August 21, 2007

A particularly nasty bit of malware - Storm Worm

Be very careful when opening emails especially if it requires you to install an applet to ensure 'security'. From The Register:
Storm Worm of a thousand faces
Authors of a particularly nasty piece of malware known as Storm Worm have yet again shifted their tactics. They are creating a flood of email hoaxes that try to install a bogus "applet" so victims can redeem membership benefits to clubs related to music, online dating and other interests.

The new emails bear subject headings such as "User info," "Membership support" and "Login information," and contain purported login credentials for sites that offer the gamut of services tailored to online music aficionados, cat lovers and poker players, according to this post by F-Secure.

Just as genetic mutations allow a particular type of caterpillar or breed of dog to better withstand virulent disease, the frequent changes in Storm improve its resiliency against attacks from rival criminal gangs and security providers. The tactical shifts are crucial since the success of Storm relies on the ability to dupe recipients into clicking on links and installing programs.

The most recent strain of Storm lures victims to sites that claim an "applet" needs to be installed so the user can login securely, according to this post by Johannes Ullrich, CTO for SANS Internet Storm Center.

The resulting applet.exe - which installs a backdoor on the user's machine - represents a case study in the benefits of adaptation. The binary morphs about every 30 minutes, making it particularly hard for antivirus programs to identify it as malware. Indeed, earlier on Tuesday, only 14 of 32 anti-virus programs detected a version of the applet Ullrich had downloaded. Later in the day, many of those laggards added definitions to flag the applet, but its ability to change so frequently means it may still be hard to detect.

"A lot of commonly used antivirus tools don't detect" Storm, Ulrich told The Reg. "The traditional signature approach that some of the antivirus vendors use really isn't all that useful anymore."

Programs that have the best chance of identifying the malware are those that use heuristics, or algorithmic rules of thumb, for identifying software that has a high likelihood of containing malware.

Like other Storm-related malware, applet.exe excels at cloaking itself from security researchers. The program actively monitors its host machine for VMware and will refuse to execute correctly if the virtualization software is detected. It also wraps itself in a packing container that makes it difficult to prevent outsiders from peering into the inner workings of the binary.
Very nasty stuff... The malware allows your system to be used for sending out other viruses and spam emails -- these applications run undetected in the background and are a royal pain to remove -- generally requiring a re-format of the hard disk and a re-installation of all software and data files. The best bet? * If you don't recognize the sender, don't open it. * Turn off the preview pane in Outlook * If you do recognize the sender and you were not expecting the email, call them first to see that it was legitimate -- their system might be infected and the malware trying to infect your system... Posted by DaveH at August 21, 2007 9:48 PM
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