Cybercriminals are continuing to prey on users searching for cracked software by directing them to fraudulent websites hosting weaponized installers that deploy malware called NullMixer on compromised systems.
"When a user extracts and executes NullMixer, it drops a number of malware files to the compromised machine," cybersecurity firm Kaspersky said in a Monday report. "It drops a wide variety of malicious binaries to infect the machine with, such as backdoors, bankers, downloaders, spyware, and many others."
Besides siphoning users' credentials, address, credit card data, cryptocurrencies, and even Facebook and Amazon account session cookies, what makes NullMixer insidious is its ability to download dozens of trojans at once, significantly widening the scale of the infections.
Attack chains typically start when a user attempts to download cracked software from one of the sites, which leads to a password-protected archive that contains an executable file that, for its part, drops and launches a second setup binary designed to deliver an array of malicious files.
These malicious websites leverage search engine optimization (SEO) poisoning techniques such as keyword stuffing to feature them highly in search engine results. Similar tactics have been adopted by actors behind GootLoader and SolarMarker campaigns.
NullMixer, last month, was linked to the distribution of a rogue Google Chrome extension called FB Stealer, which is capable of Facebook credential theft and search engine substitution.
Some of the other prominent malware families distributed by the dropper include DanaBot and a raft of information-stealing malware such as ColdStealer, PseudoManuscrypt, Raccoon Stealer, Redline Stealer, and Vidar.
Also deployed using NullMixer are trojan downloaders like FormatLoader, GCleaner, LegionLoader (aka Satacom), LgoogLoader, PrivateLoader, SgnitLoader, ShortLoader, and SmokeLoader, as well as the C-Joker cryptocurrency wallet stealer.
Kaspersky said it blocked attempts to infect more than 47,778 victims worldwide, with a majority of the users located in Brazil, India, Russia, Italy, Germany, France, Egypt, Turkey, and the U.S. The threat actor operating NullMixer has not been attributed to a known group.
The latest findings are yet another indication that malware and unwanted applications are being increasingly propagated via pirated software. It's also recommended to check online accounts regularly for unknown transactions.
"Any download of files from untrustworthy resources is a real game of roulette: you never know when it will fire, and which threat you will get this time," Kaspersky researcher Haim Zigel said. "Receiving NullMixer, users get several threats at once."