Adware:Win32/Montiera.B is a persistent advertising program that infiltrates Windows systems to inject unwanted advertisements into web browsers and hijack search results. First documented in the mid-2010s, this adware variant belongs to the Montiera family of potentially unwanted programs (PUPs) that prioritize revenue generation through forced ad displays over user experience. While not as destructive as ransomware or data-stealing trojans, Montiera.B degrades system performance, tracks browsing activity, and exposes users to potentially malicious websites through aggressive redirect chains.
The adware typically arrives bundled with free software downloads or through deceptive "update required" prompts on sketchy websites. Once installed, it establishes multiple persistence mechanisms that make removal challenging for average users. Beyond the annoyance factor, Montiera.B represents a genuine privacy concern—it monitors your browsing habits and can serve as an entry point for more serious malware through the advertising networks it connects to.
Threat Profile
| Attribute | Details |
|---|---|
| Threat Family | Adware / Potentially Unwanted Program (PUP) |
| Classification | Adware:Win32/Montiera.B (Microsoft Defender), PUP.Optional.Montiera (Malwarebytes) |
| Aliases | Adware.Montiera.B, Win32/Montiera, PUP.Montiera |
| Platform | Windows 7, 8, 8.1, 10, 11 (32-bit and 64-bit) |
| Target Browsers | Chrome, Firefox, Edge, Internet Explorer |
| First Documented | 2014–2015 (peak activity 2015–2017) |
| Distribution Method | Software bundling, fake updates, misleading download buttons |
| Persistence Mechanisms | Registry Run keys, Scheduled Tasks, browser extensions, AppData folder installations |
| Primary Payload | Ad injection, browser hijacking, search redirection, tracking cookies |
| Typical File Locations | %LOCALAPPDATA%\[random folder], %APPDATA%\[random folder], Program Files\[deceptive name] |
| Network Behavior | Connects to ad networks, affiliate tracking domains, potentially malicious content delivery networks |
| Data Collection | Browsing history, search queries, clicked links, system information |
| Removal Difficulty | Moderate (multiple components, browser hijacking requires manual cleanup) |
How It Spreads
Montiera.B relies almost exclusively on social engineering rather than technical exploits. The most common infection vector is software bundling, where the adware hides inside the installation package of legitimate free software. Users who rush through installation wizards using "Express" or "Recommended" settings unknowingly agree to install Montiera.B alongside the program they actually wanted. The bundling is often disclosed in dense legal text or pre-checked opt-in boxes that most people never notice.
Another prevalent distribution method involves fake update notifications. Users visiting questionable streaming sites or file-sharing platforms encounter pop-ups claiming their Flash Player, Java, or media codec is out of date. Clicking "Update Now" downloads an installer that bundles Montiera.B with little or no legitimate software. These fake updates are particularly effective because they mimic legitimate update prompts closely enough to fool non-technical users.
Malicious advertising (malvertising) on otherwise legitimate websites also contributes to infections. Compromised ad networks serve banners with deceptive "Download" or "Play" buttons that trigger Montiera.B installers instead of the promised content. Some variants have been distributed through:
- Free software download sites that repackage installers with adware (particularly media players, PDF converters, and system "optimizers")
- Fake browser extension offers promising enhanced security, ad blocking (ironic), or video downloading capabilities
- Torrent bundles where executable files are disguised as video codecs or cracks for commercial software
- Email attachments posing as document readers or system utilities (less common for this family)
- Compromised installer mirrors for popular freeware, where attackers replace legitimate downloads with bundled versions
What It Does On Your Machine
Once Montiera.B executes, it immediately begins modifying your system to ensure persistence and revenue generation. The adware drops multiple components across your hard drive, typically creating randomly named folders in %LOCALAPPDATA% or %APPDATA% that contain executable files, DLL libraries, and configuration data. These components work together to inject advertisements into web pages you visit, even on sites that normally don't display ads or that you've previously viewed ad-free.
