ISTbar ads: what it is and how to remove it
ISTbar is an application also known as Adware.Istbar because it is a malicious Internet Explorer search toolbar that hijacks a web browser by changing its default start page and modifying related settings. It also adds numerous bookmarks leading to advertising resources, displays undesirable pop-up advertisements and pornographic content.
Facts checked October 7, 2026. Removal steps tested on Windows 11 (26H2) and checked against Microsoft's and the browser makers' current documentation. Sections marked as our earlier report are the original text: they describe the threat as it was then and have not been reviewed since. The 2026 status, the removal steps and the questions are current.
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ISTbar ads: summary
| Distribution | Freeware installations, other PUPs, deceptive content |
|---|---|
| Name | ISTbar |
| Type | PUP, adware, hijacker |
| Issues | The program triggers redirects and other issues with the machine, internet, browsing activities |
| Detection names | No Microsoft detection name is known |
| Damage | Not recorded in the old report |
| Removal | Scan the PC with security software to find and remove the malware and anything installed with it. Fortect scans Windows for malware and repairs the system files and settings it damaged. Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free. |
Show 5 more facts
| Symptoms | An unknown program in Installed apps |
|---|---|
| Evidence | One write-up by a security site; details still limited |
| Program | ISTbar |
| First seen | 19 April 2021 |
| Facts checked | 7 October 2026 |
Is ISTbar ads dangerous?
From our report of Apr 2021 · not reviewed since
ISTbar is the questionable browser piece that gets installed behind your back
ISTbar is an application also known as Adware.Istbar because it is a malicious Internet Explorer search toolbar that hijacks a web browser by changing its default start page and modifying related settings. It also adds numerous bookmarks leading to advertising resources, displays undesirable pop-up advertisements and pornographic content.
The program is considered unwanted or even potentially dangerous due to third-party content and various sponsors that deliver their material to your screen with the help of the hijacker. You shouldn't keep the program running on the machine, so the guide below with all the browser resetting and other methods shows how to clear the application off of the device.
The PUP downloads and installs multiple third-party adware and spyware parasites without asking for user permission. It has the ability to silently update itself via the Internet. ISTbar is usually installed by some infamous advertising and pornographic websites. This is why it is called a PUP or PUA because it comes without users' permission.
The parasite automatically runs on every Windows startup and can alter various settings or preferences. It places its files on the Windows registry, and it is quite hard to find all these files and delete them in order to remove this computer parasite.
You shouldn't keep such programs on the machine, even when you install the program yourself because it gives no value to your time on the internet. If you receive the suspicious detection alert or a warning about this program or another intruder, you must remove the application properly, so you can avoid issues with the performance in the future.

From our report of Apr 2021 · not reviewed since
More from our earlier report on ISTbar
- Some PUPs can trigger issues with general performance, so run a tool like and recover those files or altered pieces
How ISTbar ads got into your browser
From our report of Apr 2021 · not reviewed since
Browser hijackers, adware, or different browser-based applications are commonly distributed as a software attachment, but you can also accidentally install it if you tend to browse through unreliable websites.
As we have already mentioned, it can be distributed on various porn websites; also, it can be sent by mail.
To prevent the silent installation of an intruder like this, you need to be careful when surfing the web. Do not open Spam or Junk emails and do not download the attachments from such e-mails. Also, be attentive while installing new programs. Make sure you choose Advanced or Custom installation mode and then untick the agreement to install anything unknown.
How to remove ISTbar ads
How to remove the ISTbar extension
Do the browser steps in every browser and profile on the PC, then check Windows for the program that installed the extension.
Step 1: Remove extensions you did not add
In Chrome open
chrome://extensions, in Edgeedge://extensions, and in Firefox the menu > Extensions and themes.Remove every extension you do not remember adding, especially search, new tab, coupon, PDF, weather or video downloader add-ons. Check every browser and every profile, because each keeps its own list.
If an extension has no Remove button or comes back, a browser policy holds it (see "Managed by your organization" in the procedure below). The pages are the same on Windows 11 and Windows 10.

