Citadel Trojan Gets More Customer-Friendly

The underground developers of the Citadel Trojan have released a new version of the malware kit with a more user-friendly interface for novice cybercriminals and that automates the creation of Web injections.

Researchers at RSA, the security division of EMC, say the so-called Citadel v1.3.5.1 "Rain Edition" new version of the Trojan crimeware kit makes the sixth release of the Zeus-based software, which first came out in January. It now costs 41 percent more than it did then, too, they say: A basic Citadel version sells for $3,391.

Citadel now also offers a new feature called "dynamic config," which lets botmasters create Web injection attacks and send them to selected bots. "Today’s fraud happens in real time, so speed is of the essence. This nifty function allows Trojan operators to create web injections and use them on the fly, pushing them to selected bots without the hassle of pushing/downloading an entire new configuration file," said Limor Kessem, a top cyberintelligence expert at RSA, in a blog post today.

It works like this: Citadel-infected bots call home to the command-and-control server every two minutes to get updated injection "packs."

"The whole system will be managed by a clever distribution mechanism dictating which injection(s) go to which bot or group of bots," Kessem said. "This will not cancel out the configuration file or the injections it already contains. Botmasters can choose whether to use both simultaneously, or work with one of the sources at a time. If an injection in the usual config already has a more recent version, the newest will be automatically used."

Meantime, the Citadel creators also are offering more customer support with this version. It allows up to five programmers per admin on the tool, which allows the bad guys to hire out help to infect machines. "The injection sellers could create and save their work, get paid by the piece, and work with multiple botmasters – FaaS [Fraud as a service] at its best!"

The user interface was enhanced for less technical attackers, and it appears the gang behind Citadel is trying to downsize its tech support operations. "One of Citadel’s strongest points in the cybercrime market has apparently become increasingly charging (more customers, more troubleshooting). Citadel tells customers that 'Complex customer support requests of a highly technical nature will no longer be accommodated due to the elevated number of such requests.' Users can find help in sharing their issues with peers on the Citadel CRM or discussion forum," RSA's Kessem said.

It's still sold only in Russian-speaking forums, according to RSA, and to prevent law enforcement or researchers from getting the software, the creators say they reserve the right to not sell to any buyer.

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