Citadel Trojan Moves from Crime to Espionage

The group behind the malicious software pulled it from public distribution last year. Now the group is using it to hunt for secrets inside companies and government.

A team of attackers with a penchant for Shakespearian verse has used the popular cyber-crime program known as Citadel to infiltrate government offices in Poland and Japan as well as a number of companies in Denmark and Sweden, according to a report published by security firm McAfee.

The string of espionage campaigns marks a significant departure for the group of developers behind the Citadel Trojan. It's a program well-known for the ability to compromise consumers' computers and quickly steal money from the accounts of targeted banks. Last year, however, the developers behind the Trojan ceased openly selling the tool and now appear to be using it for nonfinancial crimes, said Ryan Sherstobitoff, a threat researcher with McAfee Labs.

Since October 2012, the team of attackers—dubbed the Poetry Group for its inclusion of Shakespearian verses in its code—has targeted government offices in Poland and a variety of industries in Denmark, Sweden and other countries, including health care, education and manufacturing. In its most recent campaign starting in mid-January, the group added government offices in Japan to its list of targets.

"It looks like a for-hire data gathering operation," Sherstobitoff said. "Basically, a group of individuals that has been hired by some other third party to go and gather data from specific targets."

In the half-dozen campaigns conducted since October, the Poetry Group has hit 27 Japanese government offices, 43 Polish government offices and a variety of corporate victims in Denmark, Sweden, Spain, the Netherlands, Estonia, Czech Republic and Switzerland. The espionage attacks impacted more than 1,000 victims in total, McAfee stated in its report, published Jan. 31.

Each campaign includes a variety of quotations, many from Shakespeare's "Hamlet." Whether the lines are an affectation of the group or have some functional purpose is unclear, Sherstobitoff said. Some of the quotes seem supportive of England, while others are negative of other countries, particularly Denmark.

"Given the political references made in the executable, it is possible that this is hacktivism," he said.

The attacks come after the developers of the Citadel Trojan, which is a variant of the Zeus banking malware, had a major break with the community of cyber-criminals that collaborate on various underground Web forums—or sites.

In July 2012, "Aquabox," the handle of the primary developer behind the Citadel banking Trojan, caused a stir when he announced that the program would no longer be sold to anyone outside of a private group of customers. A number of forum members reportedly criticized him for being corrupted by the success of the program, resulting in the developer being banned from some large cyber-crime forums.

In the end, the group may be operating more silently to avoid law-enforcement attention, Sherstobitoff theorized.