The latest threat report from BitDefender shows that top of the nasty parade for March was a USB Trojan.

Known by the tag Trojan.Autoruninf.Gen, it accounted, says BitDefender, for 13% of total global malware in March. Trojan.Autoruninf.Gen is a mechanism of a generic nature which is designed to spread via removable drives. It exploits an established vulnerability when people swap files using physical devices such as memory sticks.

Number two in March was that old favourite the Conficker, or Kido as its otherwise known. Although at 6% of total global malware in March less than half the threat posed by Trojan.Autoruninf.Gen, it is still being a nuisance and hanging around. Its trick is to exploit a Microsoft Windows vulnerability and to get rid of it, users have to update their operating system and ensure that their anti virus software is up to date.

In third is another old favourite, one which gets hold of Adobe’s PDF Reader’s JavaScript engine and uses it to piggy back malicious code into a computer. It’s known as Exploit.PDF-JS.Gen and it’s a nasty piece of work which uses a very commonly used application.

But talking of nasties, in fourth is one that takes the biscuit. It’s a file infector known as Win32.Sality.OG. What’s makes this family of infectors so bad, is that it’s protected by a polymorphic code, which makes it extremely difficult to firstly detect and then remove. What’s more, the rootkit part of the virus does its best to disable antivirus applications on the computer its attacking. One to be avoided at all costs.

In at number five this is the Trojan.JS.Downloader.BIO. Inserted into legimate webpages via SQL injection methods and tactics, this is actually JavaScript. It only targets those websites built with ASP. Another characteristic of Trojan.JS.Downloader.BIO. is that is forms cookies from bits of information about a victim’s browsing habits which are then sent to a website based in China.

That’s the top five, but here’s the complete BitDefender run for March:

1. Trojan.AutorunINF.Gen 13,40
2. Win32.Worm.Downadup.Gen 6,19
3. Exploit.PDF-JS.Gen 5,30
4. Win32.Sality.OG 2,58
5. Trojan.JS.Downloader.BIO 2,13
6. Trojan.Autorun.AET 1,95
7. Gen:Heur.Krypt.21 1,921
8. Worm.Autorun.VHG 1,78
9. Exploit.PDF-Payload.Gen 1,67
10. Trojan.Wimad.Gen.1 1,42.

Guest Article by Neil Camp