Besides number one position, AutoRun variants occupied eighth and ninth positions as Trojan.Autorun.AET and WORM.AUTORUN.VHG represented a total of 2.08% and 1.09% harmful software respectively.

BitDefender researchers claim that the share of Autorun can be even higher keeping in mind the notorious Conficker worm, which is also circulating through the Window feature, holds the second place with 5.66% of total samples in H1 2010.

The increased occurrence of PDF exploits can be seen in the BitDefender report, with generic Exploit.PDF-JS.Gen signature emerged as the third most triggered exploit this year (4.80%). The malware spread through these PDF attacks also common, with Exploit.PDF-Payload.Gen, holding the seventh place.

Trojan.Clicker.CM scores 3.18% of the overall number of infected systems and holds fourth position. During the first six months of 2010, Clicker.CM was often found on websites hosting unlawful applications like cracks, keygens and serial numbers for famous commercial software applications. The Trojan is chiefly used to force ads as popup windows for increasing advertisement revenues of hackers.

The fifth position was occupied by Win32.Sality.OG with 2.90% of the infections triggered worldwide. This e-threat is a polymorphic file infector that appends its encrypted code to executable files (.exe and .scr binaries). It delivers a rootkit and hit antivirus solutions running on the system in order to conceal itself from the infected system.

Holding sixth place on the BitDefender malware top for H1-2010, Trojan.Wimad.Gen.1 exploits a feature created in ASF and WMV files, which enables, which enable their maker to specify a URL where the appropriate codec can be found if it is not installed on the system.

As per BitDefender, Trojan.FakeAV.KUE concludes the H1 2010 malware list with a percentage of 1.76% of the overall number of infections.