Summary:
- These vulnerabilities affect: All current versions of OS X 10.5.x (Leopard) and OS X 10.6.x (Snow Leopard)
- How an attacker exploits them: By enticing one of your users to a malicious website
- Impact: An attacker executes code on your user’s computer, with that user’s privileges
- What to do: OS X administrators should download, test and install Security Update 2010-003 as soon as possible, or let Apple’s Software updater do it for you
Exposure:
Late Yesterday, Apple released a security update to fix a single security flaw that affects OS X 10.5.x and 10.6.x. The flaw resides in Apple Font Services (ATF), which is an OS X component used to handle and display embedded fonts. In short, ATF doesn’t properly handle specially malformed embedded fonts. If an attacker can lure one of your users into downloading or viewing a malicious document, perhaps embedded on a malicious website, the vulnerability can be exploited to execute code on that users computer with that user’s privileges. Since OS X separates the root user privileges from your basic user account privileges, an attacker can’t immediately exploit this to gain complete control of your Mac. However, he could leverage it to do anything on your computer that you can, so this still gives him significant access and control of your computer.
While this flaw lies within a font handling component, attackers will most likely exploit it through your web browser. In fact, that is exactly how the researcher who discovered this flaw, Charlie Miller, exploited it during this year’s Pwn2Own contest at the CanSecWest security conference. Miller lured his Safari victim to a malicious website containing an embedded font, which triggered this ATF vulnerability, and won Miller $10,000. As part of the contest, participants have to agree not to publicly disclose the flaws they use. Rather, they turn them over to TippingPoint, who doesn’t disclose them until the affected vendor fixes the issue. That means attackers in the wild probably do not know how to exploit this flaw yet. That said, its high publicity will surely bring it to the attention of attackers, so you should download and install Apple’s security update as soon as you can.
Solution Path:
Apple has released OS X Security Update 2010-003 to fix these security issues. OS X administrators should download, test, and deploy the corresponding update as soon as they can.
- Security Update 2010-003 (Leopard)
- Security Update 2010-003 (Leopard Server)
- Security Update 2010-003 (Snow Leopard )
Note: If you have trouble figuring out which of these patches corresponds to your version of OS X, we recommend that you let OS X’s Software Update utility pick the correct updates for you automatically.
For All Users:
This attack can arrive as normal-looking HTTP traffic, which you must allow through your firewall if your network users need to access the World Wide Web. Therefore, the patches above are your best solution.
Status:
Apple has released updates to fix this flaw.