Bug Disables iPhone Wi-Fi Completely

A bug exists in the iPhone and is intended to be annoying, since it completely blocks the phone’s Wi-Fi. Fortunately, there is a fix if you find yourself in this situation.

Watch out for Wi-Fi networks and the iPhone

Security researcher Carl Shou discovered that the iPhone cannot connect to a Wi-Fi network at all if it has connected to a network named% p% s% s% s% s% n. All the Wi-Fi part no longer works, just like AirDrop. As can be seen in the video below, the button refuses to activate and therefore remains deactivated.

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

Obviously, such a network name is more than suspect from the start. It is unlikely that people would think of logging into it. But it is still important to report this bug. We can imagine that Apple will soon correct it with an update of iOS.

Why this bug, anyway? There is no official explanation yet. But one theory is related to the C programming language and% n. This element means that the number of characters written must be recorded. The Wi-Fi subsystem appears to transmit the Wi-Fi network name (SSID) without anonymizing it to an internal iOS library that performs a character-related operation, causing an arbitrary write to memory and a buffer overflow. This results in memory corruption and iOS closes the process, which completely disables Wi-Fi for the user.

How to fix the bug

What if you or a loved one has fallen for this bug and your iPhone’s Wi-Fi is completely blocked? You should know that a restart does not change anything. On the other hand, it is possible to go to Settings> General> Reset> Reset network settings. This will restore access to Wi-Fi. Be careful, however: this setting clears the list of all Wi-Fi points to which you have connected in the past. You will therefore have to identify yourself again with the box password when you log in for the first time.