A bug revealed that the iPhone's Wi-Fi function can be completely disabled

A bug has been discovered in which the iPhone's Wi-Fi functionality completely fails when connected to a Wi-Fi network with a specific SSID.

A specific network name can completely disable Wi-Fi on your iPhone --9to5Mac
https://9to5mac.com/2021/06/19/a-specific-network-name-can-completely-disable-wi-fi-on-your-iphone/

Security researcher Carl Schou found a bug that caused the iPhone's Wi-Fi feature to stop working altogether . Schou reports on his Twitter account that connecting to a network with an SSID of '% p% s% s% s% s% n' will disable all Wi-Fi related features on the iPhone. ..

After joining my personal WiFi with the SSID “% p% s% s% s% s% n”, my iPhone permanently disabled it's WiFi functionality. Neither rebooting nor changing SSID fixes it :~) pic.twitter.com/2eue90JFu3

— Carl Schou (@vm_call) June 18, 2021

It is said that the Wi-Fi function is disabled on iPhone and iPad when connecting to the SSID '% p% s% s% s% s% n'. If the Wi-Fi function is disabled, it seems that 'AirDrop ', which exchanges data using Wi-Fi communication, will also be unavailable. In addition, it seems that disabling the Wi-Fi function will not be solved even if the terminal is restarted.

Schou doesn't explain in detail why connecting to the '% p% s% s% s% s% n' SSID disables the iPhone's Wi-Fi feature. However, 9to5Mac says, 'The syntax'% (alphabet)'is commonly used in programming languages to format variables into output strings, and in C the number of characters written in the format string is a string. It means converting to a variable that is passed to the format function, so it is possible that the Wi-Fi system has passed the unsanitized SSID to an internal library that is performing string formatting. It seems that this will cause arbitrary memory writes and buffer overflows, corrupting the memory, killing the process in iOS, and effectively disabling Wi-Fi. '

Therefore, until Apple fixes this bug, 9to5Mac recommends that if you find an SSID that contains '%' in free Wi-Fi etc., you should not connect to it.

If you accidentally connect to an SSID that contains '%' and the Wi-Fi function of your iPhone is disabled, tap 'Settings' → 'Reset' → 'Reset network settings'. It seems that you can cancel the disabling of the Wi-Fi function by resetting the network settings.