Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Chinese Create Free App Store
Chinese Pirates have produced online App Store where you can download apps for free.
Their website 7659.com is essentially the equivalent app store without the fancy graphics. When you download an app from their site, it downloads the KuaiYong software which allows you to install pirated iOS apps onto your device without needing to jailbreak it.
How this site has stayed online is an oddity to everyone. Apple are well known for their fierce, robust piracy policy, offering take-down notices at the sniff of illegal activity. However, recently, Apple has taken caution when approaching China, for example when Tim Cook came under fire provoking state owned media for warranties – forcing an apology from him. Apple may fear that an aggressive response will cause problems which would be more than what it is worth.
The Chinese Pirates have not currently made an English translation of the site in an attempt to stay underground. They also use geo-location techniques to redirect your browser away from the download page. So unless you know Chinese and how to use proxies you won’t have any reason to illegally download Apps.