Security researchers observed the AZORult Trojan using a fake ProtonVPN installer to prey upon Windows users.

In mid-February, Kaspersky spotted a campaign in which digital attackers abused the ProtonVPN service to trick Windows users. Researchers at the security firm witnessed the campaign using malvertising techniques via affiliation banner networks as one of its infection vectors. These tactics tricked users into visiting counterfeit websites and downloading a fake ProtonVPN installer for Windows. Once downloaded, those installers infected users with the AZORult botnet.

Upon execution, the malware collected the environment information of the infected machine and sent it off to its command-and-control (C&C) server located at accounts[.]protonvpn[.]store. Malicious actors then used AZORult to steal various other details from their victims, including FTP logins, passwords, email credentials and even cryptocurrency from users’ local wallets.

AZORult’s Ongoing Evolution

News of this campaign comes after several rounds of innovation on the part of AZORult. Back in October 2018, for instance, Check Point observed a fresh version of the malware that came with a new means of connecting to its C&C server, an improved cryptocurrency wallet stealer and other changes.

This discovery came at around the same time that Palo Alto Networks spotted the malware as one of the primary payloads of the Fallout exploit kit in a campaign that researchers called “FindMyName.” More than a year later in February 2020, SANS’ Internet Storm Center discovered a campaign that used a triple-encrypted downloader to target users with AZORult.

How to Fend Off Fake ProtonVPN Malvertisements

Security professionals can help defend their organizations against malvertising campaigns, including those that use fake ProtonVPN installers, by keeping an eye on malvertising strategies and using threat intelligence to stay abreast of the latest campaigns leveraging these tactics.

Acknowledging malefactors’ frequent use of exploit kits in malvertising attacks, infosec personnel should also thoughtfully prioritize their organizations’ systems and functions so that they can create and maintain an effective patching schedule.