ONE OF THE TOP three malware programs affecting businesses in the second quarter is a worm that takes advantage of the large number of companies still using Windows XP, Trend Micro has warned.
The worm, dubbed DOWNAD, also known as Conficker, can infect an entire network via a malicious URL, spam email, or removable drive. Windows XP is particularly susceptible to this threat because it is known to exploit the MS08-067 Server service vulnerability in order to execute arbitrary code.
DOWNAD also has its own domain generation algorithm (DGA) that allows it to create randomly-generated URLs. It then connects to these created URLs to download files to the system. Trend Micro said that around 175 IP addresses are found to be related to the DOWNAD worm and that these IP addresses use various ports and are randomly generated via the DGA capability of DOWNAD.
"During our monitoring of the spam landscape, we observed that in Q2, more than 40 percent of malware related spam mails are delivered by machines infected by DOWNAD worm," said Trend Micro anti-spam research engineer Maria Manly in a blog post.
"A number of machines are still infected by this threat and leveraged to send the spammed messages to further increase the number of infected systems. And with Microsoft ending the support for Windows XP this year, we can expect that systems with this OS can be infected by threats like DOWNAD."
The security company warned that spam campaigns delivering FAREIT, MYTOB, and LOVGATE payloads in email attachments are attributed to DOWNAD infected machines. FAREIT is a malware family of information stealers that download variants of the Zeus Trojan, while MYTOB is an old family of worms known for sending a copy of itself in spam attachments.
The other top sources of spam with malware are the CUTWAIL botnet, together with Gameover ZeuS (GoZ). Manly said CUTWAIL was actually previously used to download GoZ malware but now a malware called UPATRE employs GoZ malware or variants of ZBOT which have peer-to-peer functionality.
"In the last few weeks we have reported various spam runs that abused Dropbox links to host malware like UPATRE," Manly said. "We also spotted a spammed message in the guise of voice mail that contains a Cryptolocker variant. The latest we have seen is a spam campaign with links that leveraged CUBBY, a file storage service, this time carrying a banking malware detected as TSPY_BANKER.WSTA."
According to Manly, cybercriminals and threat actors are probably abusing file storage platforms to mask their malicious activities and go undetected in the system and network.
"As spam with malware attachment continues to proliferate, so is spam with links carrying malicious files. The continuous abuse of file hosting services to spread malware appears to have become a favoured infection vector of cyber criminals most likely because this makes it more effective given that the URLs are legitimate thereby increasing the chance of bypassing anti-spam filters," she added. µ