The QuickTime vulnerability disclosed in the Windows version of QuickTime last week also affects Mac OS X, Symantec said yesterday.
According to additional research by Symantec's security response team, the Real-Time Streaming Protocol (RTSP) bug in QuickTime is also present in the Mac versions of Apple's media player. "We tested it, and the [proof-of-concept] exploit does cause a denial of service," said Marc Fossi, manager of the Symantec team, explaining that the Windows-specific attack code fails to give a hacker access to a Macintosh but instead causes QuickTime to crash.
However, Fossi cautioned Mac users against believing that they are in the clear. "QuickTime vulnerabilities have tended to affect both Windows and Mac OS X, and it's always possible that a denial of service could lead to remote code execution," he warned.
Fossi also said that on Windows, it now appears that Microsoft's Internet Explorer Versions 6 and 7, as well as the beta of Apple's Safari browser, will offer some additional protection against attacks that are based on duping users into visiting malicious or compromised sites hosting rigged streaming content.
"The buffer overflow protection built into IE and in Safari prevents the exploit shell code from executing in the [QuickTime] plug-in," said Fossi. To successfully attack a user via IE or Safari, the current exploit example would have to be refined, Symantec added in a posting to its security blog Monday.
Firefox, however, provides no such protection, Fossi noted, because it passes off the streaming content request directly to the stand-alone QuickTime Player, ceding control to the Apple program.
Any attack on a Windows XP or Vista PC that circumvents the browser -- by delivering a rogue attachment that when opened automatically launches the QuickTime Player -- executes and compromises the computer, Symantec's research showed.
Fossi also repeated a warning given over the weekend that in-the-wild use of the exploit will probably come sooner rather than later. "When there is an exploit that's fairly complete, like this one, attacks could be soon in coming," he said. "It doesn't take someone very long to develop a malicious exploit when they start with something like this."
He recommended that network administrators block RTSP traffic -- the protocol's default outbound port is TCP 554 -- and that users steer clear of links to untrusted sites and be wary of file attachments.
Even though Apple has issued six QuickTime security updates so far this year and patched a total of 31 vulnerabilities, Fossi declined to call Apple's player less secure than those of rivals, such as Microsoft's Windows Media Player.
"Windows Media Player has had its share of vulnerabilities," he said. "A lot of people have media players installed on their computers, and they make pretty nice targets. Multimedia in general is a nice target for attackers. Most people know not to open a Word doc or an executable file, but with multimedia, everyone has a natural curiosity to see what their buddy just sent them.
Apple did not respond to questions about the QuickTime vulnerability and its plans for patching the program.