This bug can permanently break iPhone WiFi connectivity

A new bug in iPhone can permanently break users’ WiFi by disabling it, the issue could be triggered by simply connecting to a rogue hotspot.

The researcher Carl Schou discovered a new bug in iPhone that can permanently break users’ WiFi by disabling it, the issue could be triggered by simply connecting to a rogue hotspot.

Once an iPhone established a WiFi connection to a rogue hotspot, it will no more be able to establish a connection to a Wi-Fi device, even if it is rebooted or the WiFi hotspot is renamed.

Schou noticed the issue because he had problems after logging into his personal WiFi hotspot named %p%s%s%s%s%n using his iPhone running iOS 14.4.2, but the expert noticed that the issue also impacts iPhone XS, running iOS version 14.4.2.

“This week, reverse engineer Carl Schou ran into an issue when connecting to his personal WiFi hotspot named:%p%s%s%s%s%n” reported BleepingComputer. “On connecting to the hotspot, his iPhone’s WiFi would be disabled, and every time he tried to enable it again, it would quickly turn off, even if he restarted the device or the hotspot name was changed.”

This kind of bug could have a severe impact in a real attack scenario that sees a threat actor setting up an open rogue WiFi hotspot in a crowded area such as a hotel hall or a station.

The only way to restore the Wi-Fi functionality was to reset the network settings of the impacted iPhone.

The experts confirm that the same attacks don’t work against Android devices.

Which is the root cause of this problem?

Independent security researchers speculate that the flaw could be caused by a parsing issue in the Wi-Fi settings.

Apple iOS may be misinterpreting the letters following the character “%” as string-format specifiers instead of considering it as part of the name of the specific hotspot.

How to restore Wi-Fi Connectivity on impacted iPhone devices?

The only way to restore a device is to reset your iOS network settings with these simple steps:

Go to Settings on your iPhone, select General.
Select Reset.
Select the ‘Reset Network Settings’ option, the device will reboot and network settings will be reverted to the factory default.

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Pierluigi Paganini

(SecurityAffairs – hacking, iPhone)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.