Wild iOS SSID Bug Disables iPhone Wi-Fi Even After A Reboot
Perhaps it is good to have a normal WiFi name or SSID, as one researcher found. Earlier this week, a new iPhone bug appeared that bricks any iPhone’s WiFi, if connected to a specifically named access point. While something like this could be used maliciously in theory, it would be hard to miss a hotspot named %p%s%s%s%s%n.
On June 18th, researcher and reverse engineer Carl Schou found that when he joined his personal WiFi with the SSID set to %p%s%s%s%s%n, it “permanently disabled its WiFi functionality.” Even a reboot or changing the SSID to something else would fix the problem, he tweeted. After some testing, it was eventually found that the only way to fix this would be to reset the device’s network settings under General>Reset>Reset Network Settings.
While it appears that Apple has not commented on the matter yet, researchers were quick to figure out that this could be a format string bug. Format strings are something of a placeholder for information within C-type languages, where they can be replaced with actual information, so you do not have to write extensive code for capturing or returning data. For example, you could have the line printf(“$1234”), or you could use the format specifier %d to do the same thing with printf(“%d”, 1234) where 1234 could be a variable.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
In this case, the code to handle a WiFi connection was not expecting format specifiers and subsequently broke in a spectacular fashion. Hopefully, Apple will have this fixed soon, but it is not the end of the world as if you join random WiFi networks, including ones named %p%s%s%s%s%n, you get what you deserve. Either way, let us know what you think of this interesting glitch in the comments below.
