New Hosted Service Lowers Barriers to Malware Distribution

A newly discovered malware distribution operation that has been advertising its services on underground markets since late December 2017 is the latest example of the growing maturation of cybercrime as a service.

BlackTDS is a cloud-hosted traffic distribution system (TDS) for distributing malware. Security vendor Proofpoint, which has been tracking the service for the past several weeks, describes it as lowering the entry barrier for threat actors that want to engage in drive-by attacks.

The service isn't a completely turnkey one, since threat actors must still find a way to drive traffic to BlackTDS. "[But] it is otherwise a fairly complete solution, including social engineering for Web-based attacks that is fairly simple and inexpensive to configure and use," says Kevin Epstein, vice president of threat operations at Proofpoint.

A TDS is designed to take traffic from different sources; filter it based on parameters such as user agent, browser, and geography; and then redirect users to various websites, depending on their profile. Malicious distribution systems like BlackTDS use the parameters to redirect users of interest to specific malicious websites and payloads instead.

"For example, an actor might want to send Australian users who click on a malicious link in an email to a banking Trojan configured with injects for Australian banks but make sure that everyone else gets ransomware," Epstein explains.

The use of traffic distribution systems to distribute malware is not new. As far back as 2011, Symantec had reported on cybercriminals using a TDS to distribute exploit kits and malware to targets matching specific profiles. In 2016, Forcepoint reported on a threat actor using a malicious TDS dubbed BlackHat-TDS to redirect users to websites that hosted exploit kits.

As Forcepoint had noted at the time, threat actors running a TDS can set up blacklists of IP ranges to filter out traffic from security vendors and Web crawlers while ensuring traffic from ordinary users gets redirected to malware and exploits.

What makes BlackTDS different is that it is being delivered as a highly scalable, easy to deploy, and relatively inexpensive service. Threat actors can simply drive traffic to BlackTDS using spam, malicious advertisements, and other means; set up or provide access to their malware; and then let the service handle the rest of the distribution process.

"The actual redirection, filtering, and hosting of social engineering templates with connections to hosted malware or exploit kits, as well as the user-facing mechanisms behind drive-by attacks, all get handled by this single cloud-based service," Epstein says. "All the actor needs to provide is the traffic and payload or exploit kit access."

BlackTDS promises hosting that is difficult for researchers and sandboxes to identify and for anti-malware filters to automatically reject. BlackTDS is also relatively inexpensive, with some of its advertised services starting at $6 per day to $90 per month.

One indication of how effective BlackTDS has been so far is its use by TA505, a threat actor known for distributing ransomware and banking Trojans at massive scale. According to Proofpoint, TA505 recently used BlackTDS in a huge spam campaign designed to direct Internet users to a site selling discount pharmaceuticals.

TA505's use of BlackTDS shows the service is quite scalable and has attracted the attention of one of the most prolific malware distributors on the Web, Epstein says. "We can only speculate on the exact implications here, but we will continue to watch for the use of BlackTDS by TA505," he says.

For enterprises, services like BlackTDS once again reinforce the need for defenses at multiple layers such as the network layer, Web and email gateways, and endpoint devices, Epstein says. Attacks are becoming less dependent on active exploits than on user clicks, so education and training are critical as well, he says.

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