Researchers have discovered more than 130 malware samples designed to exploit the recently disclosed Spectre and Meltdown CPU vulnerabilities. While a majority of the samples appear to be in the testing phase, we could soon start seeing attacks.

The Meltdown and Spectre attack methods allow malicious applications to bypass memory isolation mechanisms and access passwords, photos, documents, emails, and other sensitive data. Shortly after Spectre and Meltdown were disclosed on January 3, experts warned that we could soon see remote attacks, especially since a JavaScript-based proof-of-concept (PoC) exploit for Spectre had been made available.

On January 17, antivirus testing firm AV-TEST reported that it had seen 77 malware samples apparently related to the CPU vulnerabilities, and the number had increased to 119 by January 23.

On Wednesday, AV-TEST told SecurityWeek that it has obtained 139 samples from various sources, including researchers, testers and antivirus companies.

“Most appear to be recompiled/extended versions of the PoCs - interestingly, for various platforms like Windows, Linux and MacOS,” Andreas Marx, CEO of AV-TEST, told SecurityWeek. “We also found the first JavaScript PoC codes for web browsers like IE, Chrome or Firefox in our database now.”

Fortinet, which also analyzed many of the samples, confirmed that a majority of them were based on available PoC code.

Marx believes different groups are working on the PoC exploits to determine if they can be used for some purpose. “Most likely, malicious purposes at some point,” he said.

The expert believes the current malware samples are still in the “research phase” and attackers are most likely looking for ways to extract information from computers, particularly from web browsers. He would not be surprised if we started seeing targeted and even widespread attacks in the future.

Processor and operating system vendors have been working on microcode and software mitigations for the Meltdown and Spectre attacks, but the patches have often caused problems, leading to companies halting updates and disabling mitigations until instability issues are resolved.

In addition to installing operating system and BIOS updates, Marx has two other recommendations that should reduce the chances of a successful attack: switching off the PC when it’s not needed for more than an hour, and closing the web browser during work breaks. “This should decrease your attack surface a lot and also save quite some energy,” Marx said.

Related: Fake Meltdown/Spectre Patch Installs Malware

Related: Intel Tests Performance Impact of CPU Patches on Data Centers

Related: Industry Reactions to Meltdown, Spectre Attacks