Researchers Warn of Nasty Trojan

By Matthew Hines  |  Posted 2009-04-29 Print this article Print

Just as we're finally being allowed to stop saying the C word (no, don't make me say it!) experts are warning of a powerful new Trojan attack that could make some waves of its own, based on its ability to spread like a traditional virus and embed itself deeply into end users' machines.

In a blog post authored by longtime security guru Paul Henry, of Lumension, the expert contends that the emerging attack, identified as a variant of the Virut.CF Trojan by Symantec and labeled as Scribble-A by Sophos, could cause serious problems based on its mix of proliferation and infection techniques... just as, yep, Conficker has recently done.

"The remote access capability of a Trojan that spreads like a Virus - W32.Virut.CF or W32/Scribble-A is poised to wreak havoc on networks over the coming days.

Embedding itself deep within infected machines, the Trojan will make it difficult to clean up," Henry writes. "It is also reportedly breaking some critical business applications as it attaches itself to them."

Henry said that the sample he is currently studying contains a keylogger that has not yet transmitted any data to a remote host.

The expert said that there have also been "multiple reports of wide spread impact within the enterprise."

A typical starting point for the attack is via Web-borne malware delivery. Then, once it enters an organization's network, it uses open shares to continue to move out, said Henry. The attack also reaches out to multiple Web sites to download additional content, putting a strain on network performance while it spreads itself.

Like Conficker, earlier versions of Virut.CF also used USB thumb drives as an alternative technique for propagation and targets Windows machines that have not been updated with the MS08-067 patch.

"The current variation is polymorphic and uses a packer as well as multiple levels of encryption to evade detection by AV products," Henry said. "It's known to dig in deep by modifying the victim host file to block access to security related Web sites."

The expert said that the virus specifically alters .exe and .scr files, as well as .htm, .html, .php, and .asp with an infected iFrame. The attack also opens a backdoor across IRC using multiple addresses.

Virut and Conficker, which have clearly troubled many organizations, despite attacking patched vulnerabilities, appear to represent a new breed of fast moving, botnet-like threats that employ truly innovative methods for finding their way onto available machines, and staying there.

While many of the attacks being seen in large volumes these days are clearly the output of popular malware authoring toolkits, these newer threats appear to indicate that despite the commoditization of some Trojans, cutting edge iterations of the campaigns still represent truly innovative craftsmanship.

No matter how good we get at stopping this stuff, let's face it - pursuing cyber-attacks is a game of high stakes cat-and-mouse that isn't likely to slow down anytime soon.

So, if you're really sick of talking about Conficker, don't worry. Inevitably something bigger and badder always comes along.

Matt Hines has been following the IT industry for over a decade as a reporter and blogger, and has been specifically focused on the security space since 2003, including a previous stint writing for eWeek and contributing to the Security Watch blog. Hines is currently employed as marketing communications manager at Core Security Technologies, a Boston-based maker of security testing software. The views expressed herein do not necessarily represent the views of Core Security, and neither the company, nor its products and services will be actively discussed in the blog. Please send news, research or tips to |

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