I recently had a case of a hijacked Default Browser message (the one that asks you to set the browser as default) in Internet Explorer (IE) 11 on a Windows 8.1 machine. Now that is not to say that it cannot happen to other versions of Windows, Internet Explorer or even other browsers, but this fix will clear the Internet Explorer issue.
With many of these things, the cause of this is malware, and the user doing or rather installing or running something they shouldn’t be (what they wanted the software for was perfectly OK, its just they got stung by the malware).
Anyway the issue presented like this;
IMPORTANT NOTE: Now first things first. DO NOT click on any of the links in the page. It is also important to note that even if Internet Explorer is the default browser, or you have told it not to bother you, it will still appear.
Now the first step in this is understanding what has happened, which in this case is that the iframe.dll file has be hijacked, either through modification or replacement (which indicates that the program would have had to have gone through UAC and the user OK’ing the change), specifically it seems that the page is being redirected, but I cannot confirm this as it was more important to fix the issue than it was to find out the technical reasons why
None the less the first step is to run a malware cleaner, specifically I use Malwarebytes, and I did a cleanup of the system with CCleaner for good measure, but it is important to note that this is just to clean up other things that the malware may have left behind, it is not to fix this problem.
As this problem resides in what is a reasonably well protected file, the best way to fix the issue is with Microsoft’s built-in System File Checker (SFC) tool.
It is actually rather simple to fix this error;
Open a Command Prompt window as Administrator
Once you are in the command prompt type;
This tool will now run and verify the files Microsoft has put into the system to validate they are the correct files, if they are not and have been replaced or otherwise modified, it will replace them with the original file. This process may take some time depending on the hardware you are running it on
Once complete, you need to restart the PC, and the SFC tool tells you as much
Restart your PC and the offending window will now be replaced with the default Microsoft one. Now how I said before it seems to override/overwrite the setting telling Internet Explorer not to display the defaultbrowser.htm tab (either because it is default, or you have told it not to check). This continues on here, because that setting was tampered with by the malware it will display the default browser page, to clear this you either simply need to tell it to not display it, or go through the set as default process.