Cybersecurity researchers have uncovered a never-before-seen dropper that serves as a conduit to launch next-stage malware with the final word purpose of infecting Home windows methods with data stealers and loaders.
“This memory-only dropper decrypts and executes a PowerShell-based downloader,” Google-owned Mandiant stated. “This PowerShell-based downloader is being tracked as PEAKLIGHT.”
A number of the malware strains distributed utilizing this system are Lumma Stealer, Hijack Loader (aka DOILoader, IDAT Loader, or SHADOWLADDER), and CryptBot, all of that are marketed below the malware-as-a-service (SaaS) mannequin.
The place to begin of the assault chain is a Home windows shortcut (LNK) file that is downloaded through drive-by obtain methods — e.g., when customers search for a film on serps. It is value mentioning that the LNK recordsdata are distributed inside ZIP archives which are disguised as pirated films.
The LNK file connects to a content material supply community (CDN) internet hosting an obfuscated memory-only JavaScript dropper. The dropper subsequently executes the PEAKLIGHT PowerShell downloader script on the host, which then reaches out to a command-and-control (C2) server to fetch further payloads.
Mandiant stated it recognized completely different variations of the LNK recordsdata, a few of which leverage asterisks (*) as wildcards to launch the reputable mshta.exe binary to discreetly run malicious code (i.e., the dropper) retrieved from a distant server.
In an identical vein, the droppers have been discovered to embed each hex-encoded and Base64-encoded PowerShell payloads which are finally unpacked to execute PEAKLIGHT, which is designed to ship next-stage malware on a compromised system whereas concurrently downloading a reputable film trailer, probably as a ruse.
“PEAKLIGHT is an obfuscated PowerShell-based downloader that is part of a multi-stage execution chain that checks for the presence of ZIP archives in hard-coded file paths,” Mandiant researchers Aaron Lee and Praveeth D’Souza stated.
“If the archives do not exist, the downloader will reach out to a CDN site and download the remotely hosted archive file and save it to disk.”
The disclosure comes as Malwarebytes detailed a malvertising marketing campaign that employs fraudulent Google Search adverts for Slack, an enterprise communications platform, to direct customers to phony web sites internet hosting malicious installers that culminate within the deployment of a distant entry trojan named SectopRAT.
