Slashdot Mirror
Is the x86 Architecture Less Secure?
An anonymous reader asks: "Paul Murphy at CIO Today reports that a specific Windows buffer overflow vulnerability ' depends on the rigid stack-order execution and limited page protection inherent in the x86 architecture. If Windows ran on Risc, that vulnerability would still exist, but it would be a non-issue because the exploit opportunity would be more theoretical than practical.' And implies that other Windows vulnerabilities are actually facilitated by having an x86 chip." How does the x86 processor compare with other architectures when it comes to processor based vulnerabilities? How well have newer additions, like the Execute Disable Bit, helped in practical situations?
all x86 processors have an evil bit
Paul Murphy, I'd like you to meet Paul Graham. What we have here is an Apple press release being printed up as a trade journal article.
Good for Apple's PR firm. I guess.
Not that I have anything against Macs or PowerPC hardware, I just don't like disengenuous authors (or their articles).
Regards,
Ross
What, is there only one tech writer in the world? (See article two or three down on SCO)
If windows Ran on a RISC arch then it would be just as insecure . .If you know of a flaw in your architecutre then why are you programing
The fact is not that this issue is an insecurity in X86 but the fact that windows uses it
to that flaw .
The only things certain in war are Propaganda and Death. You can never be sure which is which though
2 articles in under 4 hours submitted by an "anonymous reader" that point to Paul Murphy at CIO Today. Hmmmm... Astroturf anybody?
"I'd rather be a lightning rod than a seismometer." -Ken Kesey
Blame the machine or blame the programmer? You can write x86 code without buffer overflows, period. That you can be more sloppy on other architectures and not get overflows seems silly. Like "everyone should drive Volvos cause they are safer."
Lots of things can be laid at the feet of x86 architecture, but not that it seduces programmers into writing code with buffer overflows.
"Eve of Destruction", it's not just for old hippies anymore...
If Windows ran on Risc, that vulnerability would still exist, but it would be a non-issue because the exploit opportunity would be more theoretical than practical.
Funny how exploits that are "just theoretical" don't stay that way forever...
Wer mit Ungeheuern kämpft, mag zusehn, dass er nicht dabei zum Ungeheuer wird. --Nietzsche
On x86, the stack grows backwards. Backwards! A stack overflow ought to overwrite unallocated space, not earlier stack frames and return addresses. It's totally insane.
But I guess when you live with insanity year after year, you get used it.
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
But doesn't pretty much everyone use a compiler. And doesn't the compiler pretty much insulate you from such issues? What am I missing?
"Eve of Destruction", it's not just for old hippies anymore...
The real disadvantage of x86 over a RISC architecture like SPARC is that it doesn't have page protections (not to be confused with real mode segmentation which essentially disables the protected mode i386 MMU) where pages containing data and code are marked differently, so data pages are non-executable. sparcv9 implements a non-executable user stack per default, whereas it's a configurable option for sparcv8 binaries.
This has all changed with x86-64/AMD64/EM64T/x64/WHATEVER, which has brought a noexec bit to memory pages and allows hardware buffer overflow protection similar to SPARC. This still isn't a silver bullet for buffer overflows, but it's certainly better than nothing.
Still here? Dammit...
SIG: HUP
..so what if I have 0.999997 viruses in my CPU?
Thanks, Slashdot -- I actually read that boatload of ignorant gibberish, and now I'm measurably dumber than I was before I clicked the link. Keep this up and I too will be making specious arguments about "RISC" and "CISC".
To spur "enterprise Linux," Big Bang, the distributed two-phase commit.
SO! We now know the truth: Microsoft is blameless for the shoddy security of their products. It's all the fault of the x86 architecture.
After all, how could Microsoft be expected to learn the intricacies of their primary platform and write code that does what it's supposed to?
We have been lied to.
Intolerance for ambiguity is the mark of the authoritarian personality.
For starters, Windows does run on RISC.
The stack behaviour of PowerPC is just as predictable as x86, and it's just as easy to perform a buffer overflow attack on vulnerable code.
