Trojan can Compress Files

Tuesday, April 30, 2013 @ 04:04 PM gHale


A new Trojan capable of compressing stolen data and uploading document files to remote servers is now seeing use in targeted operations, researchers said.

Upon infecting a machine, the malware, called “Travnet,” gathers victims’ information – such as their computer name, IP address, IP configuration details and a list of running processes – to communicate the information to a command-and-control server.

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From there, botnet operators can determine the value of information on the compromised machines at their disposal, while sending further instructions, McAfee Labs researchers said.

Travnet can steal files, such as Microsoft Office documents, PDFs and various text files, said Umesh Wanve, a principal research engineer at McAfee Labs in a blog post.

The Trojan then uses data compression and data-encoding methods, which allows it to send large amounts of information to botnet operators. The hijacked data first compresses using the Lempel–Ziv–Storer–Szymanski (LZSS) algorithm. Data then ends up encoded using custom Base64, a technique that converts binary data to the ASCII (American Standard Code for Information Interchange) text format.

“The compressed file can be too big to send over HTTP [hypertext transfer protocol], so the bot sends the compressed file in chunks of 1,024 bytes,” Wanve said.

In findings released last month, McAfee determined Travnet was going to victims through emails, and the Trojan exploited already-patched vulnerabilities in Microsoft Office, like CVE-2010-3333, a flaw exploited by the Red October cyber espionage ring.



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