Chinese router vendor denies its firmware contains backdoors – but pauses downloads to fix security issues anyway
It’s just a remote maintenance function, says Zbtlink
Chinese router manufacturer Zbtlink has vehemently denied accusations of its products containing backdoors, yet has implemented a temporary halt on firmware downloads for security reasons. The backdoor allegation surfaced after threat intelligence provider VulnCheck reported that a Zbtlink router they examined continuously attempted to connect to a command and control server.
Zbtlink's chief technology officer stated that the router's software, known as "ENDLESSDOORS," is an intentional feature for post-sales maintenance and is only present on sample units. The company clarified that this feature is not included in mass-production shipments and is primarily used for debugging purposes. Despite the company's assurances, Zbtlink's download page still listed the firmware for over 20 router models as containing the backdoor.
VulnCheck's CTO, Jacob Baines, expressed concern over the device's ability to connect to just four endpoints, which he deemed "damning." The security vulnerabilities were reported without following responsible disclosure practices, as Baines believed the situation warranted immediate action due to the potential for supply chain attacks.
He provided guidelines for users to block the router's connections and detect potentially compromised devices.
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