Security researchers have warned once again that cyber criminals could step up their attack efforts, including the use of the Zeus trojan, this Halloween.
Trend Micro said that Zbot' spam was the number one threat this month, spreading the Zeus botnet, known for online banking attacks and stealing identities.
Rik Ferguson, security researcher for Trend Micro, said that it was at number one as it wasn't just a single botnet, but also a software agent and command and control server.
"It's a serious threat, because the bot gives criminals remote control over your PCs," he said. "They can use this for sending spam, keylogging and stealing your information. They can also use you as a proxy and connect you to other places."
Ferguson said it could bypass firewalls, disable security software and grab transaction authentication numbers, so that it can steal passwords for online banking.
The Zbot is a threat to businesses, too. A recent spear phishing attack on Microsoft Webmail showed that criminals were tailoring spam mails to target company employees.
The recent RSA conference revealed that the trojan could be bought on the black market for $1,000, and was one of the most popular to use. However, Ferguson said that you could now buy it for 200 in a special deal for new fraudsters.
Ferguson warned that cyber criminals would use Halloween to infect PCs with Zeus by tailoring their scams, for example by using Halloween e-cards and social networking sites.
He said: "We urge people to be vigilant when clicking on links leading to unknown websites, no matter how tempting the offer may be."
