

F-Secure Total - Global

Run A Full Scan And Delete/quarantine Detected Threats.

Step 4: Delete Temporary Files

1. Press Win + R, Type temp → Delete All Files.

2. Press Win + R, Type %temp% → Delete All Files.

3. Use Disk Cleanup: cleanmgr In The Run Dialog.

Step 5: Reset Hosts File

1. Go To: C:\Windows\System32\drivers\etc

2. Open hosts File With Notepad.

3. Replace With Default Content:

Step 6: Check Startup Programs

1. Press Ctrl + Shift + Esc → Open Task Manager

2. Go To Startup Tab

3. Disable Any Suspicious Entries.

Step 7: Reset Network Settings

1. Open Command Prompt As Administrator.

2. Run These Commands:

netsh Winsock Reset

netsh Int Ip Reset

ipconfig /flushdns

PART 2: Remove Malware From Web Browsers

? Common Signs Of Malware In Browser:

• Unwanted Homepage Or Search Engine

• Pop-ups Or Redirects

• Unknown Extensions Installed

Step 1: Remove Suspicious Extensions

For Chrome:

• Go To: chrome://extensions/

• Remove Anything Unfamiliar

For Firefox:

• Go To: about:addons → Extensions

• Remove Suspicious Add-ons

For Edge:

• Go To: edge://extensions/

• Uninstall Unknown Add-ons

Step 2: Reset Browser Settings

Chrome:

• Go To chrome://settings/reset → "Restore Settings To Their Original Defaults"

Firefox:

• Go To about:support → "Refresh Firefox"

Edge:

• Go To edge://settings/resetProfileSettings → "Reset Settings"

Step 3: Clear Cache And Cookies

All Browsers:

• Use Ctrl + Shift + Del → Select All Time

• Clear Cookies, Cached Files, And Site Data

Step 4: Check Search Engine & Homepage Settings

Make Sure They Are Not Hijacked.

• Chrome: chrome://settings/search

• Firefox: about:preferences#search

• Edge: edge://settings/search

Step 5: Use Browser Cleanup Tools (Optional)

• Chrome: chrome://settings/cleanup

• Use Malwarebytes Browser Guard For Real-time Browser Protection.

FINAL TIPS: Prevent Future Malware

• Always Download Software From Trusted Sources.

• Keep Windows, Browsers, And Antivirus Updated.

• Avoid Clicking Suspicious Links Or Ads.

• Use ad Blockers And reputable Antivirus Software.

• Backup Your Files Regularly.

Short Summary: Malware Removal Guide (PC & Web Browser)

To Remove Malware From Your Windows PC, Start By Booting Into Safe Mode, Uninstalling Suspicious Programs, And Scanning With Trusted Anti-malware Tools Like Malwarebytes. Clear Temporary Files, Reset Your Network Settings, And Check Startup Apps For Anything Unusual.

For web Browsers, Remove Unwanted Extensions, Reset Browser Settings, Clear Cache And Cookies, And Ensure Your Homepage And Search Engine Haven’t Been Hijacked. Use Cleanup Tools Like Chrome Cleanup Or Browser Guard For Added Protection.

?? Prevention Tips: Keep Software Updated, Avoid Suspicious Downloads, And Use Antivirus Protection Plus Browser Ad Blockers. Regular Backups Are Essential.

VPN - How To Use IT

1. Choose A Trusted VPN Provider

• Why It Matters: Not All VPNs Offer Malware Protection.

• What To Look For: Providers With built-in Malware/ad/tracker Blockers (e.g., NordVPN’s Threat Protection, ProtonVPN’s NetShield).

• Nord VPN
• Hide.me VPN

2. Enable Kill Switch

• Purpose: Prevents Data Leaks If Your VPN Connection Drops.

• Benefit: Ensures Your Real IP And Browsing Activity Aren’t Exposed To Malware-distributing Websites.

3. Use VPN With DNS Leak Protection

• Why It Matters: DNS Leaks Can Expose Your Online Activity To Attackers.

• Solution: Enable DNS Leak Protection In Your VPN Settings Or Use A Secure DNS Like Cloudflare (1.1.1.1).

4. Avoid Free VPNs

• Risk: Free VPNs Often Contain Malware, Sell User Data, Or Lack Security Features.

• Better Option: Use Reputable Paid VPNs That Offer security Audits And Transparent Privacy Policies.

5. Use VPN With Anti-Phishing Tools

• Some VPNs Block Known Phishing And Malicious Sites.

• Example: Surfshark’s CleanWeb, CyberGhost’s Content Blocker.

6. Keep Your VPN App Updated

• Reason: Security Patches Fix Known Vulnerabilities.

• Tip: Enable Auto-updates Or Check For Updates Weekly.

. Use VPN On All Devices

• Scope: Malware Can Enter Through Phones, Tablets, Or IoT Devices.

• Solution: Install VPN Apps On Every Internet-connected Device.

8. Don’t Rely On VPN Alone

• Fact: VPNs Do Not Remove Or Detect Malware On Your System.

• Complement It With:

  • Antivirus Software

  • Firewall

  • Browser Extensions For Script Blocking

9. Avoid Clicking Unknown Links While VPN Is On

• VPN Encrypts Traffic But Can’t Stop Malware From Executing If You Download Infected Files.

10. Use VPN With Split Tunneling Cautiously

• Split Tunneling Allows Certain Apps/sites To Bypass VPN.

• Tip: Never Exclude Browsers, Email Clients, Or Download Managers From VPN Tunneling.

Short Note - VPN Uses

A VPN (Virtual Private Network) Enhances Your Online Privacy By Encrypting Your Internet Traffic And Masking Your IP Address. It Protects Your Data On Public Wi-Fi, Hides Browsing Activity From Hackers And ISPs, And Helps Bypass Geo-restrictions. VPNs Also Add A Layer Of Defense Against Malware By Blocking Malicious Websites And Trackers When Using Advanced Features. However, A VPN Does Not Remove Existing Malware Or Act As Antivirus Software. For Full Protection, Combine VPN Use With Antivirus Tools, Regular Software Updates, And Cautious Browsing Habits. Always Choose A Reputable VPN Provider With Strong Security And Privacy Policies.