In this case, it was bundled with BackupSetup.exe file. This was an installer file for rather popular free backup software. It can be distributed in other ways as well, for example via social networks and spam.
As mentioned, such malware infections are commonly spread via email attachments. The author will attach the file containing the malware to a mail and then spam hundreds or even thousands of people. And if you're unlucky enough that your name is on the list – one of them could be you.
Likewise if you've been sucked in to downloading something less than reputable – i.e. through social engineering – you may also find yourself on the receiving end installing of this malware.
If you do find you've been infected by MalSign.Generic.DE7, please follow the steps in the removal guide below or read how to Remove MalSign.Generic (Uninstall Guide). Scan your computer with anti-malware software and delete the questionable files. If you are unlucky enough, you may have to reinstall your operating system too, which is not fun. Therefore, it makes all the sense in the world to have a decent anti-malware installed and to exercise a little caution when opening emails.
If you have questions, leave a comment below. I will be more than happy to help you. Good luck and be safe online!
Written by Michael Kaur, http://deletemalware.blogspot.com
MalSign.Generic.DE7 Removal Guide:
1. First of all, download recommended anti-malware software and run a full system scan. It will detect and remove this infection from your computer.
2. Download and run TDSSKiller. Press the button Start scan for the utility to start scanning.
3. Wait for the scan and disinfection process to be over. Then click Continue. Please reboot your computer after the disinfection is over.