Crypto Experts Called On To Crack Cyberspy Tool's Encryption

Researchers at Kaspersky Lab crowdsource cracking of heavily fortified Gauss payload in hopes of learning more about the mysterious malware

Investigation into the newly discovered Gauss cyber-surveillance family of malware has hit a brick wall -- specifically, a heavily encrypted payload that has prompted the researchers who discovered the code to share details about the payload in hopes that someone can help them crack it.

Kaspersky Lab researchers today posted online the information they have gathered on Gauss' heavily armored containers, data, and algorithm in order to elicit assistance in cracking the encrypted payload after finding they were unable to do so on their own. Gauss uses a 128-bit RC4 key, which proved to be immune to Kaspersky's brute-force hacking efforts. The goal is to find out what specifically the attackers are after, and researchers want a peek inside the payload for clues.

"It takes a lot of time to brute-force it. We need a more intelligent way to cut down on the time we need to spend on the calculations," says Roel Schouwenberg, senior researcher for global research and analysis at Kaspersky Lab, who described Gauss' encryption approach as "very, very smart."

But even if some crypto rock star is able to crack Gauss' payload, it's unlikely the information hidden inside will reveal which specific applications or systems the sophisticated attack is targeting. "The payload will be revealed. But it won't directly tell us anything about the specific system configuration [that] is required for the payload to become active," Schouwenberg says. "We may never find out what exact system configuration they are after. The attackers are making sure that even if the key is going to be cracked, the specific configuration they are looking for, we are likely never to find out, unless there's a confirmed case in the wild when this thing became active."

The encrypted payload lies in Gauss' USB data-stealing modules, and is built to target systems running a specific program, which has yet to be unmasked by researchers. When the rigged USB stick is plugged into the machine, the malware executes and attempts to decrypt the payload. The malware unlocks the payload if it detects the targeted configurations on a system, according to Kaspersky Lab.

"The use of cryptography and the precautions the authors have used to hide this payload indicate its targets are high-profile. The size of the payload is also a concern. It's big enough to contain coding that could be used for cybersabotage, similar to Stuxnet's SCADA code," says Aleks Gostev, chief security expert, global research and analysis team at Kaspersky Lab. "Decrypting the payload will provide a better understanding of its overall objective and the nature of this threat."

The masterminds behind Gauss appear to be nation/state sponsored, akin to Stuxnet, Duqu, and Flame. Kaspersky Lab and other researchers believe Gauss is related to Flame because it's based on the Flame platform. The big difference is that Gauss appears to have been more about surveillance of Lebanese banks, including the Bank of Beirut, EBLF, BlomBank, ByblosBank, FransaBank, and Credit Libanais -- and even users of Citibank and PayPal. Flame, meanwhile, went after Iranian targets.

Chris Wysopal, CTO for Veracode, says the mere fact that there's an encrypted payload with Gauss is telling: "What's interesting is that there's this encrypted payload at all, because it's clear that someone is trying to hide something," Wysopal says. "And I think one of the reasons it might be there is that it's the weaponized part of it."

He says the creators behind the code appear to be ensuring that it doesn't "run amok." "The fact that it's there [indicates that] there really is something dangerous there, and the writers are trying to keep it from spreading out of control," he says.

Kaspersky found more than 2,500 infections since May, and Gauss appears to be stealing banking credentials from these financial institutions, as well as browsing history and other credentials. The Trojan collects specifics about its victim Windows machines, such as network interface, drive, and BIOS information.

But its ability to spread via USB sticks is eerily reminiscent of Stuxnet, making it appear part of an overall nation-state cyberespionage and cyberweapon arsenal that includes Duqu and Flame as well. Kaspersky Lab earlier this year concluded that Flame has direct ties to Stuxnet, the targeted attack reportedly launched by the U.S. and Israel against an Iranian nuclear facility.

[ Researchers say Flame predates Stuxnet and shares some source code with the first-generation version of Stuxnet. See 'Conclusive' Link Found Between Stuxnet And Flame. ]

Boldizsar Bencsath. with the Laboratory of Cryptography and Systems Security in Budapest, concurs that Gauss resembles Flame both technically and operationally, despite their different targets. "There are clear differences, not just targeting the banking sector and Lebanon, but also on the technical field. The code sometimes is a bit more straightforward, uses libraries for most of the thing, not hiding too much from the development," Bencsath says. "The idea to have a target-tailored encrypted payload is novel. I mean, we expected that as a possible next step, and it surely makes it much more problematic to get a clear view and to get information on every part of the system."

What will it take to crack the payload? Bencsath says that depends on getting more intelligence from targeted victims. "I don't expect it to be cracked without more information from victims, and, of course, we won't be sure that the payload is equal [among] different victims," he says.

Schouwenberg says unlike Stuxnet, where PLC attack code was out there and open for attackers to copy and paste, the missing link with Gauss so far is intelligence on the actual target or targeted systems. "Targeting air-gapped control systems does come to mind," he says. But it won't be like Stuxnet, where anyone could "cut and paste" the available code. "Even if we manage to break the code, the chances of the decrypted code getting on the Net is extremely low. Only a very few [will] have access to this decrypted code," he says. "There's no copy of Gauss."

Gauss was launched last fall, according to Kaspersky Lab. "It's definitely very new," Schouwenberg says, and Kaspersky Lab researchers found it while analyzing Flame samples.

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About the Author(s)

Kelly Jackson Higgins, Editor-in-Chief, Dark Reading

Kelly Jackson Higgins is the Editor-in-Chief of Dark Reading. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise Magazine, Virginia Business magazine, and other major media properties. Jackson Higgins was recently selected as one of the Top 10 Cybersecurity Journalists in the US, and named as one of Folio's 2019 Top Women in Media. She began her career as a sports writer in the Washington, DC metropolitan area, and earned her BA at William & Mary. Follow her on Twitter @kjhiggins.

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