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Vista DRM Prevents Kernel Tampering
mjdroner writes "A ZDNet blog reports on a new DRM feature for Vista that 'protects' the kernel from tampering. The blog quotes a Microsoft document: 'Code (CI) protects Windows Vista by verifying that system binaries haven't been tampered with by malicious code and by ensuring that there are no unsigned drivers running in kernel mode on the system.' The blog says that much of the DRM in Vista is simply a port from XP, but that this feature is new to the OS."
Minifilter drivers don't have to be signed (at least in RC1 which is the last version I tried). That of course means you can get into ring 0 with a loadable driver - all that's needed is admin rights.
Modfying the kernel after that is just a matter of working out which bits (kill the code that checksums the binaries first, etc.)
What makes Sony's legitimate but the ones from Rootkit.com not?
If anything I would argue that rootkit.com is a more legit distribution mechanism than Sony.
"From: (Blair P. Houghton)
I predict that Eighth Generation computers
will compile no programs, run no applications,
and access no data. Instead they will be
designed and tuned to give a continuously
variable spectrum of elegant and precise
error messages describing your failure to
induce them to do so."
Yay Vista!
stuff |
How exactly would it accomplish this properly though? Call home periodically to get a kernel hash? Have a built-in hash check? If you want to allow the kernel to be updatable (which at times, is necessary), then you are going to have to allow the kernel to be "tampered with" somehow. A crack, virus, or other program might just masquerade as a patch to allow the on-disk kernel to be modified.
MS can't win for losing. Clearly the subversion of the kernel through rootkitting is a growing problem. If MS doesn't fix it, they get knocked for having no security. If they fix it, it is called DRM. Myself, I find Vista less than compelling. 2003 works just fine, but it seems some of the haters in the Slashdot crowd will see anything MS does as bad. They are finally getting their act together on not running everything as root and they even get knocked for that.
Cracking such a thing is trivial once you answer the question who watches the watchman?
As Apple just learned with their TPM kernel extension, all that hackers need to do is replace the binary that verifies all other binaries, and the "goodies" are up for grabs.
Obama likes poor people so much, he wants to make more of them.
The kernel mode signed driver restriction has already been broken by Blue Pill. Full details are in the black hat presentation, but the basic gist is you force a driver (eg null.sys) to be swapped out to disk, overwrite a function in the copy in swap with your own code, then call that function. And now you're executing unsigned code in kernel space.
The very idea of running software on my own equipment that considers me an enemy just doesn't sit at all well.
That, and I really like the Free Software TUN/TAP driver for Windows.
But aren't most spambot trojans business assets ? After all, spam makes money - that's why spammers bother - so rootkits are business assets for blackhat hackers, even more so than they are for Sony.
No, these poor hackers are simply trying to protect their right to profit - just like Sony. And if that means taking the control of the computer away from its owner, well, surely you agree that that's a small price to pay to ensure that those damn users aren't depriving them of those profits, right ? Sony certainly seems to...
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
This is not new (at least the concept) at all. We have been talking about this for years now. What do you think trusted computing (palladium) is? This has always been the "good" side of the TCPA coin, media DRM being the "bad" side.
Finkployd
This isn't just about supporting hardware. Several types of programs require kernel-mode drivers. Off the top of my head...
Installable file systems
Loopback mounts
Volume encryption
Rootkit detection
Packet sniffing
VPN software
I'm sure there are others. Vista's code signing requirement will make it difficult for any open-source program to do any of the things listed above. Large OSS projects backed by a company will probably be able to get a certificate from Microsoft and sign official builds, but third parties will be unable to modify and redistribute binaries, which is counter to the spirit of open source. I'm sure this is not an accident. Smaller OSS projects (such as installable file systems for ext3 or reiser) will most likely jsut disappear.
Because the target systems - even if in minority - only run Windows. For example, a small company writing drivers for an in-house server set. If they were concerned with security and cared about driver signing and such, then (a) they may not be able to afford getting the stuff from MS, and (b) they may not be able to turn off driver signing for the systems that will actually be using the drivers.
I wouldn't be surprised if domain policies were added to disable individual users from turning off driver signing - if that did happen, then there goes a lot of corporate R&D developers to the pot with not being able to develop drivers even for proof of concept stuff.
And yes, a lot of corporate companies won't buy something like this without first having some kind of proof of concept that what they are trying to accomplish with it works first. If their corporate governance decides they can't turn off driver signing - perhaps they are in the wrong division/etc but still need to do it - then they could be screwed. And the project won't happen.
Like it or not, there are valid reasons for removing this kind of DRM. It does cut out parties that could otherwise develop for you, and it can hurt pretty badly. This is undercutting a lot of the potential developers for MS. Now that might mean a greater groundswelling towards Linux, Mac, or something else, but it does hurt 3rd party developers and it does use their monopoly power in a wrong way that will disadvantage the industry.
Truth is like the sun. You can shut it out for a time, but it ain't goin' away. - Elvis Presley (source: imdb.com)
What is too keep microsoft or whoever from just saying nope your driver isn't good enough?
Nothing. Go to another signing-company, then.
I don't know about Vista, but XP has multiple root-certs from well-known signing companies pre-installed (verisign, etc). Pick one of them. If they all think that your driver "isn't good enough", then it probably isn't. BTW, "not good enough" usually means that they think the code in question is malware (win which case it's *good* that it be rejected) or piracy-ware (which would piss off the "information wants to be free" types) of some sort.
The other main reason for sigs is to ensure that a driver that you obtain wasn't mucked with. For example, if you download an ATI driver from some site and that driver has malware inserted into it, it likely won't have a digital sig, or at least not one that matches the driver or is valid, so it won't run.
-- "I never gave these stories much credence." - HAL 9000
No, an idiot is someone that thinks giving MS $500 and their rootkit-altering driver is a good way to make money. If MS doesn't find anything suspicious, your credit trail will certainly be easy enough to follow. Unless you think sending them $500 cash in an envelope with no return address will get the job done...
disclaimer: I've been known to store numbers in my ass for which to dig out when quantities are required.
Compare the two. If they match, then the file hasn't been tampered with... Tampering with this requires...
No, all that is required is to copy one key over the other in memory. Alternatively, one could modify a single comparison instruction in the loader. Then the match occurs, and the code will be allowed to load.
This is well within the range of an experienced hacker:
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