What is APNStub.exe?

The genuine APNStub.exe file is a software component of Ask Toolbar for Internet Explorer by
APNStub.exe is an executable file that is part of Ask Toolbar for Internet Explorer, an advertising-supported toolbar that lets users search for content on the Internet. This is not an essential process for Windows and can be disabled if known to create problems. Ask Toolbar for Internet Explorer is categorised as a PUP (potentially unwanted program) due to its ability to hijack the browser and display sponsored advertising. The program is very difficult to remove. The toolbar is often installed along with free programs that are downloaded from untrustworthy websites. The program collects leads (user details such as email addresses) for sponsorers and is specifically designed to generate money. is an American Internet company that offers a question answering-focused service and web search engine. The company has been criticised for misleading users into installing its browser toolbar that comes bundled with legitimate software, especially since the program is difficult to remove. was founded in 1996 and is currenly headquartered in Oakland, California, United States.

APNStub stands for Ask Partner Network Stub Application

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the APNStub.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

Click to Run a Free Scan for APNStub.exe related errors

APNStub.exe file information

Windows Task Manager with APNStub
APNStub.exe process in Windows Task Manager

The process known as AskStub Application belongs to software Avira AntiVir Personal - Free or Ask Toolbar for Internet Explorer by (

Description: APNStub.exe is not essential for the Windows OS and causes relatively few problems. APNStub.exe is located in a subfolder of "C:\Program Files". The file size on Windows 10/8/7/XP is 108,424 bytes. 
The program is not visible. It is a Verisign signed file. The file has a digital signature. It is not a Windows core file. Therefore the technical security rating is 31% dangerous.

Uninstalling this variant: If you encounter difficulties with APNStub.exe, you may also safely remove the program using the uninstall program of Avira AntiVir Personal - Free (Control Panel ⇒ Uninstall a Program).

Recommended: Identify APNStub.exe related errors

If APNStub.exe is located in the Windows folder for temporary files, the security rating is 22% dangerous. The file size is 358,600 bytes. The program is not visible. APNStub.exe is a Verisign signed file. It is digitally signed. The APNStub.exe file is not a Windows core file. APNStub.exe is able to monitor applications.

Uninstalling this variant: If you encounter difficulties with APNStub.exe, you may also turn to the software developer, ASK, for advice or safely remove the program using the uninstall program of Ask Toolbar for Internet Explorer (Control Panel ⇒ Uninstall a Program).

Important: Some malware camouflages itself as APNStub.exe, particularly when located in the C:\Windows or C:\Windows\System32 folder. Therefore, you should check the APNStub.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


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Best practices for resolving APNStub issues

A clean and tidy computer is the key requirement for avoiding problems with APNStub. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the APNStub.exe process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

APNStub.exe [all]