Some Apple mobile users have been encountering a pop-up message that is particularly difficult to close.
The message appears after a user has been redirected to a different domain, usually caused by viewing a malicious advertisement, wrote Jerome Segura, a senior security researcher with Malwarebytes.
The message warns that a third-party application on the phone has caused the device to crash and includes a phone number where users can allegedly get their device fixed.
Warnings such as this one are employed by technical support schemes, which convince people to call their support lines by falsely warning that their computers or devices have security or performance problems.
"These scams rely heavily on social engineering, and crooks are always ready to defraud you of hundreds of dollars if you give them your credit card number over the phone," Segura wrote.
The fake warnings, which Malwarebytes first saw complaints about in late 2014, is easy to deal with on a desktop computer by closing the browser window. But on iOS mobile devices, it's a thornier problem.
Segura wrote that the pop-up message is coded to reappear every millisecond, making it nearly impossible for a user to do anything else with the Safari browser in the short interval.
"It's quite amazing that a few simple lines of code could cause such a massive problem and severe headaches among users," he wrote.
The message doesn't actually harm the mobile device, however. To get rid of the message, Segura wrote that users should put their phone into airplane mode, clear Safari's browsing history and then reopen the browser before disabling airplane mode.
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