Trojan Variant Packages with Rootkit

Friday, April 26, 2013 @ 10:04 AM gHale

A new variant of the Gozi banking Trojan hit thousands of machines in the United States and is targeting the master boot record (MBR) of Internet Explorer users.

A rootkit, a feature not often found in financial malware, ended up packaged with the latest version of Gozi, said researchers at security firm Trusteer.

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The rootkit is particularly difficult to extract, said Etay Maor, a Trusteer researcher in a blog post.

“Due to their strategic placement in the operating system’s kernel, rootkits are difficult to identify and remove,” Maor said.

Gozi, packaged with the rootkit, sits silently in the MBR, waiting for Internet Explorer (IE) to launch, he said. Once the browser is running, the Trojan injects itself into victims’ browsers so it can steal financial information that users enter into sites.

Yishay Yovel, vice president of marketing for Trusteer, said the firm detected as many as a couple thousand infections of this variant in the United States.

Despite key leaders in the cyber gang responsible for the malware facing charges by federal authorities, the campaign has continued to persist, Yovel said.

In 2010, Nikita Kuzmin, who federal officials feel is the creator of Gozi, ended up arrested in the United States, followed by Deniss Calovskis, who police said wrote parts of the Trojan’s code. Police busted Calovskis’ in November in Latvia.

Since Gozi first appeared in 2005, federal prosecutors estimate it has infected at least 100,000 computers worldwide, including 25,000 in the United States, causing tens of millions of dollars in losses.

“There was an expectation that Gozi would decline with the arrests, but now we are seeing this evolution,” Yovel said.

Attackers’ means of distributing the malware has remained the same, Yovel said, with perpetrators using drive-by download or phishing emails to lure users into installing weaponized documents containing the Trojan.

To remediate after a Gozi infection, Trusteer reseachers said users should do a complete hard drive format, reinstall their operating system and implement enterprise security solutions, prior to updating their online banking credentials.

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