The report describes two serious software security holes affecting TCL brand television sets. First, a vulnerability in the software that runs TCL Android Smart TVs allowed an attacker on the adjacent network to browse and download sensitive files over an insecure web server running on port 7989. That flaw, CVE-2020-27403, would allow an unprivileged remote attacker on the adjacent network to download most system files from the TV set up to and including images, personal data and security tokens for connected applications. The flaw could lead to serious critical information disclosure, the researchers warned. Second, the researchers found a vulnerability in the TCL software that allowed a local unprivileged attacker to read from and write to critical vendor resource directories within the TV’s Android file system, including the vendor upgrades folder. That flaw was assigned the identifier CVE-2020-28055.
The researchers, John Jackson, an application security engineer for Shutter Stock, and the independent researcher known by the handle “Sick Codes,” said the flaws amount to a “back door” on any TCL Android smart television. “Anybody on an adjacent network can browse the TV’s file system and download any file they want,” said Sick Codes in an interview via the Signal platform. That would include everything from image files to small databases associated with installed applications, location data or security tokens for smart TV apps like Gmail. If the TCL TV set was exposed to the public Internet, anyone on the Internet could connect to it remotely, he said, noting that he had located a handful of such TCL Android smart TVs using the Shodan search engine.