PowerPC doesn't offer more per-page protection than x86, and it offers less than x86-64, as x86-64 can disable execution on a per-page basis.
It's possible to do things on both architechtures like add a random offset to the stack or load libraries at random locations. This makes attacks much more difficult, and OSes like OpenBSD do them on both architechtures. OSes like Linux or MacOS don't do them on any architechtures. Stack protections like propolice are a compile-time option and can be used on any OS on any architechture.
The mainstream architechtures of today do very little to distinguish themselves from each other security wise. One of the the few features that is different from one architechture to another, per-page execute protection, is not available on PowerPC.
This guy doesn't know what he's talking about.
I rarely criticize things I don't care about.
Linux, BSD, and other *nix systems are reasonably well protected through the design of the system and the widespread use of common server programs, which are checked and re-checked for these problems by a variety of people and organizations. Also, GCC provides ProPolice, which can help lock things down a bit more. I think this particular problem mostly applies to systems running Windows.
Microsoft's business problem in this regard is that they have no control over the applications running in Windows, and they provide a default Windows install that is quite open and vulnerable. Locking down the ports and getting rid of the most dain-bramaged policies in Windows is only one part of the solution. Vulnerabilities in application programs can still be used to break into these systems, and Microsoft will ultimately be blamed.
Perhaps the best thing Microsoft can do is integrate something like ProPolice into the C and C++ libraries used to compile programs for Windows. This would make a big difference in protecting the stack of running programs that are not designed with security as a priority.
If x86 really is less secure by nature, it probably wouldn't hurt if they'd put their virtualization engine (similar in function to VMware but not even half as good) right into the core OS. Under such a design, only the Windows kernel would run directly on the processor; the rest of the operating system and all of the application programs would run with the same x86 instruction set, but through the virtualization engine. There, checks could be made to prevent the most common vulnerabilities of the x86 processor from being utilized.
while the NX bit can help prevent the execution of malicious code on the stack after a buffer overflow, it doesn't solve the security problem posed by overflows. return-into-libc attacks can easily be executed and will become much more prevelant as NX-enabled PCs filter into the mainstream. address space randomization can help make rilc attacks harder on 64-bit architectures but is pretty useless on 32-bit archs.
Paul, let me explain how to be an industry analyst... 1) NEVER NEVER NEVER refer to anything that puts Microsoft in a bad light. After all, they pay the bills. 2) NEVER NEVER NEVER mention pinko-commie-bastard linux without mentioning how the TCO is lower on Windows, reliability is a myth, and security is virtually non-existent. 3) Lastly, land a gig working for a real tech think-tank, like the Yankee Group (TM). CIO Today? Who reads that rag anyway? You get more press from these slashdot lusers than you do from a bunch of clueless pointy-haired bosses. Love, Laura Groom of the Stool to Lord Bill
Althought the insecurity of code that is only 'theoretically' exploitable ought to be fixed (we all prefer bug free code, right?) many theoretical exploits will never be practically exploited for technical reasons.
There is a distinction here which needs to be made between code which is exploitable but for which no public exploit code or method has been released -- in which cases it 'wont stay that way for ever' -- and code wherein the calculation of an arbitrary or runtime offset (e.g for a buffer overflow) is impossible and guesswork is impractically unlikely. Theoretical insecurities of the latter type are very likely to 'stay that way for ever'
use Blunt::Instrument;
Did you happen to actually read the article? The guy ends by blatantly stating that there is no sane reason to choose a PC over a mac. How can you possibly see this guy as an MS supporter,.. unless of course you didn't really read the article.
Except by VMware and Virtual PC. Oh wait, I guess it can be virtualized!
