4. Facebook Spotted Attack After Suspicious Network Behavior
While antivirus software didn't spot or block the attacks, other security defenses in place helped at least some of the businesses spot the exploit. Notably, Facebook said its security team spotted signs of an infection, which it then chased down. "In this particular instance, we flagged a suspicious domain in our corporate DNS logs and tracked it back to an employee laptop," according to Facebook. "Upon conducting a forensic examination of that laptop, we identified a malicious file, and then searched company-wide and flagged several other compromised employee laptops."
"After analyzing the compromised website where the attack originated, we found it was using a 'zero-day' (previously unseen) exploit to bypass the Java sandbox (built-in protections) to install the malware," said Facebook. "We immediately reported the exploit to Oracle, and they confirmed our findings and provided a patch on February 1, 2013, that addresses this vulnerability."
Similarly, Twitter's information security personnel had "detected unusual access patterns that led to us identifying unauthorized access attempts to Twitter user data," according to a blog post at the time from Bob Lord, Twitter's director of information security, who said that attackers accessed data that included "usernames, email addresses, session tokens and encrypted/salted versions of passwords."
5. Hacked Companies Circled The Wagons
Apple, Facebook and Twitter being attacked wasn't unusual, but according to Facebook, having such an attack succeed was rare. "Facebook, like every significant Internet service, is frequently targeted by those who want to disrupt or access our data and infrastructure," it said. "As such, we invest heavily in preventing, detecting and responding to threats that target our infrastructure, and we never stop working to protect the people who use our service. The vast majority of the time, we are successful in preventing harm before it happens, and our security team works to quickly and effectively investigate and stop abuse."
In the case of this successful exploit, Facebook said it immediately shared threat intelligence with other affected businesses, though didn't name them. "Facebook was not alone in this attack," it said. "It is clear that others were attacked and infiltrated recently as well. As one of the first companies to discover this malware, we immediately took steps to start sharing details about the infiltration with the other companies and entities that were affected. We plan to continue collaborating on this incident through an informal working group and other means."
Facebook, working with a third party, also sinkholed the command-and-control server employed by attackers, reported Ars Technica.
6. Warning: More Mobile Developers Likely Exploited
Who else might have been compromised as part of this attack campaign? F-Secure's Sullivan said in a blog post that because the attackers who compromised Facebook and Twitter did so via sites that target developers of mobile apps, all mobile app developers -- whether using Mac OS X or Windows -- should assume they've been targeted.
"Twitter and Facebook obviously have dedicated security teams on the lookout for trouble. (They're big targets.) Unfortunately, other smaller Silicon Valley startups (with big user bases) don't have the same resources," said Sullivan. "There are hundreds of thousands if not millions of mobile apps in the world. How many of the apps' developers do you think have visited a mobile developer website recently?"
What were attackers looking for? That's not yet clear, but if the hackers behind the exploits are criminals, then they're likely pursuing any avenue that could lead to remuneration. Unfortunately for mobile code developers, that might include efforts to sneak backdoors into their mobile apps. Accordingly, "any developer who has Java enabled in his browser, has visited mobile developer websites in the last couple of months and finds evidence his computer is compromised, probably should use his source code versioning system to check recent commits," said Sullivan. "And if you don't use a source code version system (such as SVN or Git), have fun re-reading your entire code base."