How One Criminal Hacker Group Stole Credentials for 800,000 Bank Accounts

A closer peek at a Russian-speaking crime group that has lifted credentials for as many as 800,000 online banking accounts, shows more evidence of the growing sophistication of the cybercrime infrastructure. A new report from Proofpoint describes how one organization employed third-party services, used technology and services to dynamically adjust to business challenges, and even created alternate revenue streams for itself.

The attackers began by buying lists of stolen administrator logins for WordPress sites from an underground marketplace. They then uploaded malware to those sites.

The attackers wouldn't serve up malware to just anyone who visited those compromised sites. First, they'd use a traffic distribution system filter (TDS) to check whether or not the incoming browser was a good target -- vulnerable, located in an attractive location, and not run by a security company scanning for nefarious activities. Further, they employed a third-party obfuscation service, Scan4U, to help avoid the notice of security companies.

Once a visiting browser was deemed satisfactory, the attackers would exploit the browser or one of the browser's plug-ins, and infect the client machine with a malware dropper via drive-by download. More clients were infected by distributing malicious content through the sites' email newsletters.

Over 500,000 client machines are infected, according to Proofpoint, but they estimate that as many as 2 million may have been compromised over the attack's full lifecycle.

Once the malware dropper was downloaded onto the client machine, the attackers would push down the actual payload -- usually the Qbot banking Trojan, but attackers could use the dropper to push out multiple pieces of malware to each host. The Scan4U service would alert the attackers whenever an anti-virus vendor detected their malware so they could re-obfuscate it. As the report states:

...the attack chain does not simply deliver a single piece of malware onto an infected system and stop at that. Instead, it is designed to establish a foothold on the system so that any number of different pieces of malicious software can be downloaded in order to carry out criminal activities ranging from banking account theft to secret communications and transfers, to distributed denial of service (DDoS), to ransomware and any other activity that represents an opportunity to monetize that infected system.

Qbot sniffed online banking "conversations" for credentials -- as many as 800,000, according to Proofpoint.

Proofpoint does not provide an estimate of how much money the attackers have made with those credentials, but they do state:

With 500,000 infected clients stealing online banking account credentials for as many as 800,000 online banking accounts, this cybercrime group has the potential for tremendous profits. Previous takedowns of rings of money transfer “mules” employed by organized crime groups have shown that $25,000 per account is a realistic figure. If even a fraction of a percent of the 800,000 accounts that they have sniffed yields credentials that enable them to conduct illegal electronic funds transfers (EFT) or other transfers this cybercrime group has the potential to net millions of dollars from their operation.

The crime group also created an alternative revenue stream for itself, by selling a tunneling service based on SOCKS5, called SocksFabric. The service lets customers build their own private cloud and provides them with easy infection points for their own attacks. The service costs $10 per day -- $100 for 30 days -- and includes a help manual.

The report continues:

The operations of this Russian cybercrime group exemplify both the sophisticated attack chain and the key challenges of modern threats. While attackers rely on a variety of means to connect with potential victims, compromised web sites are a critical component in the attack chain. Attackers have the financial and technical means to infect an almost unlimited number of legitimate web sites, above and beyond the more easily identifiable malicious or suspicious sites that traditional defenses are designed to detect and block.

See here for the full report.