A wave of cyberattacks early this year that resulted in the theft of hundreds of millions of dollars from banks mostly in Eastern Europe began with villagers in nearby regions being recruited to open their first bank accounts and receive debit cards.
Dozens of these so-called "mules" set up their accounts with phony documents provided by an organized crime gang that paid them off and later used other "mules" to cash out those accounts in ATM machines in various cities in the region, hitting five banks in Eastern Europe and one in Africa and stealing anywhere from $3 million to $10 million from each.
The well-orchestrated bank heist campaign appears to be the handiwork of an Eastern European crime gang that blended the physical fraud actions of money mules and phony documentation with a cyberattack that began with spear-phishing emails. Those emails got the criminals access into low-level bank employee user accounts, and then ultimately, to bank employees with domain administrator accounts, says Brian Hussey, Trustwave's vice president of cyberthreat protection and response. Trustwave helped investigate the attacks after a payment-card processor in February of this year spotted a series of sketchy ATM withdrawals from the banks' customer accounts.
Trustwave says the attack campaign "represents a clear and imminent threat to financial institutions in European, North American, Asian and Australian regions within the next year."
Although the attack campaign was limited to nations in Eastern Europe and Africa, it could be deployed against banks in other geographic areas as well, Hussey says.
"This is a bit of warning to banks in western countries, as well as Eastern Europe and Russia," Hussey says. "It's really interesting how they combined the physical element with the cyber element, in a very organized fashion."
Trustwave's incident response team was hired by a third-party payment processor in March whose network had been infiltrated by the attackers as part of the heist. "They [the cybercriminals] took out 4G of data over a month. They had all the domains, administrator credentials ... and access to the payment processor," says Hussey, a former FBI cybercrime investigator.
The heist went down this way, according to Trustwave:
Physical Stage I Recruit of mules to open bank accounts and issue new debit cards
Cyber Stage I Obtain unauthorized privileged access to the bank’s network
Cyber Stage II Compromise third-party processor’s network
Cyber Stage III Obtain privileged access to Card Management System
Cyber Stage IV Activate overdraft on specific bank accounts
Physical Stage II Cash-out from ATMs in multiple cities and countries
The criminals needed access to the bank employee accounts to set overdraft features to the debit-card accounts the mules had opened. That's where a low-risk debit card account can be converted to a credit card so a customer can withdraw cash even if he or she doesn't have the requisite balance. Once they stole those bank credentials, they altered the debit cards to low risk and high-overdraft levels and eliminated existing anti-fraud parameters set for the accounts. With the overdraft feature, "you can take $25,000 to $30,000" out of the ATM per card, Hussey notes.
"In a very coordinated fashion, people in Eastern Europe were at ATMs and taking out as much money as they could from as many ATMs as they could … In video footage, you could see them walking out and handing over the cash," he says.
He says his team hasn't had enough information to publicly say the attacks were aligned with a specific cybercrime gang, although it is possible it could be the infamous Carbanak/aka FIN7 group out of Russia. "But we haven't found any technical clues" to determine that, he says.
Weak Links in the Chain
The attacks took advantage of several configuration and management holes in the banking systems. According to Trustwave, because the core banking systems and card management software weren't integrated, there were no red-flag detections of fraud, which gave the criminals more time and leeway to pull off the heist.
User authorization controls was another weakness: a single bank employee user could both request changes to and approve changes to debit card account, and domain administrator privileges were easily stolen via the Windows Domain administrator, Trustwave said in its report.
Interestingly, malware was not the centerpiece of the campaign. "They were living off the land using tools used by real users, such as network scanning and some administrative tools," Hussey says. "They did as much as they could not using malware" so as not to raise any alarms, he says.
With all of the banks hit, Trustwave's investigators saw the same MO that led them to conclude the campaign originated out of an organized crime operation. And there are likely more victim banks that haven't yet discovered they were breached, Hussey says.
"We think this is just one [instance] of many attacks," he says.
Ilia Kolochenko, CEO of Web security firm High-Tech Bridge, points out that the attacks' techniques are less sophisticated than those that Western banks experience. "This can probably be explained by practicality and a pragmatic approach from attackers – banking infrastructure and enacted security controls in developing countries are much less sophisticated than in the Western World," Kolochenko says. Even so, Western banks should be on alert for this type of campaign, however, he says.
- Cybercrime Gangs Blend Cyber Espionage And Old-School Hacks In Bank Heists
- Carbanak's Back And Using Google Services For Command-and-Control
- Top Russian Banks, Payment Service Providers Targeted By Tinba
- GDPR Compliance: 5 Early Steps to Get Laggards Going
Join Dark Reading LIVE for two days of practical cyber defense discussions. Learn from the industry’s most knowledgeable IT security experts. Check out the INsecurity agenda here.