Chrome on Windows 11: More > Extensions > Manage extensions. Full procedure with screenshots: Remove a browser extension
Step 2: Uninstall ISTbar
ISTbar is removed like any other program, from the list of installed apps. In Windows 11 that is Settings > Apps > Installed apps, in Windows 10 Settings > Apps > Apps & features, and in both you can also use Control Panel > Programs and Features.
Select ISTbar, click Uninstall and follow the uninstaller to the end. Then look at the entries just above and below it when the list is sorted by date: bundled programs install at the same minute.
Full procedure with screenshots: Uninstall a program or app in Windows On uGetFix
Step 3: Reset the browser
A reset removes what the steps above could miss:
- changed start pages
- site permissions
- hidden settings
In Chrome open Settings > Reset settings > Restore settings to their original defaults; in Edge Settings > Reset settings; in Firefox Help > More troubleshooting information > Refresh Firefox.
Tip: Bookmarks and saved passwords stay, while extensions are turned off and the search engine and start page return to the defaults.
Reset every browser on the PC, including Edge, which Windows 11 and Windows 10 always have.

Chrome on Windows 11: Settings > Reset settings. Full procedure with screenshots: Reset a browser and fix a hijacked search engine
Step 4: Scan the PC, then run the offline scan
A scan finds the parts of ISTbar that the manual steps cannot see. In Windows Security > Virus & threat protection > Scan options, start a Full scan and quarantine what it reports.
Follow it with Microsoft Defender Antivirus (offline scan) > Scan now, which restarts the PC and checks the disk while Windows and the malware are not running.
It takes about 15 minutes and works the same in Windows 11 and Windows 10. If either scan finds something, run the full scan again after removal until it comes back clean.

Windows 11: Windows Security > Virus & threat protection > Scan options. Full procedure with screenshots: Run a Microsoft Defender Offline scan
Instructions for each browser and system
The detailed steps for every browser and system this guide covers. Open the one you use.
Uninstall from Windows
Uninstall from Windows 10/8:
- Type Control Panel into the Windows search box and open the result.
- Under Programs, select Uninstall a program.

Uninstall from Windows 7/XP:
- Click on Windows Start > Control Panel (Windows XP users should click on Add/Remove Programs).
- In Control Panel, select Programs > Uninstall a program.

Remove the unwanted program:
- In the Programs and Features window, look for any recently installed suspicious entries, select them, and click Uninstall.
- If User Account Control appears, click Yes to confirm, then complete the removal.

Remove from Google Chrome
Delete malicious extensions from Google Chrome:
- Open Google Chrome, click on the Menu (three vertical dots at the top-right corner) and select More tools > Extensions.
- In the newly opened window, you will see all the installed extensions. Uninstall all suspicious extensions related to the unwanted program by clicking Remove.

Clear cache and web data from Chrome:
- Click on Menu and pick Settings.
- Under Privacy and security, select Clear browsing data.
- Select Browsing history, Cookies and other site data, as well as Cached images and files.
- Click Clear data.

Change your homepage:
- Click menu and choose Settings.
- Look for a suspicious site in the On startup section.
- Click on Open a specific or set of pages and click on three dots to find the Remove option.
Reset Google Chrome:
If the previous methods did not help you, reset Google Chrome to eliminate all the unwanted components:
- Click on Menu and select Settings.
- In the Settings, scroll down and click Advanced.
- Scroll down and locate Reset and clean up section.
- Now click Restore settings to their original defaults.
- Confirm with Reset settings.

Remove from Microsoft Edge
Delete unwanted extensions from MS Edge:
- Select Menu (three horizontal dots at the top-right of the browser window) and pick Extensions.
- From the list, pick the extension and click on the Gear icon.
- Click Remove.

Clear cookies and other browser data:
- Click on the Menu (three horizontal dots at the top-right of the browser window) and select Settings > Privacy, search, and services..
- Under Clear browsing data, pick Choose what to clear.
- Select Cookies and other site data and Cached images and files. (apart from passwords, although you might want to include Media licenses as well, if applicable) and click on Clear.

Restore new tab and homepage settings:
- Click the menu icon and choose Settings.
- Then find On startup section.
- Click Remove next to any suspicious startup page.
Reset MS Edge if the above steps did not work:
- Press on Ctrl + Shift + Esc to open Task Manager.
- Click on More details arrow at the bottom of the window.
- Select Details tab.
- Now scroll down and locate every entry with Microsoft Edge name in it. Right-click on each of them and select End Task to stop MS Edge from running.

