How to remove the DyFuCA_BH Module malware

Most antivirus programs classify wsem303.dll as a harmful extension to Internet Explorer: e.g. Trojan-Downloader.Win32.Dyfuca.dt (detected by Kaspersky), and Adware:Win32/Avenuemedia (detected by Microsoft). Add-ons like this can display ads, slow down your computer and cause various other errors. If you can't remember installing the associated DyFuCA_BH Module software, it's no surprise. In most cases, this kind of adware is installed on the side when you install a freeware product like a Youtube Downloader or a PDF Converter. In the following selection, you can read more about DyFuCA_BH Module and how to get rid of it.

Click here to automatically remove the DyFuCA_BH Module malware

Wsem303.dll file information

The process known as DyFuCA_BH Module belongs to software DyFuCA_BH Module by Avenue Media N.V (

Description: Wsem303.dll is not essential for Windows and will often cause problems. The wsem303.dll file is located in the C:\Windows folder. The file size on Windows 10/8/7/XP is 63,232 bytes. 
This .dll file is a Browser Helper Object (BHO) that runs automatically every time you start your web browser. BHOs are not stopped by personal firewalls, because they are identified by the firewall as part of the browser itself. BHOs are often used by adware and spyware. IDs used by this BHO include 8F4E5661-F99E-4B3E-8D85-0EA71C0748E4. The program is not visible. The wsem303.dll file is able to monitor web browsers. The service has no detailed description. It is not a Windows core file. The wsem303.dll file is digitally signed. Therefore the technical security rating is 62% dangerous, however you should also read the user reviews.

Recommended: Identify wsem303.dll related errors

External information from Tony Klein:

Important: You should check the wsem303.dll process on your PC to see if it is a threat. If DyFuCA_BH Module has changed your browser's search engine and start page, you can recover your browser's default settings as follows:

Reset default browser settings for Internet-Explorer ▾
  1. In Internet Explorer, press the key combination Alt + X to open the Tools menu.
  2. Click Internet options.
  3. Click the Advanced tab.
  4. Click the Reset... button.
  5. Enable the Delete personal settings option.
This will reset your Internet Explorer to its default settings. Your browser will start with the familiar start page and search engine—without popups, ads, cookies, but all browser add-ons are deleted too [1]. Make cleaning up your browser and your computer simpler and safer with Security Task Manager.


User Comments

i removed it from my pc because it contained a virus but my msn messanger doesn't work anymore so is this a needed dll file for xp or just a virus?
  eddy seven  
Part of internet optimizer - spyware basically
Disguises itself as another program in the task bar so I am having trouble stopping the process and deleting the file.
Norton AntiVir 9 had found the wsem303.dll in \system32. To Delete it, we had to kill als svchost.exe's, then we can delete it by securityTaskManager.
  David G.   (further information)
this file is linked with a spyware as it was shown on my PC "istsvc.exe" and there is more files with it to work out they gives u a pop-up window each time u r surfing the net
If running win2k you can easily remove it in safe mode just delete it and empty recycle bin
  Dan Hinds systems Admin.  
Infected with Trojan.Downloader.Dyfuca.DD (reported from BitDefender Online Scanner 8).
you think i should delete this file and "istsvc.exe"?

Rating chart

Summary: Average user rating of wsem303.dll: based on 9 votes with 9 user comments. One user thinks it's neither essential nor dangerous. 4 users suspect danger. 4 users think wsem303.dll is dangerous and recommend removing it. 2 users don't grade wsem303.dll ("not sure about it").

Do you have additional information?
What do you know about wsem303.dll:
How would you rate it:
Link for more info:
Your Name:

Best practices for resolving wsem303 issues

The following programs have also been shown useful for a deeper analysis: Security Task Manager examines the active wsem303 process on your computer and clearly tells you what it is doing. Malwarebytes' well-known anti-malware tool tells you if the wsem303.dll on your computer displays annoying ads, slowing it down. This type of unwanted adware program is not considered by some antivirus software to be a virus and is therefore not marked for cleanup.

A clean and tidy computer is the key requirement for avoiding PC trouble. 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.

Other processes

wsem303.dll [all]