A report by Panda Software finds that the absence of large-scale virus epidemics has, once again, been the most notable characteristic of 2006. In fact, the list of frequently detected viruses during 2006 has varied little throughout the year.

However, this does not necessarily mean that there is a lower risk of infection. What is happening is that the attacks have become more silent and more specific, as they are increasingly motivated by financial gain.

"Despite what people may think," explains Luis Corrons, director, PandaLabs, "the risk of virus infection is greater than ever. Firstly, due to the strategy of simultaneously distributing numerous variants of a malicious code, as was the case with Bagle or Gaobot, thereby increasing the chances of infection, and secondly, because the majority of attacks are now financially motivated, and are therefore more discreet."

Panda Software has published the Top Ten of the viruses most frequently detected in 2006.

The first place on the list, for the second successive year, has been given to the Sdbot.ftp. The severity of this worm is classified as "medium" and there have been several variants all of which have been attacking random IP addresses, exploiting system vulnerabilities and downloading copies of the worm via FTP.

Second place was given to Netsky.P. This worm, detected in 1.22 percent of positive cases first appeared in 2004 and spreads via e-mail and P2P file-sharing applications.

In third place this year is Exploit/Metafile. Responsible for just over 1 percent of infections, this malicious code is designed to exploit a critical vulnerability in the GDI32.DLL library in Windows 2003/XP/2000. If a computer is vulnerable, Metafile allows the code to be executed, which can then be used, for example, to download and run spyware.

Tearec.A. is in fourth place. This worm, which spreads via e-mail and computer networks, can disable and terminate certain antivirus programs.

Fifth place is occupied by the Q.host.gen Trojan, which was found to be the culprit in 0.76 percent of infected computers.

The remaining places in the ranking are occupied by Torpig.A, a Trojan that steals passwords saved by certain Windows services, Sober.AH.worm!CME- 681, a worm that terminates several processes, including some belonging to security tools; Parite.B, a virus that infects PE files with EXE or SCR extensions; Gaobot.gen, a generic detection for the Gaobot family of worms which exploits software vulnerabilities, and Bagle.pwdzip, a detection of the notorious Bagle family.

The report gives us insight into what kind of threats can be expected in 2007. There will be a continuous threat of financial fraud, considering that the worms responsible for these frauds are high up in the list. Also, hackers are now tending to launch different variants of the same type of malware in a very short period of time in order to increase the probability of computers being infected.