Delete extensions from MS Edge (Chromium):
- Open Edge and click select Settings > Extensions.
- Delete unwanted extensions by clicking Remove.

Clear cache and site data:
- Click on Menu and go to Settings.
- Select Privacy, search and services.
- Under Clear browsing data, pick Choose what to clear.
- Under Time range, pick All time.
- Select Clear now.

Reset Chromium-based MS Edge:
- Click on Menu and select Settings.
- On the left side, pick Reset settings.
- Select Restore settings to their default values.
- Confirm with Reset.
- This will disable extensions and reset startup pages but will not delete bookmarks, saved passwords, or browsing history.

Remove from Mozilla Firefox (FF)
Remove dangerous extensions:
- Open Mozilla Firefox browser and click on the Menu (three horizontal lines at the top-right of the window).
- Select Add-ons.
- In here, select the unwanted extension and click Remove.

Reset the homepage:
- Click three horizontal lines at the top right corner to open the menu.
- Choose Settings.
- Under Home, set your preferred homepage and new tab settings.
Clear cookies and site data:
- Click Menu and pick Settings.
- Go to Privacy & Security section.
- Scroll down to locate Cookies and Site Data.
- Click on Clear Data...
- Select Cookies and Site Data and Temporary cached files and pages, then click Clear.

Reset Mozilla Firefox
If clearing the browser as explained above did not help, reset Mozilla Firefox:
- Open Mozilla Firefox browser and click the Menu.
- Go to Help and then choose Troubleshooting Information.

- Under Give Firefox a tune up section, click on Refresh Firefox...
- Once the pop-up shows up, confirm the action by pressing on Refresh Firefox.

Delete from Safari
Remove dangerous extensions:
- Open Safari, click Safari in the menu at the top-left of the screen, and select Preferences.
- Go to the Extensions tab, look for any suspicious entries, and click Uninstall to remove them.

Clear history and website data:
- Click Safari in the menu and pick Clear History.
- Set Clear to all history and confirm with Clear History.

Reset Safari:
- Click Safari in the menu and select Preferences > Advanced.
- Enable Show Develop menu in menu bar.
- From the menu bar, click Develop and select Empty Caches.

Delete from macOS
Remove the unwanted application:
- From the menu bar, select Go > Applications.
- In the Applications folder, look for any suspicious entries, then drag them to Trash (or right-click and pick Move to Trash).

Delete leftover files and folders:
- Select Go > Go to Folder.
- Enter /Library/Application Support and remove any suspicious folders related to the unwanted program.
- Repeat the same check in the /Library/LaunchAgents and /Library/LaunchDaemons folders, deleting any suspicious entries.

