Tag Archives: Trojan-Downloader-Karagany

Shipping Confirmations Back on the Radar

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By Andrew Brandt

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After a prolonged absence, waves of Trojans distributed as Zipped email attachments have been showing up in our spam traps for a few weeks. The spam messages employ the same hackneyed shipping confirmation pretext as many previous iterations of this scam. This technique’s emergence as a common malware distribution method correlates with the emergence of Trojan-Downloader-Tacticlol.

The messages claim to come from various express shippers, including DHL, UPS, and FedEx, as well as one that may have originated in a malware guy’s imagination: Post Express. And even though the distribution method mimics those used by Tacticlol, the payloads haven’t been limited to that Trojan. This time around, the files belong to a wider variety of malware, including not only several new variants of Tacticlol but also Trojan-Downloader-Karagany, Trojan-Relayer-Highport, and SpyEye.

The Trojans’ icons look like Office documents or Acrobat PDFs, which serve to further convince victims that the file isn’t dangerous. The email attachments — Zip files with names such as tracking.zip, Post_Express_Label.zip or DHL_tracking.zip — aren’t dangerous unless you open the attachment, extract the Trojan, and execute it. But once you do, you’re in for a world of trouble.

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New Year’s Drive-By Brings a Recursive Rogue

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By Andrew Brandt

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On the morning of January 2nd, still bleary eyed, I checked my email to find a charming notification informing me that I’d received an electronic greeting card. Yay! I thought to myself: The first targeted malware of 2011 plopped right into my lap.

I immediately pulled up my research machine, browsed to the URL in the message (don’t try this at home, kids), and found my test system swamped in malware. After classifying the files and their source URLs into our definitions — I didn’t want this to happen to you, after all — I turned the computer back off and slept until Tuesday, when I resumed my analysis.

As it turns out, the payloads delivered by the drive-by download are as common as sand at the beach, but some of the techniques used by the malware’s distributor to obfuscate the true nature of the executable payload files (which may have been stored on what appears to be a hijacked, legitimate server running Joomla) are fairly novel, and also a bit ridiculous.

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Karagany Isn’t a Doctor, but Plays One on Your PC

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By Andrew Brandt

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A Trojan that pulls a sly performance of now-you-see-me-now-you-don’t disguises itself on an infected system as the Adobe Updater, a real program that’s installed alongside such mainstay applications as the Adobe Reader. This method of hiding in plain sight means the downloader, Trojan-Downloader-Karagany, may remain active on an infected system for an extended period of time, reinfecting PCs even after the more obvious payloads have been cleared up.

During the initial infection, subtlety is this Karagany’s strong suit. When executed, it pulls an act I find slightly more interesting than the conventional file copies itself from one place to another, then deletes the original behavior that is so common among contemporary malware.

In this case, the malware app (which uses an Adobe icon) does copy itself to another location — the \Application Data\Adobe folder under the currently logged-in user’s account, using the filename AdobeUpdater.exe — but leaves behind a benign program afterward, in exactly the same place as the original, and with the same filename as the original. Watch this video to see just how slick this shell game can be.

The Trojan makes a duplicate of a legitimate Windows app (the Microsoft HTML Application Host, or MSHTA.exe), naming the copy with the same filename the Trojan used at the time it was executed, and replaces itself with the renamed MSHTA.exe in precisely the same location. The effect is low-key — the program simply seems to lose its icon.

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