The U.S. government this week put a $10 million bounty on a Russian man who for the past 18 years operated Try2Check, one of the cybercrime underground’s most trusted services for checking the validity of stolen credit card data. U.S. authorities say 43-year-old Denis Kulkov‘s card-checking service made him at least $18 million, which he used to buy a Ferrari, Land Rover, and other luxury items.
Launched in 2005, Try2Check soon was processing more than a million card-checking transactions per month — charging 20 cents per transaction. Cybercriminals turned to services like this after purchasing stolen credit card data from an underground shop, with an eye toward minimizing the number of cards that are inactive by the time they are put to criminal use.
Try2Check was so reliable that it eventually became the official card-checking service for some of the underground’s most bustling crime bazaars, including Vault Market, Unicc, and Joker’s Stash. Customers of these carding shops who chose to use the shop’s built-in (but a-la-carte) card checking service from Try2Check could expect automatic refunds on any cards that were found to be inactive or canceled at the time of purchase.
Many established stolen card shops will allow customers to request refunds on dead cards based on official reports from trusted third-party checking services. But in general, the bigger shops have steered customers toward using their own white-labeled version of the Try2Check service — primarily to help minimize disputes over canceled cards.
On Wednesday, May 3, Try2Check’s websites were replaced with a domain seizure notice from the U.S. Secret Service and U.S. Department of Justice, as prosecutors in the Eastern District of New York unsealed an indictment and search warrant naming Denis Gennadievich Kulkov of Samara, Russia as the proprietor.
At the same time, the U.S. Department of State issued a $10 million reward for information leading to the arrest or conviction of Kulkov. In November 2021, the State Department began offering up to to $10 million for the name or location of any key leaders of REvil, a major Russian ransomware gang.
As noted in the Secret Service’s criminal complaint (PDF), the Try2Check service was first advertised on the closely-guarded Russian cybercrime forum Mazafaka, by someone using the handle “KreenJo.” That handle used the same ICQ instant messenger account number (555724) as a Mazafaka denizen named “Nordex.”
In February 2005, Nordex posted to Mazafaka that he was in the market for hacked bank accounts, and offered 50 percent of the take. He asked interested partners to contact him at the ICQ number 228427661 or at the email address polkas@bk.ru. As the government noted in its search warrant, Nordex exchanged messages with forum users at the time identifying himself as a then-24-year-old “Denis” from Samara, RU.
In 2017, U.S. law enforcement seized the cryptocurrency exchange BTC-e, and the Secret Service said those records show that a Denis Kulkov from Samara supplied the username “Nordexin,” email address nordexin@ya.ru, and an address in Samara.
Investigators had already found Instagram accounts where Kulkov posted pictures of his Ferrari and his family. Authorities were able to identify that Kulkov had an iCloud account tied to the address nordexin@icloud.com, and upon subpoenaing that found passport photos of Kulkov, and well as more photos of his family and pricey cars.
Like many other top cybercriminals based in Russia or in countries with favorable relations to the Kremlin, the proprietor of Try2Check was not particularly difficult to link to a real-life identity. In Kulkov’s case, it no doubt was critical to U.S. investigators that they had access to a wealth of personal information tied to a cryptocurrency exchange Kulkov had used.
However, the link between Kulkov and Try2Check can be made — ironically — based on records that have been plundered by hackers and published online over the years — including Russian email services, Russian government records, and hacked cybercrime forums. Continue reading