I just read this article recently in Embedded Systems Programming magazine. http://www.embedded.com//showArticle.jhtml?article ID=55301875
After a detailed explanation of the hardware protection features built into the x86 (since the 80386), the author makes the following statement towards the end of the article:
"Too bad Microsoft doesn't use this feature. Windows has been plagued by buffer-overflow bugs that could easily be prevented by the processor's segmentation features. Alas, even though these features have been built into every x86 chip for more than 15 years, Microsoft has never used them. Instead, Windows creates a "flat" memory system with no segmentation, no tasking, no bounds checking, and no privilege protection, and then struggles to duplicate all those features in software. The result has been famously ineffective."
Check Raymond Chen http://blogs.msdn.com/oldnewthing/archive/2004/09/ 14/229387.aspx
Using a segmented address space, where the Stack and Code are kept in what are effectively different address spaces, would do much to mitigate the effect of buffer overruns. On the other hand, the NX bit on x86-64 accomplishes basically the same thing, without the overhead of having to use long pointers to access data on the stack.
Neither of them are really all that robust though, since any time you can overwrite the return address on the stack, you can cause execution to veer off to somewhere else. Maybe you won't be able to insert shellcode into the program's address space, but if you can cause a function to "return" to something in the C standard library, like remove(), you can still cause havoc.
A more secure solution would split the stack such that function arguments and return addresses are not stored in the same space. This would give you a somewhat Forth-like runtime model, where return addresses are stored on one stack, and data values on the other. In that case, a buffer overrun in one function would still allow you to overwrite the arguments to another function, which is sub-optimal.
If you combine a split stack with growing the stack in the non-obvious direction, then you're probably as secure as you're going to get without eliminating the use of a stack altogether.
-Mark
Anyway, you forget, this is slashdot - car analogies get mod points.
Yes, but only cdr analogies get +1, Funny.
The stack direction has nothing to do with security. You can still have stack protection running up or down stacks. Once you have a reasonable MMU, all further problems are due to software design.
Engineering is the art of compromise.
I think a future version of X86 should have virus execution assistance in hardware.
Given that you just can't stop the things, why not offload the burden of running them from the processor?
BIPs (Bots Infected per Second) could be the metric for performance.
CAN-2004-1134 is a buffer overflow issue. The Mac is susceptible to buffer overflows.
Take e.g. the iSync issue. Apple doesn't go into details, but if you do a Google search on "isync vulnerability" you will find:
"The vulnerability is caused due to a boundary error in the handling of the "-v" and "-a" command line options. This can be exploited to cause a buffer overflow by supplying an overly long argument (over 4096 bytes). Successful exploitation allows execution of arbitrary code with the privileges of the mRouter application."
A proof of concept exploit can be found at. It opens a root shell.
When the PowerPC jumps to a subroutine, the return address is stored in the lr register. The first thing the prolog code in the subroutine does, is to put the address on the stack (freeing up the register for further function calls). So, a would-be hacker can overwrite the return address. For a description of how to take advantage of buffer overflows on the Mac, see "Smashing The Mac For Fun & Profit".
Xix.
"Everything is adjustable, provided you have the right tools"
Nowday, what I see on the news are stories
about Michael Jackson, Mrs. Stuart, and the Pope.
This is what is passed as "news". Is the
media biased towards the left or towards the
right? When all they do is talk about
the unimportant, the media is not biased at
all! They are just silly.
- The telnetd AYT heap overflow (2002) could be exploited on x86/*BSD systems specifically because of their memory layout and little-endianess, while MIPS and SPARC systems were saved by their big-endian, 64bit addresses. Yet, on x86/Linux it was not exploitable, because of a different memory layout within the heap.
- The Solaris login heap overflow (2001) could be exploited on both x86 and SPARC. The reason were that addresses are created by the vulnerable code itself.
- The SSH1 CRC32 overflow (2000), has been exploited on every known architecture, x86, SPARC, MIPS, etc. because the data used to overwrite memory with were created by the vulnerable code itself, hence endianess and order did not matter.