- Finally, empty the Trash to permanently remove the leftovers.
Do not let government spy on you
The government has many issues in regards to tracking users' data and spying on citizens, so you should take this into consideration and learn more about shady information gathering practices.
Avoid any unwanted government tracking or spying by going totally anonymous on the internet.
You can choose a different location when you go online and access any material you want without particular content restrictions. You can easily enjoy internet connection without any risks of being hacked by using VPN.
Control the information that can be accessed by government any other unwanted party and surf online without being spied on. Even if you are not involved in illegal activities or trust your selection of services, platforms, be suspicious for your own security and take precautionary measures by using the VPN service.
Backup files for the later use, in case of the malware attack
Computer users can suffer from data losses due to cyber infections or their own faulty doings.
Ransomware can encrypt and hold files hostage, while unforeseen power cuts might cause a loss of important documents. If you have proper up-to-date backups, you can easily recover after such an incident and get back to work. It is also equally important to update backups on a regular basis so that the newest information remains intact - you can set this process to be performed automatically.
When you have the previous version of every important document or project you can avoid frustration and breakdowns. It comes in handy when malware strikes out of nowhere. Use for the data restoration process.
From our report of Apr 2021 · not reviewed since
Make sure to clear the system fully and remove the PUP
ISTbar virus can be deleted manually, but you can check the manual removal method below this article - and you will see that it is very complicated to do and might take a long time to remove it entirely.
To delete ISTbar completely, you should use a professional removal tool, so all the files get terminated. So you should install an anti-malware or security tool and run a full system scan with it. Once the machine is virus-free and you double-checked, run the tool for the system repair and recover any affected files.
Questions about ISTbar ads
What is ISTbar and why is it on my PC?
ISTbar is a program that was installed on the PC, most likely together with something else you downloaded. Free software sites and many installers add extra programs on setup pages with pre-ticked boxes, so the extra install looks like your choice even though nobody read the page.
Check the install date in Settings, Apps, Installed apps: the program you installed that day is the probable carrier. If you do not need ISTbar, uninstall it. If it belongs to your hardware or to a program you use, search its exact name and publisher first, because drivers and their tools can have unfamiliar names.
ISTbar will not uninstall. What can I do?
First restart the PC and try again, because the program may have been running and locked its own files. If the uninstaller is missing or fails, start Windows in Safe Mode, where most third-party programs do not start, and remove ISTbar from Installed apps there.
If it still refuses, delete its startup entry and its scheduled task, restart, and try once more. A program that actively prevents removal is behaving like malware, so finish with a Microsoft Defender offline scan. Avoid third-party uninstallers offered on search ads; several of them are unwanted programs themselves.
An ad showed a phone number and I called it. What now?
The number belongs to scammers, not to Microsoft or an antivirus company. If you only talked, hang up and do not call back. If you let them connect to the PC, disconnect it from the internet, uninstall the remote access program they used, such as AnyDesk, TeamViewer, ScreenConnect or UltraViewer, and run a full and offline scan.
If you paid or gave bank details, call your bank at once on the number printed on your card. Change any passwords you typed while they were connected, and report the call.
Why didn't my antivirus catch ISTbar?
Many security products do not block adware or notification sites by default, because users often agreed to them, even through a misleading prompt. Notification spam installs nothing at all, so there is no file to detect.
In Windows 11 you can make Microsoft Defender block potentially unwanted apps: open Windows Security > App & browser control > Reputation-based protection settings and turn on Potentially unwanted app blocking. If notifications caused the pop-ups, no scanner will report them; the fix is in the browser's site settings.
I clicked on one of the ads. Am I infected?
Probably not. Clicking an ad usually only opens a page, and a page cannot install programs on an up-to-date Windows PC without your help.
You are at risk only if you then downloaded and ran a file, allowed notifications, entered card or login details, or called a phone number shown on the page. Delete any download and run a full and offline scan.
Change passwords you typed, from a clean device. Call your bank if you gave card details. If you called a number or allowed remote access, see the next question.
Can adware slow down my PC?
Yes. Adware runs in the background, loads ad scripts, opens extra tabs and contacts its servers, all of which use processor time, memory and bandwidth. Ad-heavy extensions also slow down every page, because they inspect and change it before you see it.
The effect is strongest on older PCs and when several adware programs arrived together. After removal, restart the PC and check Task Manager for anything still using a lot of resources that you do not recognise. Speed usually returns to normal once the ads stop.
Does adware steal passwords?
Ordinary adware is built to show ads, not to steal logins, and most of it never touches saved passwords. The line is blurry, though. Extensions that can read every page could capture what you type, and adware ads sometimes lead to phishing pages that ask for passwords directly.
If you entered credentials on a page reached through an ad, change that password from a clean device and turn on two-step verification. Otherwise, removing adware extension and clearing cookies is usually enough.
Is ISTbar a virus?
Not in the strict sense: ISTbar is unwanted software, classed here as an adware extension, not a self-copying virus. Security programs often label such software as adware, a potentially unwanted program or a browser hijacker.
It still needs removal, because it changes browser settings, shows ads and can lead you to unsafe pages. The larger risk is clicking an ad that leads to a fake update or scam page.
Will Fortect remove ISTbar?
Fortect scans Windows for malware and unwanted programs and repairs the system files and settings they change, and its free scan shows what it finds on your PC before you decide anything.
For ISTbar, follow the plan above as well: the browser steps take back permissions and settings that no scanner treats as a threat, and uninstalling the program that brought it removes the source.
Run Microsoft Defender's full scan and, if anything was found, its offline scan as a second opinion. If the symptoms are gone after the plan and both scans are clean, there is nothing more to do.
Sources
- Google Chrome Help: Use notifications to get alerts (no longer online) (read October 7, 2026)
- FTC: How to recognize, remove and avoid malware (read October 7, 2026)
- Microsoft Learn: Microsoft Defender Offline (read October 7, 2026)
- Microsoft Learn: How Microsoft names malware (read October 7, 2026)