Trojan proxy-servers – and multipurpose Trojan viruses that function as proxy servers – can attack and infect multiple computers, in order to establish a ‘zombie network’. The cybercriminal then has control over every computer within the zombie network and can use their combined computing power for the mass distribution of spam email.
Why spammers use zombie networks
By using a Trojan virus to set up a zombie network of thousands – or tens of thousands of infected computers – spammers can benefit in the following ways:
Distribution of the spam is anonymous – message headings and other message delivery information do not reveal the real address of the spammer.
A mass spam email campaign can be completed very rapidly – because large numbers of zombie computers are simultaneously sending the spam emails.
Blacklist technologies – that can prevent the receipt of emails from blacklisted addresses – are often ineffective against this type of spam campaign. This is because there are so many spam mailing computers within the zombie network – and many of the computers may not previously have been used for spam purposes.
How to prevent your computer being used for spam email campaigns
Effective anti-malware software can defend your devices against the Trojan viruses that infect and add machines to a zombie network. Kaspersky Lab offers world-class anti-malware solutions that defend the following devices against computer viruses, Trojan viruses, worms, and a wide range of other cyber threats: