‘Precursor malware’ infection may be sign you’re about to get ransomware, says startup

March 26, 2022 TH Author

Ransomware is among the most feared of the myriad cyberthreats circulating today, putting critical data at risk and costing some enterprises tens of millions of dollars in damage and ransoms paid. However, ransomware doesn’t occur in a vacuum, according to security startup Lumu Technologies.

A ransomware infection is usually preceded by what Lumu founder and CEO Ricardo Villadiego calls “precursor malware,” essentially reconnaissance malicious code that has been around for a while and which lays the groundwork for the full ransomware campaign to come. Find and remediate that precursor malware and a company can ward off the ransomware attack is the theory.

“The moment you see your network – and by network, I mean the network defined the modern times, whatever you have on premises, whatever is out in the clouds, whatever you have with your remote users – when you see any assets from your network contacting an adversarial infrastructure, eliminate that contact because that puts you in your zone of maximum resistance to attacks,” Villadiego told The Register.

If a company detects their network is contacting what looks like the command-and-control servers of malware, such as Emotet, Phorpiex, SmokeLoader, Dridex and TrickBot, shutting down those contacts right away “is going to eliminate the catastrophic effect, which is the ransomware attack,” he said.

Lumu outlined the idea of the warning signs of an impending ransomware attack in a quick report – what the company calls a “flashcard” – this month. In it the startup outlines what it says is a vicious cycle of ransomware.

Citing statistics from cybersecurity consultancy CyberEdge, Lumu said that victims that pay the ransom are increasingly recovering their data, from 19.4 percent in 2018 to 71.6 percent last year. This has made companies more willing to pay the ransom – 38.7 percent in 2018, 57 percent now – despite recommendations and pleas from the government and cybersecurity experts not to pay.

With more companies paying, threat groups are incentivized to run ransomware attacks and invest more money into their efforts, the Lumu researchers wrote, adding that result is more infections. Several US agencies – the Cybersecurity and Infrastructure Security Agency (CISA), FBI, and NSA – joined counterparts in the UK and Australia in February in issuing a joint advisory that indicated the threat of ransomware around the world will increase this year.

Addressing the precursor malware when it arises can reduce the incidence of ransomware, it’s claimed. Of the more than 2,000 companies Lumu monitors, every ransomware attack came with other malware preceding it and paving the way.

“When we see the companies that were affected, there were a lot of signs that were happening months – and in some cases, more than three months – before they were affected by the ransomware attack,” Villadiego said. “When you see a network that is contacting these precursors of ransomware, there are other pieces of malware that cause less harm.”

The precursor malware will spread laterally through a company’s network and devices, escalating access before a ransomware package is deployed, he said. Security pros within the company may see some kind of activity, and assume their firewalls or endpoint detection and response (EDR) software has caught it and protected them, whereas it’s just the precursor that was picked up. At the same time, a company’s security operations may be flooded with unrelated alerts that they are paying more attention to than that of the precursor malware, he said.

Meanwhile, the bad actors are being given months to set up a ransomware outbreak, the CEO said.

“What we make clear to the companies that we’re protecting is, your point of maximum resistance to attacks is your point of lesser contact,” he said. “Whatever that infrastructure is, that is going to be one of maximum resistance to attack … My advice to security operators is to deal with small problems so you don’t have to deal with a catastrophic event of a ransomware attack. And what is a small problem? A small problem in security is when your network is starting to contact these adversarial infrastructures, which typically goes unnoticed and typically doesn’t create an event that compels the operators to act.”

The company identified the malware backend that was most often detected being contacted. At the top of the list is Emotet, a banking trojan first discovered in 2014 that later evolved to include spamming and malware delivery services. Among the other malware were Phorpiex (a botnet first seen in 2016 that later included crypto-jacking and spreading ransomware), SmokeLoader (a backdoor for malware delivery), Dridex (known for stealing bank credentials) and TrickBot (a banking trojan).

Villadiego in 2018 founded Lumu, based in Doral, Florida. The company, which raised $7.5m in Series A funding a year ago and has about 80 employees, offers the Continuous Compromise Assessment model, which enables organizations to measure compromises within their systems in real time and automate the mitigation responses. The technology integrates with security tools enterprises are already using, delivers intelligence about compromises and lets organizations intentionally hunt for compromises.

Lumu assesses and collects information from such aspects as DNS queries, network flows, access logs, firewalls and proxies and correlates the data to identify whether any asset is trying to contact an adversarial infrastructure. Having that information enables organizations to end such contacts.

Enterprises are spending millions of dollars on security products and managed security services providers (MSSPs), but often their security teams are not looking for compromises.

“It’s hard to find something that we’re not looking for,” he said, adding that many assume that their organization is secure. “That is the wrong mindset and the breaches that have happened demonstrate that. A better way to operate is by assuming you’re compromised and let your network prove otherwise. Let the network prove you’re not.” ®