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After celeb hack, Apple patches password guessing weakness in iCloud

On Monday Apple fixed a serious flaw in its iCloud service that could have been used by hackers to nab private celebrity pics leaked this week.

Anyone who’s scanned the news over the past 24 hours will now have read reports of around 100 female celebrities’ nude pics posted on the 4chan message board on Sunday, which have since spread across the web.

Some of the affected stars, most notably "Hunger Games" star Jennifer Lawrence, have confirmed the leaked images are genuine, while others on a supposed list of other victims, have denied their authenticity.

It’s not known how or when the photos were originally acquired, nor whether the unidentified leaker and hacker are the same person, but early reports pointed to iCloud as the possible weak link and on Monday the hunt for the culprit continued.

iCloud stores users contacts, photos, and media on Apple’s servers and can be accessed via a browser after entering the right username — an email address — and password combination. Users can also enable iCloud two-factor authentication, which should block attempts to access an account in the event credentials have been compromised.

Earlier this year, hackers hit Australian iPhone users with ransom demands after apparently using iCloud and its Find My iPhone feature to remotely lock down victims’ devices. In that case, Apple urged customers not to re-use passwords across multiple sites, suggesting hackers were using passwords leaked from other breaches to access iCloud accounts.

However, on Monday it emerged that flaw in iCloud's Find My iPhone feature could have allowed an attacker to guess an account's password multiple times — known as brute force attempts — without being blocked. Normally, websites that host password-locked information put a cap on the number of guesses someone can make before blocking further attempts.

Apple patched the flaw on Monday, but only three days after security researchers at HackApp published a proof of concept exploit for the flaw, aptly named ibrute, that HackApp claimed took advantage of an absence of protection against brute force attempts.

The tool used the top 500 passwords from the 2007 RockYou breach, which is still the world’s largest leak of plaintext passwords.

“It uses Find My Iphone service API, where bruteforce protection was not implemented. Password list was generated from top 500 RockYou leaked passwords, which satisfy appleID password policy,” HackApp says on its GitHub page.

For it to work, the attack tool would still require knowledge of a target’s email address, but while star’s generally don’t make their personal email addresses public, addresses are not exactly secret.

Whether or not the tool was used to breach the celebrities accounts isn’t known, however on Monday, HackApp reported that its ibrute tool no longer worked.

“The end of fun, Apple have just patched,” it said.

Apple has not confirmed it has patched iCloud, however, according to the Guardian, it was investigating whether there was an attack on iCloud but had no statement to offer.

HackApp on Monday told The Next Web that ibrute could have been used in the celebrity hack, but that it hadn’t seen evidence it was.

At the same time, there are a number of clues that iCloud may not be the source or at least not the only source of the leaked photos. As Reddit users noted, some of the pictures show victims holding Android devices, which could suggest another cloud service was hacked.

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