Photo credit: NopSec
Posted on 07/22/2015 9:11:12 PM PDT by Swordmaker
The flaw allows attackers to exploit a Mac system for full privilege escalation and take over a machine.
(This vulnerability requires physical possession of the computer, and local Administrator access. It cannot be accomplished remotely or by a standard user. — Swordmaker)
A researcher has disclosed a privilege escalation vulnerability in OS X which is yet to be fixed in the latest release of the operating system.
German researcher Stefan Esser from security audit firm SektionEins disclosed the vulnerability on Tuesday. The security flaw affects OS X 10.10.x and relates to new features added by the iPad and iPhone maker in the newest evolutions of the OS, Yosemite and El Capitan.
The new features exploitable by the vulnerability are based upon the dynamic linker dyld and environment variable DYLD_PRINT_TO_FILE, which enables error logging to an arbitrary file.
"When this variable was added the usual safeguards that are required when adding support for new environment variables to the dynamic linker have not been used. Therefore it is possible to use this new feature even with SUID root binaries," Esser explained.
"This is dangerous, because it allows to open or create arbitrary files owned by the root user anywhere in the file system. Furthermore the opened log file is never closed and therefore its file descriptor is leaked into processes spawned by SUID binaries. This means child processes of SUID root processes can write to arbitrary files owned by the root user anywhere in the filesystem."
This, in turn, allows for privilege escalation and PC hijacking to take place.
The security researcher has released a full technical brief on the vulnerability, a working proof-of-concept (PoC) exploit -- and a warning that executing the code is a danger to systems as it installs a root shell.
Esser says it is "unclear" whether Apple knows about the security flaw or not, as it has already been patched in the first beta versions of OS X El Capitan 10.11, but not in the current release of OS X 10.10.4 or in the current beta of OS X 10.10.5, which has just been released to public beta testers.
The researcher speculates that the fix may be the result of a code cleanup rather than a security sweep, commenting:
"However, if this is the result of a security fix then Apple has once again shown how unsupported their current versions become the moment a new beta is in development."
Whether or not the tech giant knows about the flaw and is planning to release a patch, SektionEins has released the source code of a kernel extension and a digitally signed version which protects users from this vulnerability under the name SUIDGuard. You can download SUIDGuard from GitHub.
In July, Apple released a security update which patched dozens of security flaws in iOS 8.4 and OS X 10.10.4.
ZDNet has reached out to Apple and will update if we hear back.
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Okay, I'm stupid. I MUST be stupid because:
Where's the story here?
> till exists in OS X.10.4 and the seeded OS X.10.5 Yosemite
Don't you mean "OS X 10.10.4 and ... OS X 10.10.5 Yosemite"?
Nope. OS X 10.10.4 etc. is redundant. The name of Apple's operating system for the Mac is pronounced "OS Ten" the X is "ten", as in Roman numeral Ten. It's also a visual pun on UniX and NeXT.
That are all called OS X, OS "TEN". . . but, it's never pronounced OS "EKS".
What you're missing is that on a Mac, the Administrator account is not the highest level access. While I t's still limited, requiring name and password to do things and some things are still prohibited, the ROOT user is above Administrator level.
This vulnerability allows an admin to escalate his privileges by being able to open and write to ROOT-access-only files with impunity, regardless of what permissions are set on those files. That includes the files establishing who has access to what files, including ROOT files and who is a ROOT user! Privilege escalation from Admin to ROOT! Of course, on a Mac, the original Admin can create the first ROOT user and establish the ROOT password, so again, for most Mac users, this vulnerability is moot, because they could already do what it gives them the ability to do.
For some very limited number of Macs (I have trouble thinking of any, but it's possible) where an owner, who is the only one who knows the ROOT user name and password, has given admin privileges to one or two admins and some other users have only standard privileges, it might be a threat if one of the admins is too trustworthy. The it's an Oops!
That’s certainly what Malcom Ten calls it!
Democrats ask, “Is this white privilege?”
Another sign of a cult. Inventing your own secret language.
Not that I have heard. . . and that is not what Apple calls it. They've specifically use OS TEN in every comment they've spoken aloud about it. Only those who don't know use the wrong pronunciation. Even the numbering system is explained that way. It followed MacOS 9.
Steve Jobs announced it as OS TEN and never ever called it OS EKS.
Tell that to the Romans.
You mean the few that survived the demise of their cult? If I can find one I will.
OS X ( /oʊ ˌɛs ˈtɛn/), formerly Mac OS X, is a series of Unix-based graphical interface operating systems developed, marketed, and sold by Apple Inc. OS X is designed to run exclusively on Macintosh computers, having been pre-loaded on all Macs since 2002. OS X, whose X is the Roman numeral for 10 and is a prominent part of its brand identity, is built on technologies developed at NeXT between the second half of the 1980s and Apple's purchase of the company in late 1996. It was the successor to Mac OS 9, released in 1999, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 1984. Apple also uses 'X' in 'OS X' to emphasize the relatedness between OS X and UNIX. Definition of OS X from FreeBase
You can also just ask your Mac. Open the Terminal App and type "Say OS X" and it will respond: "OS TEN". That's pretty definitive.
Regardless of what the official pronunciation is, people say OH-ESS-ECKS all of the time. That’s a fact, just as people say Mizzuruh and Fujickle despite different pronunciations promulgated by authoritative sources.
Regardless of what the official pronunciation is, people say OH-ESS-ECKS all of the time. That’s a fact, just as people say Mizzuruh and Fujickle despite different pronunciations promulgated by authoritative sources.
And some people pronounce nuclear, "nukyuler," including a particular past President who shall go W'less. That doesn't make it correct.
Ignorance is it's own punishment. Thank God it's curable.
Well then, that's a tempest in a teapot...
Most of these are. . . and this one is particularly more of a tempest in a teacup, because anyone who has Admin privileges generally has the ability to create a ROOT user and password. It would be a very rare instance where they would not on a Mac. I can think of some instances where that MIGHT occur, but they'd be very rare on a single Mac. Usually anyone granted Admin privileges would have that ability. . . or they'd not even be trusted with Admin. Any other situations would be on networked Macs, and then it's highly unlikely that any single Mac user would have Admin privileges. Those would be with the Network Admin who'd also have ROOT access. This just is such a rara avis to be anything but only of interest to system programers because it DOES need to be plugged up.
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