Travnet trojan compresses files to send more info to data thieves

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A new trojan capable of compressing stolen data and uploading document files to remote servers is being used in a targeted operation, researchers have found.

Upon infecting a machine, the malware, dubbed “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.

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

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

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 is first compressed using the Lempel–Ziv–Storer–Szymanski (LZSS) algorithm. Data is then 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 wrote.

In findings released last month, McAfee determined that Travnet was being delivered to victims through emails, and that the trojan exploited already-patched vulnerabilities in Microsoft Office – for example, CVE-2010-3333, a flaw that was exploited by the Red October cyber espionage ring.

Adam Wosotowsky, a messaging data architect at McAfee Labs, told SCMagazine.com on Wednesday that researchers are still monitoring the campaign, but that attackers may be targeting organizations in Russia and Mongolia because of the languages infected files were written in.

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