According to the latest security research, it was found that certain Wi-Fi networks with the percent symbol (%) in their names can disable Wi-Fi on iPhones and other iOS devices. A tweet by Carl Schou, states that if an iPhone comes within range of a network named %secretclub%power, then they will be unable to use Wi-Fi or any related features. The issues will not end just at that, it’s also reported that even after resetting network settings, the bug may continue to render Wi-Fi services unable to use on the device.
Schou who belongs to his not-for-profit group, Secret Club that reverse-engineers software for research purposes, conducted research. And the result was that if an iPhone is connected to a network with the SSID name %p%s%s%s%s%n then it leads to a bug in iOS’ networking stack.
This bug would then disable its Wi-Fi, and system networking features like AirDrop would become unusable.
9to5 Mac offered a possible explanation for the weird bug, here’s the conclusion:
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) unsanitized 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.
Apple has been informed to rectify the above bug and for any new regrading, the solution stays tuned.
