Beware, There's A Bug That Makes Wi-Fi Connection Errors On IPhone

Wi-Fi connection on iPhone (9to5Mac)

Carl Schou, a digital security researcher from the non-profit group Secret Club, discovered that there are access points for Wi-Fi connections with names starting with the symbol percent (%). on iPhone and other iOS devices are not networked.

Carl also shared this finding via his personal Twitter account, @vm_call. In the tweet, Carl explained that any iOS device that tries to connect with the Wi-Fi network name %secretclub%power, is automatically disconnected from any internet connection.

You can permanently disable any iOS device's WiFI by hosting a public WiFi named %secretclub%powerResetting network settings is not guaranteed to restore functionality.#infosec #0day

— Carl Schou (@vm_call) July 4, 2021

Even, according to Carl, even his attempts to restart the device could not restore the network settings to their original state. The phone still cannot be connected by a Wi-Fi network or internet connection.

And the name of the Wi-Fi access point that Carl found wasn't just that. A few weeks ago, Carl and his team also discovered the existence of a Wi-Fi network with a similar name, namely '%p%s%s%s%s%n'.

At that time, Carl also found a similar condition. In fact, connectivity features such as AirDrop can't be used.

Beware If You See Wi-Fi Names Starting with '%'

Benjamin Mayo of 9to5Mac explains that the errors that occur when accessing the Wi-Fi network '%secretclub%power' and '%p%s%s%s%s%n' are closely related. Not the kind of error that happens by chance.

According to Benjamin, the two Wi-Fi access names are able to exploit errors in encoding the string format contained in the data structure that runs the iOS internet network. And apparently, now there are more variants of this bug.

“'% [character]' is a syntax commonly used in programming languages to format variables into output strings. In the C programming language, the '%n' specifier means to store the number of characters written into the format string to the variable passed to the function. The Wi-Fi subsystem may pass an unsanitized Wi-Fi network name (SSID) to some internal library — thus causing arbitrary memory writes," Benjamin wrote.

From a user perspective, the best way to prevent this bug is not to connect the device to a Wi-Fi network whose name contains a percent symbol. In addition, wait until Apple provides an update that contains the bug fix.