A new campaign to lure users into downloading malware is running on the Waledac botnet, according to security researchers.
This time the botnet is spreading spam messages using a social-engineering ploy promising software that supposedly will enable a victim to read other people’s text messages. In a warning posted on its web site, email security company MX Logic said that one spam email offers a “free 30-day trial” and reads: “Do you want to test your partner or just to read somebody’s SMS? This program is exactly what you need then.” The email contains a link to a web site where users unwittingly download malicious software if they execute a file linked by a “Download Free Trial” notice.
Other emails have questions such as:
“Do you want to catch a cheating girlfriend?”
“Do you want to get your partner off-guard?”
“Do you want to know if your partner is unfaithful?”
All the messages say that when installed on a partner’s mobile phone, the software enables the victim to read every SMS message the partner receives.
In addition, the worm seems to be adopting new methods and tactics.
In a post on his blog, Mikko H. Hypponen, chief research officer at security firm F-Secure said, “If you check the DNS records for these [serving] domains, you’ll notice that they have a time-to-live set to zero. And they use that to change their IP address every time you query it. This is fast fluxing, in effect.”
The botnet spreading the malware is typically working sub rosa on thousands of machines, judging from the number of IP addresses being monitored.
“And all those IP addresses are infected home computers,” wrote Hypponen, “where the owner of the computer has no idea he’s actually running a webserver — which is serving viruses.”
The botnet is not just used to serve malware, the malware itself uses it when calling home, according to Hypponen.
“When Waledac is executed, it does dozens of HTTP posts to IP addresses belonging to this botnet,” he wrote.
The root problem with Waledac’s long-lived domains is they use a Chinese domain name registrar that refuses to cooperate on shutdowns, according to reports.