Microsoft Hacked: Joins Apple, Facebook, Twitter

Add Microsoft to the list of leading technology companies that have recently seen their employees' computers get hacked after they visited a third-party website devoted to iOS development.

According to a Friday "Recent Cyberattacks" blog post from Matt Thomlinson, general manager for trustworthy computing security at Microsoft, the company "recently experienced a similar security intrusion" to the attacks that penetrated the networks of Apple and Facebook.

"Consistent with our security response practices, we chose not to make a statement during the initial information gathering process," said Thomlinson. "During our investigation, we found a small number of computers, including some in our Mac business unit, that were infected by malicious software using techniques similar to those documented by other organizations. We have no evidence of customer data being affected and our investigation is ongoing."

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Thomlinson's short statement squares with what's already known about the attacks, based on previously issued public comments from Apple, Facebook and Twitter. Namely, in what's called a watering-hole attack, whoever launched these attacks first compromised the popular iPhoneDevSDK website, without tipping off the website's administrator, and then used the site to launch drive-by attacks against anyone who visited. The attacks, which targeted a zero-day vulnerability in the Java browser plug-in that's since been patched by Oracle, were obviously quite effective, because they affected OS X systems at Apple, Facebook, Microsoft and Twitter.

Microsoft's public statement also suggests that many more than just those four businesses may have been successfully compromised by attackers.

What were attackers seeking? One likely answer is that they were simply trawling for any customer data or proprietary company information that would have resale value on the black market, for example to better customize phishing attacks.

But Sean Sullivan, security advisor at F-Secure Labs, has also warned that the attackers may have had their eye on adding backdoor code -- that executes after a time delay -- into mobile iOS apps under development. "Apple and Google's app stores don't review source code, [they] just run the apps," said Sullivan via email. So, thinking like an attacker: "I would inject code that only enables itself in certain circumstances and at certain times (and build a botnet that way)," he said.

Accordingly, Sullivan recommends that all security managers review their employees' website-visiting logs to see if anyone visited iPhoneDevSDK, as well as review their mobile application code bases to look for unauthorized changes. In addition, any businesses -- and especially smaller organizations -- that thought they weren't a target should put a security plan to place to mitigate future zero-day attacks that target their developers. "They should be more proactive (paranoid) in the first place," Sullivan said. "Small startups probably mix work and play. They shouldn't. Buy your developers an additional laptop for just work."