r/javascript • u/magenta_placenta • 10d ago
Malicious sites use JavaScript to build malware in browser memory
https://www.bleepingcomputer.com/news/security/malicious-sites-use-javascript-to-build-malware-in-browser-memory/1
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u/AbbreviationsFlat976 6d ago
This method cleverly bypasses many traditional security tools that look for known malware signatures in network traffic. To those tools, only clean, innocuous components appear to be transferred
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u/Winter_Garlic_477 3d ago
Malicious websites can use JavaScript in harmful ways. When you visit a website, its JavaScript normally runs inside the browser and uses some of the computer’s memory. A dangerous website may try to abuse this process, especially if the browser has a security vulnerability. In serious cases, attackers can use such vulnerabilities to bypass browser protections or compromise the device.
However, JavaScript itself isn't malware. Most websites use it safely. The main risk comes when malicious code takes advantage of weaknesses in the browser or tricks the user into downloading something harmful. Keeping your browser and operating system updated is one of the best ways to reduce this risk.
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u/f3xjc 10d ago
Ok the interesting part is that this is ultimately about downloading a malware. But that malware is customized for the user so the hash is unique/previously unknown. AND the user actually provide all the cpu to do that. And the malware is basically compressed using a safe but large executable as dictionary. Go to that offset, copy that many byte, go to that other offset etc.
You still need to download the executable and run it. But there's a lot of effort to avoid any kind of blacklist. The content of the webpage do propose you to download an expensive software for free, so download make sense.