Mac OS X haunted by ghost of Jailbreakme bug

Older versions of Mac OS X are susceptible to a variation of the critical Jailbreakme vulnerability, which left Macs and Apple iDevices wide open to malware attacks, a security firm has warned.

According to Core Security, Apple has known about the bug in OS 10.5, aka Leopard, for two and a half months, but still hasn't fixed it. Members of the Boston-based company said they alerted Apple on August 26, and agreed to keep it private until a patch was issued. After Apple failed twice to meet patch deadlines, Core issued an advisory on Monday warning of the threat in the older OS, which unlike the more recent Snow Leopard, runs on Macs with PowerPC processors.

“According to information provided to us by Apple, a patch for this fix has already been developed,” the advisory stated. “Apple provided us a release date for this patch in two opportunities but then failed to meet their our [sic] deadlines without giving us any notice or explanation.”

The security input validation flaw resides in Leopard's Compact Font Format engine, which is used to render fonts. It can be exploited using a variety of methods, including by tricking a user to open a booby-trapped PDF file with the Mac's Preview document reader. The memory corruption exploit is triggered by manipulating the offset value of the CharStrings INDEX structure, Core said.

The code-execution bug is a variation of one that hackers from Jailbreakme.com used to jailbreak the iPhone 4. It didn't take long for security experts to realize the hole could also be used for malicious purposes. Apple killed the bug in iOS on August 11 and in OS X on August 26.

The same day the Mac update was released, Core alerted Apple that a variation, which has been dubbed CVE 2010-1797, afflicted Leopard. According to a detailed timeline included with Core's advisory, members of Core and Apple have been communicating back and forth about a release ever since. ®