A security researcher has discovered a problem for Wi-Fi on iPhones and other iOS devices.
Carl Schou explained that certain Wi-Fi networks with the percent symbol in their names can disable Wi-Fi and related features on iPhones and even after resetting, there is a chance that the device will not connect to Wi-Fi.
He tweeted: "You can permanently disable any iOS device's WiFI by hosting a public WiFi named %secretclub%power. Resetting network settings is not guaranteed to restore functionality.#infosec #0day."
After Schou and his not-for-profit group, Secret Club, which reverse-engineers software for research purposes, first discovered issues with networks including the percent sign in their SSiD names, 9to5 Mac.com offered a possible explanation.
The publication stated: "the ‘%[character]’ syntax is commonly used in programming languages to format variables into an output string. In C, the ‘%n’ specifier means to save the number of characters written into the format string out to a variable passed to the string format function. The Wi-Fi subsystem probably passes the Wi-Fi network name (SSID) unsanitised to some internal library that is performing string formatting, which in turn causes an arbitrary memory write and buffer overflow. This will lead to memory corruption and the iOS watchdog will kill the process, hence effectively disabling Wi-Fi for the user."
