Damn Vulnerable Linux - The most vulnerable and exploitable distro • Hacker News Board

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#21

Post by davidw » Sat, Jul 17, 2010, 9:00 AM UTC

mahmud wrote: post #18

kaens wrote: post #16

Earlier quoted context omitted.

You wipe the disk and install OpenBSD.

Good idea, but completely beside the point.

Why sit around replacing packages by hand when you're not really learning anything? The best fix for a system like this is to nuke it from orbit and reinstall. I mean, odds are, you'll miss something, and then spent hours fooling around after getting hacked, when you could have just spent your time concentrating on what's important: saving relevant data and configuration, reinstalling, and securing the updated configuration.

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#22

Post by dfox » Sat, Jul 17, 2010, 11:06 AM UTC

derefr wrote: post #19

mahmud wrote: post #7

Earlier quoted context omitted.

You can't be bug compatible for things that violate the processor's protection protocol. Access to certain bits of the EFLAGS register is unavailable to unprivileged code. In fact. Just because you were allowed to raid and pillage by Microsoft for a few years doesn't mean it's the norm.

Sure you can—just let them stomp all over a virtualized processor/memory space.

You cannot meaningfully virtualize access to EFLAGS:IF. You can either emulate(/JIT) almost whole CPU or ignore this issue. And anyway, turning of interrupts is something that essentially does not make sense for user process, so it is better to just disallow that (which is what almost everything else but non-NT windows does)

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#23

Post by morazyx » Sat, Jul 17, 2010, 11:08 AM UTC

wwortiz wrote: post #4

That actually sounds like a fun concept.

Seems a decent educational tool too.. run in a virtual box and let your students go all out overflowing buffers and seeing the concepts in action. It comes with easy-to-follow guides.

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#24

Post by rick_2047 » Sat, Jul 17, 2010, 11:37 AM UTC

davidw wrote: post #21

mahmud wrote: post #18

Earlier quoted context omitted.

Good idea, but completely beside the point.

Why sit around replacing packages by hand when you're not really learning anything? The best fix for a system like this is to nuke it from orbit and reinstall. I mean, odds are, you'll miss something, and then spent hours fooling around after getting hacked, when you could have just spent your time concentrating on what's important: saving relevant data and configuration, reinstalling, and securing the updated config…

This is a course in security and thats why the comment is completely beside the point.

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#25

Post by JoeAltmaier » Sat, Jul 17, 2010, 1:37 PM UTC

pjscott wrote: post #3

sliverstorm wrote: post #2

> Damn Vulnerable Linux - The most vulnerable and exploitable operating system ever! Wait, they topped Windows 95 and Windows ME? Is that even possible?

I love how, on those OSes, you could freeze the whole thing solid with a three-byte program: cli # clears interrupts loop: goto loop This ballooned to a colossal four bytes if you put it in an EXE file, of course.

Any OS on that early hardware had this problem, right?

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#26

Post by JoeAltmaier » Sat, Jul 17, 2010, 1:39 PM UTC

dfox wrote: post #22

derefr wrote: post #19

Earlier quoted context omitted.

Sure you can—just let them stomp all over a virtualized processor/memory space.

You cannot meaningfully virtualize access to EFLAGS:IF. You can either emulate(/JIT) almost whole CPU or ignore this issue. And anyway, turning of interrupts is something that essentially does not make sense for user process, so it is better to just disallow that (which is what almost everything else but non-NT windows does)

It was usually used as an ultra- critical section. It would have been fine to simulate it as a scheduler-freeze for that process, preserving the meaning without getting hung up on the hardware implementation.

But instead, Intel decided to try to support actually messing with the interrupt enable state, resulting in years of highly-inefficient "solutions" e.g. trapping and simulating. Sigh.

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#27

Post by JoeAltmaier » Sat, Jul 17, 2010, 1:40 PM UTC

morazyx wrote: post #23

wwortiz wrote: post #4

That actually sounds like a fun concept.

Seems a decent educational tool too.. run in a virtual box and let your students go all out overflowing buffers and seeing the concepts in action. It comes with easy-to-follow guides.

OK for learning about what has been solved; kind of hacking-101. BUt the exploits involved have all been fixed in the products in that distro. What to use for the advanced class?

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#28

Post by JoeAltmaier » Sat, Jul 17, 2010, 1:40 PM UTC

morazyx wrote: post #23

wwortiz wrote: post #4

That actually sounds like a fun concept.

Seems a decent educational tool too.. run in a virtual box and let your students go all out overflowing buffers and seeing the concepts in action. It comes with easy-to-follow guides.

OK for learning about what has been solved; kind of hacking-101. BUt the exploits involved have all been fixed in the products in that distro. What to use for the advanced class?

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#29

Post by mfukar » Sat, Jul 17, 2010, 2:30 PM UTC

JoeAltmaier wrote: post #26

dfox wrote: post #22

Earlier quoted context omitted.

You cannot meaningfully virtualize access to EFLAGS:IF. You can either emulate(/JIT) almost whole CPU or ignore this issue. And anyway, turning of interrupts is something that essentially does not make sense for user process, so it is better to just disallow that (which is what almost everything else but non-NT windows does)

It was usually used as an ultra- critical section. It would have been fine to simulate it as a scheduler-freeze for that process, preserving the meaning without getting hung up on the hardware implementation. But instead, Intel decided to try to support actually messing with the interrupt enable state, resulting in years of highly-inefficient "solutions" e.g. trapping and simulating. Sigh.

What's the (efficient) alternative?

Re: Damn Vulnerable Linux - The most vulnerable and exploitable distro

#30

Post by nsfmc » Sat, Jul 17, 2010, 2:30 PM UTC

JoeAltmaier wrote: post #27

morazyx wrote: post #23

Earlier quoted context omitted.

Seems a decent educational tool too.. run in a virtual box and let your students go all out overflowing buffers and seeing the concepts in action. It comes with easy-to-follow guides.

OK for learning about what has been solved; kind of hacking-101. BUt the exploits involved have all been fixed in the products in that distro. What to use for the advanced class?

an actual distribution