Posts Tagged: Kolypto


25
Jul 17

How a Citadel Trojan Developer Got Busted

A U.S. District Court judge in Atlanta last week handed a five year prison sentence to Mark Vartanyan, a Russian hacker who helped develop and sell the once infamous and widespread Citadel banking trojan. This fact has been reported by countless media outlets, but far less well known is the fascinating backstory about how Vartanyan got caught.

For several years, Citadel ruled the malware scene for criminals engaged in stealing online banking passwords and emptying bank accounts. U.S. prosecutors say Citadel infected more than 11 million computers worldwide, causing financial losses of at least a half billion dollars.

Like most complex banking trojans, Citadel was marketed and sold in secluded, underground cybercrime markets. Often the most time-consuming and costly aspect of malware sales and development is helping customers with any tech support problems they may have in using the crimeware.

In light of that, one innovation that Citadel brought to the table was to crowdsource some of this support work, easing the burden on the malware’s developers and freeing them up to spend more time improving their creations and adding new features.

Citadel users discuss the merits of including a module to remove other parasites from host PCs.

Citadel users discuss the merits of including a module to remove other parasites from host PCs.

Citadel boasted an online tech support system for customers designed to let them file bug reports, suggest and vote on new features in upcoming malware versions, and track trouble tickets that could be worked on by the malware developers and fellow Citadel users alike. Citadel customers also could use the system to chat and compare notes with fellow users of the malware.

It was this very interactive nature of Citadel’s support infrastructure that FBI agents would ultimately use to locate and identify Vartanyan, who went by the nickname “Kolypto.” The nickname of the core seller of Citadel was “Aquabox,” and the FBI was keen to identify Aquabox and any programmers he’d hired to help develop Citadel.

In June 2012, FBI agents bought several licenses of Citadel from Aquabox, and soon the agents were suggesting tweaks to the malware that they could use to their advantage. Posing as an active user of the malware, FBI agents informed the Citadel developers that they’d discovered a security vulnerability in the Web-based interface that Citadel customers used to keep track of and collect passwords from infected systems (see screenshot below).

A screenshot of the Citadel botnet panel.

A screenshot of the Web-based Citadel botnet control panel.

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