URGENT - ARE LATEST VERSIONS OF FIREFOX DOWNLOADS INFECTED WITH MALWARE/ADWARE?

Question

It is VERY URGENT that the following is looked into by Mozilla Firefox and anyone else who uses this browser, as it would appear that the latest installation downloads from Mozilla Firefox (GB-EN) for versions 28.0 and 29 (and quite possibly previous versions) ARE THEMSELVES INFECTED with malware/adware. This is the only conclusion I can come to after repeated resets of my computers to factory settings, and everything is fine until I re-download Mozilla Firefox and select it as default browser, then the following happens when my Office 365 account is accessed:
In Office 365, if I select the 'File' menu and 'Office Account', then click on the 'Manage Account' button, TWO tabs on the default browser (if it is Firefox) are opened and the SECOND tab is a malware/adware page, usually called something like www.74f.com or another URL or server with a number, and sometimes this has an email address on the adware page that opens. This only happens when Mozilla Firefox is the default browser - it does not happen in Internet Explorer. In IE, the second tab is the correct tab for the Account in Office 365.
This has caused me to do repeated resets to factory default settings on my two laptops, one running Windows 8.1 64 bit and one running Windows 7 64 bit, and everything is fine when re-installation of all programs is complete and IE is the default browser. As soon as Mozilla Firefox is downloaded - the latest versions 28 or 29, and Firefox is set as the default browser, the malware/adware tab reopens in Office 365, as above.
On doing a search on what www.74f.com is, it appears to be registered on servers in China.
The malware/adware seems to be directly connected with the download and installation of the latest versions of Firefox. PLEASE INVESTIGATE URGENTLY - as although Firefox has always been my favourite browser, there is no way I am ever going to use it again unless this is solved, as I am fed up with doing factory resets of my computers to solve this. Each time I re-install Firefox it happens again, to a previously clean system.

Answer 1

First - Relax
So to clarify what the issue is. What apparently no one of our IT experts could figure out in a YEAR!
If you trace everything with Procmon you will see that this is a simple issue of not putting Quotation marks around Command line arguments.
That is what Office is executing as you click that "Manage Account" button.
"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" http://o15.officeredir.microsoft.com/r/rlidOfficeManagementPortal?ver=15&app=outlook.exe&clid=111&p1=1&lidhelp=1111&liduser=1111&lidui=1111&MachineKey=11111-111-111111 66F
So there is a MachineKey generated with a space in it.
What happens if you execute this in cmd… Correct – Firefox will assume that 66F is a 2nd argument in this case a URL and translate it to www.66f.com after not finding a DNS record for 66F in the local environment.
Of course ChinaHackers will figure this out too and maybe use this… but then I couldn’t find anything strange with the 66f website.
As in this case: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" FirstTab 2ndTab
This is not a Firefox issue MS should just bloody put his Urls in Quotation marks!
"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" “http://o15.officeredir.microsoft.com/r/rlidOfficeManagementPortal?ver=15&app=outlook.exe&clid=111&p1=1&lidhelp=1111&liduser=1111&lidui=1111&MachineKey=11111-111-111111 66F”
Now feel free to write Microsoft and tell them thanks for wasting 15min of my day.