Lirva starts to spread faster as two new variants emerge

Panda Software’s tech support services have continued to receive reports of incidents caused by the new worm Lirva (W32/Lirva). Over the last 24 hours, it has been spreading steadily and is now ranked as the third most frequently detected virus by Panda ActiveScan. Lirva now accounts for just over 6 percent of all infections detected and removed by Panda’s free, online virus scanner. It is most active in Europe and the US, although it has also been detected in various other countries around the world.

Due to the increasing threat posed by Lirva, Panda Software has made the PQREMOVE utility available to all users. This application is designed to repair the possible damage that the virus could inflict on computers and can be downloaded from

Panda Software’s Virus Laboratory has also detected two new variants -B and C- of Lirva. These are very similar to the original worm, although there are certain differences such as the size of the infected file. The company’s tech support services have already started to receive reports of the first incidents caused by Lirva.C

This new malicious code and its variants are designed to spread rapidly using various means of transmission, including e-mail, the file swapping tool KaZaA and the IRC and ICQ chat programs. When via e-mail, they exploit a known vulnerability in Microsoft Internet Explorer to run automatically when the message carrying the malicious code is viewed in the Preview Pane.

These worms are also programmed to block antivirus programs and firewalls in order to render the victim’s computer defenseless.

Panda Software advises clients to treat all e-mails and files received with caution and, if they haven’t already done so, to update their antivirus solutions from From this address, users can also access the company’s free, online scanner Panda ActiveScan to disinfect computers that may have been hit by these malicious code.

More detailed information about Lirva, Lirva B and Lirva C is available in Panda Software’s Virus Encyclopedia.

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