Now, there are cases where RISC architecture makes exploitation more difficult to impossible. But there are around an equal amount of cases where x86 is saved. But the reason is not to be found within the architecture alone, but within differences in the whole chain from CPU to process memory layout to ABI and runtime environment. The following are especially important to determine if a vulnerability could be exploited on a given system:- CPU, word width and endianess
- process address layout
- stack frame handling and layout, how registers are saved (register windows?) order of registers/parameters/locals/alloca
- heap handling (i.e. what malloc allocation system is used. For example, most *BSD systems use an out-of-chunk management to control the heap structure itself, while glibc uses an inband management, which is by nature more likely to allow exploitation)
- compiler optimizations, eg. if small functions are inlined omitting stack frames, etc.
- ...
Speaking with more than eight years of exploit development experience, there is much more to consider than just the CPU type.it's a known issue that the intel x86 platform is vulnerable to stack-based buffer overflow exploits. the amd64 architecture is addressing this by providing hardware page protection which prevents code from being illegally executed off the stack. netbsd has enabled this feature by default in netbsd 2.0. i look at the x86 platform like training wheels and amd64 like a nice racing bike... ;-)
But it's tough to run C on that kind of architecture. C wants pointers to be addresses. The "array is a pointer" convention is a bad fit to a true segmented architecture. You can run Pascal just fine, but running C is tough. It can be done, but basically requires allocating all the variables in one big "array" at the hardware level, so you lose the protection. When C came in, the Burroughs machines (by then the Unisys A series) died off.
So it's quite possible to fix this, but you have to dump C. This may happen as Java and C# get more traction.
C++ doesn't help. It's part of the problem.
http://cvs.openbsd.org/papers/auug04/
Theo talks about how OpenBSD uses various available processor features to increase system attack resilience, w/minimal performance impact. The design choices made for architectures with differing degrees of per-page protection are presented. The concepts are not at all OpenBSD-specific, although the implementation discussed is, of course, OpenBSD.
You'll tend to see rewritten press releases in the business section. The front page of most newspapers originates in wire service articles: AP, Reuters, AFP, sometimes big national papers like the Washington Post or the New York Times.
If you click through a news story from a news aggregator like Google News, you'll note that many of them have identical text, because they're literally repeating the AP wire service story, crediting the original AP writer and all.
Actual reporters are used primarily for local news; very few newspapers have staff anywhere else. Most don't even have reporters in Washington, much less Paris/Jakarta/Darfur.
The bias comes not so much from the writers as from the editorial choices of which press releases and wire reports they're running and what page they put them on.
Either way, they rarely get the skeptical eye you'd really hope they get before receiving the imprimatur of being printed in the newspaper. Even a few phone calls would be nice.
It looks like most operating systems like relying on C. Wouldn't C# or Java require a VM and hence a little shakedown on the OS architecture? And wait, what would the VM be implemented with? There seems to be a strong case that a good hardware architecture can only be of help. The bad one, irrespective of what runs on top of it might always provide a source for trouble. Application developers have always tried to rely on a nice language + compiler + framework as they are evolving.
No Greater Friend, No Greater Enemy! (Lucius Cornelius Sulla)
True, C# and Java would need a VM. However there are traditional (non VM) languages which have build in buffer protection. Fortran was mentioned by another poster - I would add Ada to the list.
Unlike common believe they are suitable for low level system programming. They are also not old and outdated - both Ada and Fortran have current (not older then 10 years) ISO standards and will get a new ISO standarts soon.
The only problem is that the names are not common buzz words.
Martin
The Catholic Church counts some 1.1 billion members, give or take, so about the size of China, or perhaps a little less. Islam is the second-largest religion with about 850 million adherents, though this does not include sects such as Sunni and Shi'ite, which the Catholic Church basically is.
You can never go home again... but I guess you can shop there.
I would have said that the most obvious hardware-specific feature, that would protect against stack overflows, is Harvard architecture (vs. Von Neumann, present in almostall CPUs today).
In Harvard architecture, data and program memory are separate and separately accessed. This has a speedup benefit, as you can access the data in the same cycle you access the program memory, but the other advantage is, a stack overflow will not corrupt your program. For an example, the Atmel AVR risc microcontroller family uses Harvard architecture.
