Researchers from Trustwave have discovered a backdoor in IoT devices manufactured by a Chinese vendor that is refusing to fix it.
The backdoored devices are produced by the VoIP firm Dbltek, the researchers speculate the backdoor was introduced for debugging purposes.
The experts discovered that the Telnet interface of the GoIP has an undocumented user, namely “dbladm,” which provides root level shell access on the device. The account is not protected by a password, instead, it is protected by a proprietary challenge-response authentication scheme.
When the attacker tries to Telnet into the device as dbladm, the IoT component tries to connect to UDP port 11000 on 192.168.2.1 on the local network. If the flawed device receives a valid response, it grants access.
“Trustwave recently reported a remotely exploitable issue in the Telnet administrative interface of numerous DblTek branded devices. The issue permits a remote attacker to gain a shell with root privileges on the affected device due to a vendor backdoor in the authentication procedure.” reads the analysis published by Trustwave.
The researchers ethically reported the issue to the IoT vendor, but the manufacturer issued a new firmware with minor changes that leave the access open.
Dbltek then has closed any contact with Trustwave that has continued the analysis of the backdoor and has written the PoC exploits for the backdoors in both the old and new firmware versions.
The flawed firmware is present in almost all Dbltek GSM-to-VoIP devices that are mostly used by small to medium size businesses.
An internet scan for vulnerable devices revealed the existence of hundreds of devices online.
(Security Affairs – Dbltek, VoIP )
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.