“Cisco buried the lede.” >10,000 network devices backdoored through unpatched 0

On Monday, Cisco reported that a critical zero-day vulnerability in devices running IOS XE software was being exploited by an unknown threat actor who was using it to backdoor vulnerable networks. Company researchers described the infections as a “cluster of activity.”

On Tuesday, researchers from security firm VulnCheck said that at last count, that cluster comprised more than 10,000 switches, routers, and other Cisco devices. All of them, VulnCheck said, have been infected by an implant that allows the threat actor to remotely execute commands that run at the deepest regions of hacked devices, specifically the system or iOS levels.

“Cisco buried the lede by not mentioning thousands of Internet-facing IOS XE systems have been implanted,” VulnCheck CTO Jacob Baines wrote. “VulnCheck scanned internet-facing Cisco IOS XE web interfaces and found thousands of implanted hosts. This is a bad situation, as privileged access on the IOS XE likely allows attackers to monitor network traffic, pivot into protected networks, and perform any number of man-in-the-middle attacks.”

In an email, a VulnCheck representative said the company has “fingerprinted approximately 10,000 implanted systems, but we’ve only scanned approximately half of the devices listed on Shodan/Censys.” The number is likely to grow as the scan continues.

Although Cisco has yet to release a software patch, the company is urging customers to protect their devices. That means implementing a stop-gap measure to keep vulnerable devices from being exploited and running a host of scans to detect if devices have been backdoored.

“Cisco is committed to transparency,” a company representative wrote in an email Tuesday. “When critical security issues arise, we handle them as a matter of top priority, so our customers understand the issues and know how to address them."We are working non-stop to provide a software fix and we strongly urge customers to take immediate action as outlined in the security advisory.”