Browser hijacking is a core capability. Montiera.B installs extensions (often without appearing in your browser's extension list through manipulation of policy files) and modifies browser shortcuts to launch with specific command-line parameters. Your default search engine gets changed to a Montiera-controlled search portal that looks similar to Google or Bing but injects sponsored results at the top of every query. The homepage and new tab settings get redirected to advertising-laden landing pages. Even when you manually reset these settings, Montiera.B's persistence mechanisms restore the hijacked configuration within minutes or after reboot.
The adware aggressively monitors your browsing activity to build an advertising profile. It tracks which websites you visit, what search terms you enter, which links you click, and how long you spend on each page. This data gets transmitted to remote servers to optimize ad targeting. While Montiera.B isn't typically classified as spyware (it doesn't steal passwords or financial data directly), the behavioral tracking represents a significant privacy violation. The collected data may be sold to third-party advertisers or data brokers.
Performance degradation is inevitable. Montiera.B consumes CPU cycles to inject ads into web pages in real-time, uses memory to run background processes, and saturates network bandwidth by loading advertising content from dozens of different servers. Browsers become sluggish, page load times increase noticeably, and systems with limited RAM may experience frequent freezing. The constant background activity also reduces battery life on laptops.
Manual Removal — Step by Step
Disconnect from the Internet
Unplug your Ethernet cable or disable Wi-Fi before proceeding. This prevents Montiera.B from downloading additional components, communicating with command servers, or re-installing itself from remote sources during the removal process. Some adware variants can detect removal attempts and trigger reinstallation routines if still connected.
Boot Into Safe Mode with Networking
Restart your computer and press F8 repeatedly during boot (on Windows 7) or hold Shift while clicking Restart from the Start menu (Windows 8/10/11), then navigate to Troubleshoot > Advanced Options > Startup Settings > Restart > press 5 for Safe Mode with Networking. This loads Windows with minimal drivers and prevents Montiera.B's startup items from launching, making removal significantly easier.
Identify and Terminate Active Processes
Press Ctrl+Shift+Esc to open Task Manager. Look for suspicious processes with random names, high memory usage, or names containing "montiera", "updater", "service", or alphanumeric strings. Right-click each suspicious process, select "Open file location" to note where it's running from, then choose "End task". Document these locations—you'll need to delete the files shortly.
Uninstall Suspicious Programs
Open Control Panel > Programs and Features (or Settings > Apps on Windows 10/11). Sort by "Installed On" date and look for unfamiliar programs installed around the time your problems started. Uninstall anything with "Montiera", generic names like "PC Optimizer", "Browser Helper", "Ad Blocker" (ironic), or programs from unknown publishers. Some adware uses names that sound legitimate—when in doubt, Google the program name before uninstalling.
Remove Persistence Mechanisms
Press Win+R, type "regedit", and navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run. Delete any entries referencing montiera or pointing to the executable paths you noted earlier. Next, press Win+R, type "taskschd.msc", and delete any scheduled tasks with suspicious names or that reference the Montiera folders. Check startup folders at %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup for malicious shortcuts.
Delete Adware Files and Folders
Open File Explorer and navigate to %LOCALAPPDATA%, %APPDATA%, and %PROGRAMFILES%. Delete any folders you identified earlier that contain Montiera components. Common locations include folders with GUID names (long strings of letters/numbers in curly braces), folders named after the adware, or recently created folders with generic names. You may need to enable "Show hidden files" in View options. Some files may resist deletion—reboot into Safe Mode again if you encounter "file in use" errors.
Clean Browser Extensions and Settings
For each installed browser, access the extensions/add-ons page (chrome://extensions/, about:addons in Firefox, edge://extensions/) and remove any unfamiliar extensions, especially those installed recently or lacking a reputable publisher. Reset your homepage, search engine, and new tab settings to your preferences. In Chrome, check chrome://policy/ for forced policies—if present, you'll need to delete policy files from C:\Program Files\Google\Chrome\Application\[version]\default_apps or similar locations. For thorough cleanup, consider resetting the browser entirely through settings (you'll lose customizations but keep bookmarks if synced).
