Security researchers discover 'indestructible' botnet.
Cracking the TDL-4 botnet is going to be hard, say security experts.
The botnet, known as TDL, targets Windows PCs and is difficult to detect and shut down.
Code that hijacks a PC hides in places security software rarely looks and the botnet is controlled using custom-made encryption.
Security researchers said recent botnet shutdowns had made TDL's controllers harden it against investigation.
The 4.5 million PCs have become victims over the last three months following the appearance of the fourth version of the TDL virus.
The changes introduced in TDL-4 made it the "most sophisticated threat today," wrote Kaspersky Labs security researchers Sergey Golovanov and Igor Soumenkov in a detailed analysis of the virus.
"The owners of TDL are essentially trying to create an 'indestructible' botnet that is protected against attacks, competitors, and anti-virus companies," wrote the researchers.
Recent successes by security companies and law enforcement against botnets have led to spam levels dropping to about 75% of all e-mail sent, shows analysis by Symantec.
A botnet is a network of home computers that have been infected by a virus that allows a hi-tech criminal to use them remotely. Often botnet controllers steal data from victims' PCs or use the machines to send out spam or carry out other attacks.
The TDL virus spreads via booby-trapped websites and infects a machine by exploiting unpatched vulnerabilities. The virus has been found lurking on sites offering porn and pirated movies as well as those that let people store video and image files.
Cracking the TDL-4 botnet is going to be hard, say security experts.
The botnet, known as TDL, targets Windows PCs and is difficult to detect and shut down.
Code that hijacks a PC hides in places security software rarely looks and the botnet is controlled using custom-made encryption.
Security researchers said recent botnet shutdowns had made TDL's controllers harden it against investigation.
The 4.5 million PCs have become victims over the last three months following the appearance of the fourth version of the TDL virus.
The changes introduced in TDL-4 made it the "most sophisticated threat today," wrote Kaspersky Labs security researchers Sergey Golovanov and Igor Soumenkov in a detailed analysis of the virus.
"The owners of TDL are essentially trying to create an 'indestructible' botnet that is protected against attacks, competitors, and anti-virus companies," wrote the researchers.
Recent successes by security companies and law enforcement against botnets have led to spam levels dropping to about 75% of all e-mail sent, shows analysis by Symantec.
A botnet is a network of home computers that have been infected by a virus that allows a hi-tech criminal to use them remotely. Often botnet controllers steal data from victims' PCs or use the machines to send out spam or carry out other attacks.
The TDL virus spreads via booby-trapped websites and infects a machine by exploiting unpatched vulnerabilities. The virus has been found lurking on sites offering porn and pirated movies as well as those that let people store video and image files.