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Virus-writers are using increasingly complex and sophisticated techniques in their bid to circumvent antivirus software and disseminate their viruses. A case in point was the notorious Nimda virus that used multiple methods to spread itself and was based on an exploit rather than on the virus/trojan behavior for which antivirus products typically search. Antivirus software, though essential, cannot combat such threats alone; an email exploit detection tool is also necessary.

What is an exploit?

An exploit uses known vulnerabilities in applications or operating systems to execute a program or code. It ‘exploits’a feature of a program or the operating system for its own use, such as executing arbitrary machine code, read/write files on the hard disk, or gain illicit access.

What is an email exploit?

An email exploit is an exploit launched via email. An email exploit is essentially an exploit that can be embedded in an email, and executed on the recipient’s machine once the user either opens or receives the email. This allows the hacker to bypass most firewalls and antivirus products.

Difference between antivirus software and email exploit detection software

Antivirus software is designed to detect known malicious codes. An email exploit engine takes a different approach: it analyses the code for exploits that could be malicious. This means it can protect against new viruses, but most importantly against unknown viruses/malicious code. This is crucial as an unknown virus could be a one-off piece of code, developed specifically to break into your network.

Email exploit detection software analyzes emails for exploits – i.e., it scans for methods used to exploit the OS, email client or Internet Explorer – that can permit execution of code or a program on the user’s system. It does not check whether the program is malicious or not. It simply assumes there is a security risk if an email is using an exploit in order to run a program or piece of code.

In this manner, an email exploit engine works like an intrusion detection system (IDS) for email. The email exploit engine might cause more false positives, but it adds a new layer of security that is not available in a normal antivirus package, simply because it uses a totally different way of securing email.

Antivirus engines do protect against some exploits but they do not check for all exploits or attacks. An exploit detection engine checks for all known exploits. Because the email exploit engine is optimized for finding exploits in email, it can therefore be more effective at this job than a general purpose antivirus engine.

Exploit engine requires less updates

An exploit engine needs to be updated less frequently than an antivirus engine because it looks for a method rather than a specific virus. Although keeping exploit and antivirus engines up-to-date involve very similar operations, the results are different. Once an exploit is identified and incorporated in an exploit engine, that engine can protect against any new virus that is based on a known exploit. That means the exploit engine will catch the virus even before the antivirus vendor is aware of its emergence, and certainly before the antivirus definition files have been updated to counter the attack. This is a critical advantage, as shown by the following examples that occurred in 2001.

The Lessons of Nimda, Bad rans.B, Yaha and Bugbear

Nimda and BadTrans.B are two viruses that became highly known worldwide in 2001 because they infected a colossal number of Windows computers with Internet access. Nimda alone is estimated to have affected about 8.3 million computer networks around the world, according to US research firm Computer Economics (November 2001).

Why you need an email exploit detection engine


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