Do you ever receive emails containing attachments? It might be an entertaining forward from a trusted friend, or the message might simply be a tempting offer from an unknown source. Either way, you would be wise to avoid all email attachments unless you are absolutely sure of their origin, because this is a common method of transmitting Zero Day Trojan viruses.
The problem with Zero Day Trojans is that hackers use them to exploit as-yet-undiscovered (by software developers) holes in your system’s security. Until developers realize that these holes exist, and release a patch to fix the problem, they can be used to gain access to your computer and all files contained within it.
Let’s assume you receive an email forward from a friend, promising funny pictures of animals performing ridiculous antics. You’re bored at work and you could use a laugh. And your antivirus program is running. What could be the harm in opening the email’s attached files?
As it turns out, there could be plenty of harm! Keep in mind how a Zero Day Trojan works: It exploits security issues that are currently unknown to software developers. If the people who developed your system’s software don’t know these problems exist, then neither do the people who created your antivirus program! And what an antivirus program cannot detect, it often cannot prevent or remove from your computer.
Zero Day vulnerabilities used to be a rare occurrence. But now that such a large market for buying and selling these types of exploits has emerged, mostly driven by government intelligence agencies, we are seeing a drastic increase in these problems.
Rather than relying solely on your antivirus program, take a proactive approach to Zero Day vulnerabilities. Avoid putting yourself at risk in the first place, and you stand a better chance of preventing this type of Trojan virus from infecting your machines.