Sigged!
Sometimes you have to do that, but I prefer instead to make sure that all uses of that buffer don't assume it is zero-terminated unless I can guarantee that it is.
In another article on Slashdot today it's mentioned that Eric Raymond recommends Microsoft "open document formats" and "adhere to standards". Document formats aren't really an issue with Apple, but Apple is doing a very nice job of adhering to open standards these days. BSD Unix, Java, OpenGL, PDF, TCP/IP, X11...Apple is much more programmer friendly than it has ever been. The G5 machines are also very competitive on performance.
If you need access to commercial applications, or would rather spend money instead of time to accomplish your computing tasks, Mac makes a lot of sense compared with Linux. Windows, for me, is a distant third due to the time lost dealing with security issues, and a general distaste for programming something that inelegant. Besides, I can target Windows using Java with very little pain.
Just my $.02.
Galileo: "The Earth revolves around the Sun!"
Score: -1 100% Flamebait
Oh, yeah? Try getting data from an Oracle database in FORTRAN. They used to have something called, IIRC, pro*fortran, but no more. It took me about six months of interaction with people deeper and deeper in the Oracle organization to find out that that product is "deprecated" and no longer supported. Have you ever tried porting a FORTRAN program from VAX/VMS to whatever modern environment you use? Or from a PDP-11? So here is one reason why FORTRAN is dead: important software companies no longer support it.
Another reason: try finding programmers who are experienced in it. Where I work they have a 20-year-old system entirely written in FORTRAN. In the last twelve months, three junior engineers have quit their jobs because an old dinosaur insists that they must keep doing everything in FORTRAN instead of calling the old functions from C programs. What's the point of having "FORTRAN" in your resume, if the job market for that skill is so restricted?
But these are practical reasons, you wanted technical reasons, I guess. So try this: how do you do string manipulations? Functions that are one-liners in C become two pages long in FORTRAN. Or how about dynamic memory allocation?
I have used FORTRAN a lot in the past. I have seen its long and slow agony. I have seen the countless different standards, the many people and organizations who have said, "sure, you can do that in FORTRAN, do it like this" and have come with a solution that's incompatible with everything else.
Maybe FORTRAN could have evolved differently, if it wasn't so much a "commercial" software. All companies did incompatible improvements to FORTRAN so their marketing people could say "ours is the best FORTRAN in the market". Endless forking while C evolved in a standardized way. Today, to link a VAX FORTRAN library with an Oracle-accessing FORTRAN program originally written in AIX, for instance, is so hard that the easiest solution is to rewrite everything in C.
But I know people like you who believe FORTRAN is still the solution. As I mentioned, they are running through junior engineers at a fast rate. Luckily, that's not my department, here we do everything in either C/C++ or PHP.
Random offsets won't help much -- they'll help some, but what if you can write a LOT of data into that buffer? Give it a LARGE NOP sled.
Detect when a process is doing a lot of NOPs in a row and kill it? Ok. Use "AIAIAIAIAIAIAIAI..." 'A' = 0x41 = inc %ecx, 'I' = 0x49 = dec %ecx. Together, they are an effective NOP. Hell, most of the time, "AAAAAAAAA..." is an effective NOP. Does an attacker really care what's in ECX?
The problem is NOT the architecture, NOT the OS, and NOT the language. It's not a problem with libc, stdio, strcpy, or anything else. If you haven't figured this out by now, you might want to read about computer architecture -- computers do what you tell them to. I can write secure code in which I strcpy() from untrusted data into a static buffer on the stack, on an x86 running Windows with no NX. Hell, I'll even do it in real mode.
I'm not a DJB fanboy, but he does have quite a few good points. Programmers are lazy. Write secure code.
I mod down pyramid schemes in sigs.
Sunni and Shi'ite sects make up the significant majority of Muslims, but there are other sects. I know of the Druze, Alawi, and Ismali (Ismaeli?), but there are others, though even combined they are a very small percentage of the overall religion.
You can never go home again... but I guess you can shop there.