Design/Logic Flaw

An issue was discovered in KaiOS 3.0 before 3.1. The /system/bin/tctweb_server binary exposes a local web server that responds to GET and POST requests on port 2929. The server accepts arbitrary Bash commands and executes them as root. Because it is not permission or context restricted and returns proper CORS headers, it’s accessible to all websites via the browser. At a bare minimum, this allows an attacker to retrieve a list of the user’s installed apps, notifications, and downloads. It also allows an attacker to delete local files and modify system properties including the boolean persist.moz.killswitch property (which would render the device inoperable). This vulnerability is partially mitigated by SELinux which prevents reads, writes, or modifications to files or permissions within protected partitions.