banner
Nov 25, 2021
15 Views
0 0

Stealthy new JavaScript malware infects Windows PCs with RATs

Written by
banner

Apple sues spyware-maker NSO Group, notifies iOS exploit targets
Over nine million Android devices infected by info-stealing trojan
Exploit released for Microsoft Exchange RCE bug, patch now
Malware now trying to exploit new Windows Installer zero-day
Windows 10 KB5007253 update released with network printing fixes
Black Friday Deal: Emsisoft Anti-malware on 3-devices for price of 1
Germany to force ISPs to give discounts for slow Internet speeds
Hackers exploit Microsoft MSHTML bug to steal Google, Instagram creds
Qualys BrowserCheck
STOPDecrypter
AuroraDecrypter
FilesLockerDecrypter
AdwCleaner
ComboFix
RKill
Junkware Removal Tool
How to remove the PBlock+ adware browser extension
Remove the Toksearches.xyz Search Redirect
Remove the Smashapps.net Search Redirect
Remove the Smashappsearch.com Search Redirect
Remove Security Tool and SecurityTool (Uninstall Guide)
How to remove Antivirus 2009 (Uninstall Instructions)
How to Remove WinFixer / Virtumonde / Msevents / Trojan.vundo
How to remove Google Redirects or the TDSS, TDL3, or Alureon rootkit using TDSSKiller
Locky Ransomware Information, Help Guide, and FAQ
CryptoLocker Ransomware Information Guide and FAQ
CryptorBit and HowDecrypt Information Guide and FAQ
CryptoDefense and How_Decrypt Ransomware Information Guide and FAQ
How to make the Start menu full screen in Windows 10
How to install the Microsoft Visual C++ 2015 Runtime
How to open an elevated PowerShell Admin prompt in Windows 10
How to Translate a Web Page in Google Chrome
How to start Windows in Safe Mode
How to remove a Trojan, Virus, Worm, or other Malware
How to show hidden files in Windows 7
How to see hidden files in Windows
eLearning
IT Certification Courses
Gear + Gadgets
Security
Malware
A new stealthy JavaScript loader named RATDispenser is being used to infect devices with a variety of remote access trojans (RATs) in phishing attacks.
The novel loader was quick to establish distribution partnerships with at least eight malware families, all designed to steal information and give actors control over the target devices.
In 94% of the cases analyzed by the HP Threat Research team, RATDispenser does not communicate with an actor-controlled server and is solely used as a first-stage malware dropper.
Going against the trend of using Microsoft Office documents to drop payloads, this loader uses JavaScript attachments, which HP found to have low detection rates.
The infection begins with a phishing email containing a malicious JavaScript attachment named with a ‘.TXT.js’ double-extension. As Windows hides extensions by default, if a recipient saves the file to their computer, it will appear as a harmless text file.
This text file is heavily obfuscated to bypass detection by security software and will be decoded when the file is double-clicked and launched.
Once launched, the loader will write a VBScript file to the %TEMP% folder, which is then executed to download the malware (RAT) 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.”
However, email gateways will detect the loader if the organization has enabled the blocking of executable attachments, such as .js, .exe, .bat, .com files.
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 (Windows Script Host).
HP’s researchers were able to retrieve eight different malware payloads from RATDispenser in the last three months.
The identified malware families are STRRAT, WSHRAT, AdWind, Formbook, Remcos, Panda Stealer, GuLoader, and Ratty.
In 10 out of the 155 samples analyzed, the loader established C2 communication to fetch second-stage malware, so while this is rare, the functionality is there.
In 81% of the malware drop cases, RATDispenser distributes STRRAT and WSHRAT (aka “Houdini), two powerful credential stealers and keyloggers.
Panda Stealer and Formbook are the only two payloads to be always downloaded instead of dropped.
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.
Fake end-to-end encrypted chat app distributes Android spyware
Chinese hackers use Windows zero-day to attack defense, IT firms
North Korean cyberspies target govt officials with custom malware
7 million Robinhood user email addresses for sale on hacker forum
These are the top-level domains threat actors like the most
Not a member yet? Register Now
Over nine million Android devices infected by info-stealing trojan
Malware now trying to exploit new Windows Installer zero-day
To receive periodic updates and news from BleepingComputer, please use the form below.
Terms of Use Privacy PolicyEthics Statement
Copyright @ 2003 – 2021 Bleeping Computer® LLC – All Rights Reserved
Not a member yet? Register Now
Read our posting guidelinese to learn what content is prohibited.

source

Article Categories:
Cybersecurity News
banner

Comments are closed.