Router maker Zyxel tells customers to replace vulnerable hardware exploited by hackers

Taiwanese hardware maker Zyxel says it has no plans to release a patch for two actively exploited vulnerabilities affecting potentially thousands of customers. 

Threat intelligence startup GreyNoise warned late last month that a critical-rated zero-day vulnerability impacting Zyxel routers was being actively exploited. GreyNoise said the flaws allow attackers to execute arbitrary commands on affected devices, leading to complete system compromise, data exfiltration, or network infiltration.

The vulnerabilities were discovered by threat intelligence organization VulnCheck in July last year and reported to Zyxel the following month, according to GreyNoise, but had yet to be patched or formally disclosed by the manufacturer. 

In an advisory this week, Zyxel said it “recently” became aware of the two vulnerabilities — now formally tracked as CVE-2024-40890 and CVE-2024-40891 — which it says impact multiple end-of-life products.

The company claims that the flaws were not reported to it by VulnCheck and says it first became aware of them on January 29, a day after GreyNoise reported active exploitation.

Zyxel, whose devices are used by more than 1 million businesses, says that since these bugs affect “legacy products that have reached end-of-life [EOL] for years” it has no plans to release patches to fix them. Instead, the company is advising customers to replace vulnerable routers with “newer-generation products for optimal protection.”

In a blog post on Tuesday, VulnCheck notes that the impacted devices are not listed on Zyxel’s EOL page and says some of the affected models are still available for purchase through Amazon, which TechCrunch has confirmed.

“While these systems are older and seemingly long out of support, they remain highly relevant due to their continued use worldwide and the sustained interest from attackers,” Jacob Baines, CTO at VulnCheck, said. 

According to Censys, a search engine for Internet of Things devices and Internet assets, almost 1,500 vulnerable devices remain exposed to the Internet. 

In an update last week, GreyNoise said that it had observed detected botnets, including Mirai, exploiting one of the Zyxel vulnerabilities, suggesting it is being used in large-scale attacks.

Zyxel spokesperson Birgitte Larsen did not respond to TechCrunch’s multiple requests for comment.