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Torvalds Creates Patch for Cross-Platform Virus
Newsforge is reporting that Linus Torvalds took a few minutes to review the cross-platform proof of concept virus covered yesterday and has proven that the virus does indeed not work with latest kernel version 2.6.16 and even released a patch in order to fix this "problem." From the article: "The reason that the virus is not propagating itself in the latest kernel versions is due to a bug in how GCC handles specific registers in a particular system call. [...] So the virus did a number of strange things to make this show up, but on the other hand the kernel does try to avoid touching user registers, even if we've never really _guaranteed_ that. So the 2.6.16 effect is a mis-feature, even if a _normal_ app would never care. It just happened to bite the infection logic of your virus thing."
Gotta admire how Linus calls a spade a spade even when that spade is a Good Thing. Imagine how MS would spin this if it happened to them.
I think you misunderstand. He fixed a flaw in the kernel that kept the virus from *working*. The patched systems should be vulnerable.
You say
...that linux was patched so that the virus would now function as expected? I'd hate to think we left any program behind.
as a patch or a bug or a buggy patch?
Next week: "Torvalds Patches Kernel Against Cross-Platform Virus"
what prevents each member of a programming group from having "complete mastery" of the kernel?
2 words:
middle management
...Rob
The American Dream isn't an SUV and a house in the suburbs; it's Don't Tread On Me.
Ok... now lets see Bill Gates issue his own patch. The clocks ticking Bill. :)
This is my sig. There are many like it but this one is mine.
Linus did not create a patch for the virus. Linus created a patch for the Linux kernel, to fix a bug which happened to have been discovered by looking at the virus.
Of course, if the story had been submitted with the correct title of "Linus fixes bug in Linux", it probably would never have been posted.
Tarsnap: Online backups for the truly paranoid
I don't want to get enfected with any of them Windows viruses, Mac Worms, or Linux Diseases.
So I run NetBSD
On a VAX
I'm slow, but I'm not infected.
(that's what I tell my girl also)
I know it was a proof of concept but... does the virus perform better on Windows or Linux?
Some of the "fanboys" are applying the new patch, and the rest are looking at the contents of your hard drive right now.
from TFA:
This lends support to the speculation that this virus is not new code at all, in spite of how Kaspersky Lab is trying to use it to drum up new business. [...] And shame on the anti-viral industry, Kaspersky Lab in particular, for its attempts to deceive the public by passing off old code as something new.
Newsforge is reporting that Linus Torvalds took a few minutes to review the cross-platform proof of concept virus covered yesterday and has proven that the virus does indeed not work with latest kernel version 2.6.16 and even released a patch in order to fix this "problem."
Oh, um... Well, hmmm.
Thanks, Linus. I guess.
m-
You catch enchiladas by picking them up behind the head and holding them underwater until they don't kick anymore -VeGas
Today, we fix Linux to support a cross-platform virus, tommorow: support for Windows viruses.
This is a really good insight, I think. While the rest of us are thinking about the "virus" and wondering what it means for the future, Linus identifies all these ignored technical aspects.
The power of a mind untouched by Slashdot?
Performance is only a small part of the issue. You have to look at the TCO of running viruses to appreciate Windows properly. With Linux it is far harder to run a virus and you've got to train all your users to chmod etc. With Windows it's much eaiser, just double click or drag and drop. Now that saves you a bundle in IT tech support when people ask "how do I install virus X on my PC. Further, with Windows you get a lot more choice. You can get a wide selection of popular viruses from easy to download sources. Linux is pretty short on choice, so if you switch to Linux you're limiting choice which is UnAmerican.
Engineering is the art of compromise.
AFIAK, there is no actual exploit in the code provided. The virus only does things that a regular program should be able to do, given the correct permissions.
The virus, written in assembly, calls the kernel via a depreciated interface (int 0x80 instead of syscall). It happens to have a value in the ebx register that it needs after the (buggy) system call.
The bug in the kernel is due to the fact that gcc assumes the system call doesn't change user registers (which the kernel isn't suppossed to as a policy) so gcc forms code to make the system call in less time (less instructions, less overhead) by not caring about user registers. The fix for the bug simply restores the value of the ebx register to what it was before the system call, hence the bug now works (as it has the correct value in the ebx register).
In fact, it would bite any program doing direct syscalls rather then using libc, so it might break linux handwritten asm code as well.