The same technology millions depend on to protect personal and confidential information — and that browsers highlight as crucial for secure browsing — is being used by threat actors to hide malicious payloads and criminal activity targeting corporations and individuals. And in many cases, organizations aren't doing anything to find out precisely what's going on inside their encrypted network tunnels.
Those are the conclusions reached in a pair of reports out just ahead of next week's RSA Conference, in San Francisco.
Gigamon ATR issued the "July-December 2018 Crimeware Trends Report" with a subtitle promising to tell readers "How The Most Prolific Malware Traversed Your Network Without Your Knowledge." Justin Warner, director of applied threat research at Gigamon, says the "how" is wrapped up in a simple statement: "What we discovered is you can't detect that you can't see."
Criminal use of encryption is the subject of Zscaler ThreatLabz report, "Zscaler Cloud Security Insights Report." "Everyone knows that the world is going to encrypted tunnels for privacy, but with the advent of free certificate providers, bad guys are able to take advantage, too," says Deepen Desai, vice president of security research and operations at Zscaler.
Gigamon's research found that encryption is being used by several "classic" malware families, including Emotet, LokiBot, and TrickBot. In fact, according to the Gigamon report, two-thirds of the malware detected in the study period was one of these threee types. The reason these malware families are still being used is simple, Warner says: They remain effective, and developing new malware is expensive.
"These threats are still succeeding. They're still effective. They do a lot of work to evade. They do change up how they look, but, in general, they're still using the same malware," he explains. "It is expensive for an adversary to change up their entire operation, but our goal as professionals in the intelligence and research space is to force these threats to take on that cost. That is really how we as an industry will better dismantle them."
Zscaler's Desai says the three levels of certificate validation — domain validation, organization validation, and extended validation — leave room for criminals to obtain certificates for sites that appear legitimate but are not. In domain validation, for example, all individuals have to do is show they are the owner of a particular domain; no checking is done to make sure they have the legal right to the name.
"Attackers will register a new campaign, do an aggressive spam or malvertising campaign, then move on because the domain ends up in reputation block lists," Desai says. According to the Zscaler report, in 74% of the sites that are blocked for security reasons, the certificate is short-term, valid for less than a year.
While free certificate authorities, such as Let's Encrypt, were launched to allow legitimate sites to be protected by SSL/TLS, they have been used by malicious actors, as well, and in huge numbers.
Desai is blunt about the consequences. "[As a result], we can no longer tell the users that the presence of a green padlock means you're visiting a safe site because the bad guys can get certificates, as well," he says.
According to the Zscaler report, 89% of the domains blocked on its networks for security reasons were encrypted with domain-validated certificates. The remaining 11% used organization validated certificates, while no sites employing extended validation certifcates were blocked.
While large enterprises see huge numbers of attacks, Gigamon's Warner says these visibility-based security issues aren't limited to big organizations. "These threats are not discriminatory — they're targeting businesses of all sizes and across verticals. They aren't picking any specific industry, and they aren't picking a specific target," he says.
At RSA, Desai says there will be two paths of discussion regarding these issues: the SSL certification side and traffic inspection. "On the SSL certificate side, there are more and more organizations moving away from domain verification certificates and going to higher verification, but we're still going at a slow pace," he says.
Both Warner and Desai say more organizations must be willing to build in processes and technologies to look inside the encrypted tunnels. With no safety in the green padlock, seeing as much as possible seems a necessary step to greater network security.
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