Programmers have reintroduced a yawning security hole in Leopard, the latest version of Apple's highly regarded operating system, after having patched it more than 20 months ago in an earlier version, a researcher has warned.
The bug in Apple Mail makes it possible for attackers to run malicious code on a victim's machine by disguising an executable program as an image or other type of innocuous file, said Juergen Schmidt, editor-in-chief at Heise Security. A user can become infected simply by clicking on an attachment that looks like a jpeg image.
The bug is similar, if not identical, to one that Apple patched in March 2006, which also affected the Safari browser and iChat instant messenger program. The fix prompted Tiger, Leopard's predecessor, to inspect attached files and present a warning if the file a user clicked on was potentially unsafe.
Alas, that warning has largely vanished when Leopard users click on disguised executable files received in Mail, said Schmidt, who has set up a demo exploiting the bug here. About 90 percent of the time, he said, the file will run with no warning. He has yet to pinpoint what causes the dialog box to appear sometimes and not others.
"You would think that since they went to the trouble to fix it in Tiger, why reintroduce it in Leopard?" said Kevin Long, a researcher at Verizon Business, who specializes in security issues affecting Apple software. "The fact that they had done that before in Tiger and they didn't pro actively put that in Leopard is unfortunate."
Apple representatives didn't respond to a request for comment by time of writing. Apple has sold more than 2 million copies of Leopard to date.
Shortcomings in file validation have plagued Apple for some time now. The original bug resided in Mac operating systems for years before Apple finally patched the vulnerability. Even then, the security measure was criticized by some because it didn't work with third-party apps such as Firefox or Thunderbird and because OS X still made it easy to disguise malicious files as images.
Schmidt says he has not yet analyzed Safari or iChat to see if they properly validate files under Leopard but says "it's entirely possible" they don't
With one bound, Apple is free of 54 security bugs
Apple has rolled out software updates that patch just about everything but the kitchen sink. In all, there are fixes for at least 54 security bugs, many of which could allow attackers to remotely execute code on vulnerable Macs and Windows machines.
A whopping 41 vulnerabilities reside in OS X 10.4, which is better known as Tiger, 1of which 15 could lead to "arbitrary code execution". Buggy components include Safari, Kerberos, CFNetwork, AppleTalk, as well as the OS X kernel itself. The updates also fix a security hole in Apple's version of Adobe's Flash Player. Adobe has offered a update since July, but Apple is only now rolling it into its list of automatic updates.
The patch fest comes less than 48 hours after Microsoft released one of its sparsest monthly security updates in recent memory, with only one rated as critical. It also comes shortly after the discovery of a sophisticated port Trojan that targets Mac users.
"As Apple grows its market share and becomes a more mainstream operating system, there's going to be a lot more interest in it from the whitehats and the blackhats," said Randy Abrams, director of technical education at anti-virus provider Eset. "Apple users are going to have to get used to the same things that Microsoft and Unix users have dealt with for a long time and that's that patches are a fact of life."
A separate patch fixes three vulnerabilities for Leopard, the successor to Tiger that Apple released last month. The fixes appear to be tweaks to improve the security of the Leopard firewall. The patch, for instance, changes the description of one setting from "Block all incoming connections" to "Allow only essential services", so it's clear that mDNSResponder and other services continue to receive connections. Apple has also pared the processes permitted to receive such connections when the setting is turned on.
The Leopard fixes come two weeks after researchers from Heise Security criticized Apple for providing misleading firewall settings in the new OS.
"This is a good step forward in the right direction," Juergen Schmidt, Heise's editor-in-chief, said of the change. "I really appreciate it, that Apple did not take the smallest possible step to only change the name from "Block all" to "Allow only essential" but also drastically reduced the attack surface by allowing only a limited number of documented services to be reached."
By default, OS X is set to automatically check for the updates and prompt users to install them.
Apple also issued patches to plug 10 holes in the beta version of Safari for Windows. XP or Vista users who have installed the Apple software update application should receive a prompt to install the update. They can also do so manually by visiting this page.
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