Malware-flingers are taking advantage of vulnerable WordPress sites as part of an attack ultimately designed to spread an information-stealing botnet agent.
Cybercrooks begin the attack by planting malicious scripts on vulnerable sites. Prospective marks are then lured to compromised sites via spammed messages that purport to come from known legitimate sources including Better Business Bureau and LinkedIn, among others. The crooks use social engineering tactics to entice unsuspecting users to click the link found in the email.
Clicking on links in these spam messages points surfers towards compromised WordPress sites – and not the legitimate sites users might have expected to visit. Redirection scripts on compromised sites expose surfers to a variety of drive-by download attacks that attempt to take advantage of well-known (and already patched) Adobe Reader and Windows flaws to drop malware onto poorly secured Windows PCs.
The attack, which uses the infamous Blackhole Exploit kit, is geared towards spreading the Cridex Trojan, an information-stealing strain of malware. Cridex established a botnet using compromised Windows boxen, as explained in a write-up by Trend Micro.
"This malware intercepts browser requests and changes the displayed content according to the configuration, written by the administrator of the botnet," Trend explains. "This way, cybercriminals can trick users into entering valuable information without raising suspicion. It was also found to generate several random domains using domain generating algorithms (DGA)."
A full write-up of the attack, complete with screenshots of spam samples that have featured in the attack, can be found in a blog post by Trend Micro here.
More on the Cridex Trojan can be found in an earlier blog post by M86 Security here.
Earlier this month, Websense warned that vulnerable WordPress content management systems are being abused to promote fake anti-virus (AKA scareware) scams.
"The majority of targets are websites hosted by the WordPress content management system, it said. "At the time of writing, more than 200,000 web pages have been compromised, amounting to close to 30,000 unique websites (hosts). The injection hijacks visitors to the compromised sites and redirects them to rogue AV sites that attempt to trick them into downloading and installing a Trojan onto their computer." ®