The North Korean risk actors behind the Contagious Interview marketing campaign have as soon as once more tweaked their techniques through the use of JSON storage providers to stage malicious payloads.
“The risk actors have just lately resorted to using JSON storage providers like JSON Keeper, JSONsilo, and npoint.io to host and ship malware from trojanized code initiatives, with the lure,” NVISO researchers Bart Parys, Stef Collart, and Efstratios Lontzetidis mentioned in a Thursday report.
The marketing campaign primarily entails approaching potential targets on skilled networking websites like LinkedIn, both beneath the pretext of conducting a job evaluation or collaborating on a mission, as a part of which they’re instructed to obtain a demo mission hosted on platforms like GitHub, GitLab, or Bitbucket.
In a single such mission noticed by NVISO, it has been discovered {that a} file named “server/config/.config.env” accommodates a Base64-encoded worth that masquerades as an API key, however, in actuality, is a URL to a JSON storage service like JSON Keeper the place the next-stage payload is saved in obfuscated format.
The payload is a JavaScript malware often called BeaverTail, which is able to harvesting delicate information and dropping a Python backdoor known as InvisibleFerret. Whereas the performance of the backdoor has remained largely unchanged from when it was first documented by Palo Alto Networks in late 2023, one notable change entails fetching a further payload dubbed TsunamiKit from Pastebin.
It is price noting that use of TsunamiKit as a part of the Contagious Interview marketing campaign was highlighted by ESET again in September 2025, with the assaults additionally dropping Tropidoor and AkdoorTea. The toolkit is able to system fingerprinting, information assortment, and fetching extra payloads from a hard-coded .onion deal with that is at present offline.
“It is clear that the actors behind Contagious Interview are usually not lagging behind and are attempting to forged a really extensive internet to compromise any (software program) developer which may appear attention-grabbing to them, leading to exfiltration of delicate information and crypto pockets data,” the researchers concluded.
“The usage of respectable web sites corresponding to JSON Keeper, JSON Silo and npoint.io, together with code repositories corresponding to GitLab and GitHub, underlines the actor’s motivation and sustained makes an attempt to function stealthily and mix in with regular site visitors.”
