A series of files are being circulated across the Internet at peer to peer networks that allegedly contain music and videos, but also include adware -- an IST Toolbar -- in order to download videos and music, said PandaLabs, the research and development arm of Panda Software USA, a software-security company.

The adware program often is used as an entry-point for various cyber threats from viruses to Trojan Horses that can cause damage to their computer systems. "In the past six months we've seen a trend in multi-stage attacks against machines," Patrick Hinojosa, chief technology officer at Panda Software USA, said Wednesday. "There are several reasons for this. Either those launching the attacks haven't determined what they want to use the machines for or they want to install a general purpose program so they can take control of the machine."

Many times this is a precursor to creating a bot network, Hinojosa said. Panda has developed security signatures to detect this program that is automatically distributed to its customers through the Internet.

Those downloading the files are required to also download a license to play the files, which involves agreeing to install adware. The files, alleged video file (*.wmv) or de audio file (*.wma), received by PandaLabs do not contain video or music. The files are detected by Panda Software as WmaDownloader.B.

Hinojosa said many of these sites being affected contain "illicit" copyrighted media content. "I don't think it's going across America Online at the moment, but mainly the backdoor P2P illegal file sharing networks," he said.

When the files launch on the computer, a window is displayed that prompts the user to acquire a license. The message explains to get the free license they must install an IST Toolbar. When this message is displayed, the user is also asked to install an ActiveX Control, which is the IST Toolbar mentioned in this window. Users that don't agree to install the program will not be affected, but neither will they have the ability to play the video or audio file.

If users agree to install it, the IST Toolbar will be downloaded, infecting the system and allowing the file to be played, if it exists. A window notifying users that they must acquire a license will also appear.