BitDefender, a world-wide developer of antivirus software and internet security packages, has announced that malware packers gained more popularity in April.

Malware packers gained great popularity in April, as three of the top positions on BitDefender's list are occupied with malware packed by such software. They are all packed with the same packer - NSAnti - which has already did quite a lot of harm recently.

The fact that repacking malware is a very smart way to avoid antivirus detection is known by hackers and they use it more and more often. This technique saves hackers time and effort, as they do not have to research new viruses from scratch.

There exists another tool that won hackers' favor in April: Loader.N. This tool runs, decrypts and enables two other packed pieces of malware (Trojans Kobcka and Downloader.Agent). Loader.N turns the infected computer into a spam bot. The decryptor is easily detected by BitDefender software, so the hackers who used the malware did not achieve much.

The rest of the top ten is pretty well-populated with mass mailer viruses turning machines into spam bots.

The list includes:

1. Packer - Malware. NSAnti.AD - 33,71%
2. Win32 - Netsky. P@mm - 7,48%
3. Win32 - Worm. Sohanad.NAW - 4,56%
4. Packer - Malware. NSAnti.AG - 2,86%
5. Trojan - Loader.N - 2,25%
6. Trojan - Dropper. Cutwail.F - 2,04%
7. Win32 - Netsky. AA@mm - 1,98%
8. Win32 - NetSky. D@mm - 1,98%
9. Packer - Malware. NSAnti.Z - 1,87%
10. Win32 - Nyxem. E@mm - 1,65%
11. Others - 39,62%