Run Reputable Anti-Malware Scanners
Reconnect to the internet and download Malwarebytes Free (malwarebytes.com). Run a full "Threat Scan" and quarantine everything it finds. Follow up with a scan using your primary antivirus if it's a reputable solution (Microsoft Defender, Bitdefender, Kaspersky, etc.). Even if you think you've manually removed everything, scanners often catch remnants, registry entries, or related PUPs that came bundled with Montiera.B. Update both tools before scanning to ensure the latest detection definitions.
Clear Browser Data and DNS Cache
In each browser, clear browsing data including cache, cookies, and site data for "All time" to remove tracking cookies and cached ad content. Press Win+R, type "cmd", and run "ipconfig /flushdns" to clear DNS cache—adware sometimes poisons DNS settings to redirect legitimate domains. Restart your router if you suspect DNS hijacking extended beyond your computer to network-level settings.
Reboot and Verify Clean System
Restart your computer normally (not Safe Mode) and monitor behavior for 24-48 hours. Check Task Manager for suspicious processes, verify browser settings remain as you configured them, and confirm no unauthorized extensions reappear. Visit a few regular websites to ensure ads display normally (not excessively). If problems persist, Montiera.B may have installed a rootkit component or other adware came bundled with it—at that point, professional removal is recommended to avoid incomplete cleaning that wastes your time.
Prevention
- Download software only from official sources. Avoid third-party download sites that repackage installers with bundled adware. Get programs directly from the developer's website or the Microsoft Store. If you must use a download portal, choose reputable ones like Ninite or FileHippo that explicitly reject bundled software.
- Always choose Custom/Advanced installation. Never click through with Express or Recommended settings. Read each screen carefully and deselect any pre-checked boxes offering "additional software", "browser enhancements", or "recommended tools". Legitimate software doesn't hide other programs in its installer—if you encounter bundled offers, reconsider whether the main program is trustworthy.
- Keep software and operating systems updated. Enable automatic updates for Windows and all installed programs. Many exploits that download PUPs target outdated software vulnerabilities. Browser updates particularly matter since they include security patches against malicious extensions and drive-by downloads.
- Use a reputable ad blocker. Extensions like uBlock Origin (not just "Adblock") prevent malicious ads from loading in the first place, closing a major infection vector. They also reduce exposure to fake download buttons and deceptive ads that trick users into installing adware.
- Maintain active antivirus with real-time protection. Windows Defender is adequate for most users if kept updated, but consider Bitdefender, Kaspersky, or similar if you frequently download free software. Enable real-time protection and cloud-delivered protection to catch threats before they execute. Supplement with periodic Malwarebytes scans.
- Be skeptical of update prompts. Legitimate software updates through built-in updaters or Windows Update, not random website pop-ups. If you see an "update required" message while browsing, close the page and manually check for updates through the program's official settings if concerned. Flash Player is dead (discontinued 2020)—any Flash update prompt is malicious.
- Review installed programs monthly. Check Programs and Features for unfamiliar entries. Adware often enters through bundled installers you forgot about. Prompt removal when programs appear unexpectedly prevents them from establishing deep persistence.
- Create a non-admin user account for daily use. Administrative privileges allow PUPs to install system-wide and modify protected locations. Running as a standard user forces installation prompts where you can decline suspicious software. Use your admin account only when intentionally installing trusted programs.
Bring It In
Manual removal works for technically confident users who have the time and patience to hunt through folders, registry keys, and browser settings. But if you've followed these steps and still see pop-ups, or if you'd rather have an expert handle it the first time, we're here in Roswell at 1735 Woodstock Road. Adware removal typically takes us 30-60 minutes depending on how deep the infection runs, and we'll check for any bundled malware that rode in with Montiera.B. We frequently find secondary infections—browser hijackers, cryptocurrency miners, or data-stealing trojans—that users didn't realize were present.
Call us at (770) 637-1435 to schedule a same-day appointment, or just stop by during business hours. We'll diagnose the infection for free and give you an upfront price before starting any work. Most adware cleanings run $89-$129 depending on severity, and that includes our 90-day warranty, browser optimization, and security recommendations tailored to your computing habits. Don't let adware turn your computer into an advertising billboard—bring it in and we'll get your machine running clean and fast again.