Security Experts:

Neutrino Campaign Switches From CryptXXX to Locky Ransomware

A long-running exploit kit (EK) campaign has recently switched to distributing the Locky ransomware via the Neutrino EK, Palo Alto Networks researchers reveal.

The campaign has been running for several months, leveraging redirection gates registered through FreeDNS at afraid(.)org and employing various EKs for ransomware distribution. In February, the campaign was distributing Locky via Neutrino, and the actor behind it has switched back to that a few weeks ago.

The infection chain in this campaign is simple: cybercriminals compromise legitimate websites and inject them with code that leads the unsuspecting visitor to a redirection gate. Next, the victim is directed to the EK’s landing page, which attempts to exploit known vulnerabilities in popular software. Should it be successful, malware (in this case ransomware) is being installed on the victim’s computer.

Dubbed Afraidgate, the campaign has seen Locky being distributed via Nuclear in March, but its operators switched to Angler and CryptXXX in April. Ever since Angler disappeared from the threat landscape in early June, the campaign switched to Neutrino, but continued to serve CryptXXX as the final payload.

According to Palo Alto Networks’ Brad Duncan, July 11 was the last time CryptXXX was delivered as part of this campaign. Since then, Afraidgate has been serving Locky to unsuspecting users. Nonetheless, the delivered payload is the Zepto variant of Locky, which appends the .zepto extension to the encrypted files, the researcher says.

The new Locky variant emerged in late June, after the Necurs botnet was offline for around three weeks, which brought Locky and Dridex distribution to a near stop. When Necurs came back online, Locky returned strong: it had new anti-sandboxing and evasion techniques.

“Some security vendors have named this new variant Zepto ransomware, but they still highlight its similarities with the previous Locky variant,” Duncan notes.

Afraidgate is only one of the large-scale campaigns that switched to Neutrino after Angler died, with EITest and pseudo-Darkleech campaigns making similar moves. Neutrino, which is responsible for the largest EK traffic at the moment, accounts for the majority of ransomware infections via EK.

“Neutrino EK domains for this campaign tend to use .top as the top level domain (TLD). Otherwise, we see no surprises,” Duncan says. He also notes that the actors behind Neutrino and Locky are constantly changing domains, IP addresses, and other indicators associated with their malware.

Related: IE Exploit Added to Neutrino After Experts Publish PoC

Related: Locky Ransomware Sheds Downloaders in Favor of JavaScript

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