Security News > 2021 > November > Stealthy new JavaScript malware infects Windows PCs with RATs

A new stealthy JavaScript loader named RATDispenser is being used to infect devices with a variety of remote access trojans in phishing attacks.

Once launched, the loader will write a VBScript file to the %TEMP% folder, which is then executed to download the malware payload. These layers of obfuscation help the malware evade detection 89% of the time, based on VirusTotal scan results.

"Although JavaScript is a less common malware file format than Microsoft Office documents and archives, in many cases it is more poorly detected. From our set of 155 RATDispenser samples, 77 were available on VirusTotal which allowed us to analyze their detection rates," explained the report by HP. "Using each sample's earliest scan result, on average the RATDispenser samples were only detected by 11% of available anti-virus engines, or eight engines in absolute numbers."

Another way to stop the infection chain from unfolding is to change the default file handler for JS files, allow only digitally signed scripts to run, or disable the WSH. Dropping malware.

"In 81% of the malware drop cases, RATDispenser distributes STRRAT and WSHRAT, two powerful credential stealers and keyloggers.

Overall, RATDispenser appears to accommodate the distribution of both old and new malware, serving as a versatile loader for threat actors of all skill levels.

News URL

https://www.bleepingcomputer.com/news/security/stealthy-new-javascript-malware-infects-windows-pcs-with-rats/