Hacker Defeats Hardware-based Rootkit Detection

Manequintet writes "Joanna Rutkowska's latest bit of rootkit-related research shatters the myth that hardware-based (PCI cards or FireWire bus) RAM acquisition is the most reliable and secure way to do forensics. At this year's Black Hat Federal conference, she demonstrated three different attacks against AMD64 based systems, showing how the image of volatile memory (RAM) can be made different from the real contents of the physical memory as seen by the CPU. The overall problem, Rutkowska explained, is the design of the system that makes it impossible to reliably read memory from computers. "Maybe we should rethink the design of our computer systems so they they are somehow verifiable," she said."

I thought this was invalid anyway

I was under the impression that the only way to reliably detect a root-kit is to examine the system from another clean system?

ie remove the drive/devices and check them all.

Re:I thought this was invalid anyway

The rootkits that are written to the disk aren't the biggest problem. Like you said, one can "simply" look at the drive from a clean system. The problem is with rootkits that are only installed in RAM, while the system is running. The attacker exploits some hole in an application or in the OS and then transfers the whole system into a virtual machine that looks exactly like the real thing, so the rootkit can't be detected from inside the OS. Nothing is written to disk, so when the system is powered down, the rootkit vanishes into thin air. Servers are unlikely to be powered down often and even if they are, the cracker can simply attack again. With the rootkit undetected, it is likely that the exploited bug has not been corrected. Common wisdom was that this type of attack can be detected by looking at the contents of the RAM in a way which bypasses the OS. The rootkit has to be somewhere, right? Well, according to this article, there is a way to hide the real RAM contents from hardware assisted forensic methods.

Re:I thought this was invalid anyway

An "ultrathin hypervisor" as some call it is a very tiny OS wrapper. The wrapper does indeed have negligible effect on the system - about as much effect as, say, running a small background process.

Like I said, if you are going to do nothing, then sure, you'll have a hard time detecting it. But if it does something, like keylogging or sending spam, then it'll have measurable effects.

Wrong -- "measurable" in this sense may not be so measurable. The clever malware could fool the system timer to be a little bit off (say, 0.1%), so that it hides its tiny footprint in the timer. Thus, any attempt to query the timer would just return the expected result.

Not wrong. My timer is on my wrist. There's another one on the wall. Neither one is attached to my computer. There is another on my network for the specific purpose of keeping track of the slew in my various systems' clocks. Additionally if you start screwing with my system clock, other systems on my network would see this behavior in fucked up timings in the local system's network stack. If your hypothetical malware is slowing my system timer to hide its consumption of system resources, then keepalives would be arriving at remote hosts late. Also there would be drift in the system clock vs. my gps receiver.

Then there are devices that have physical clock rates. Serial ports, PS/2 ports, sound cards, video cards, etc. You can go into a tight loop for X number of intervals of playing a known number of 44.1 Khz samples to your sound card. If you used to be able to get through 250 million interations of the loop and now you can get through 247 million iterations of the loop, then you know something is consuming resources on your system. And if you really want to measure the impact of the malware then make your loop perform privileged operations so that they must be virtualized.

And there is the fact that you could compare two clocks, the mobo's time of day clock and the CPU's cycle clock. If you screw with them both you'll see all sorts of bad behaviors. If you don't, then you can compare the relative speed of the two to see the loss due to malware.

Finally the malware has to live somewhere in system RAM. It can't allow itself to be over written. The original OS knows how much RAM is supposed to be there, so just consume all memory. When it attempts to swap out to a local hard drive, go ahead and fill that up too.

There's a lot of hyperbole and sensationalism about virtualized root-kits.

Re:I thought this was invalid anyway

Issues:
The CPU is idle. A lot. The rootkit could quite easily only run itself when the CPU would otherwise be in nops or a delay loop. It's essentially impossible to use 100% of the CPU, because something, somewhere in a modern OS is generally going to run a few nops or go into a known loop state, at which the malware could just overwrite the nops or delay instructions and not delay the system at all. So your method isn't terribly great.
Now, calling privileged instructions as you mention is a brilliant way of sensing the malware, as it's unavoidable that the malware must handle most privleged instructions acting as a virtual machine, and then it'd definitely be losing clock cycles.
Unless you're listening to the samples and counting every one the rootkit could just discard enough of the calls to make the clock rate appear the same.
The OS has no idea if the virtual machine is swapping for it. And unless you're filling the RAM with random data and then reading it back + timing it memtest86 style, the VM could just discard all the memory you allocate.

Yes, there is a ton of hyperbole and sensationalism. Virtualized rootkits are among the least common threats currently on the internet and all users and 99% of admins need not worry about them, as they have much more important things to be concerned about. But for the .001% of admins who run with highly sensitive data and audit every line of code going into their systems, this is a definite threat that they should be concerned about detecting. And they're pretty difficult to detect. And they're something new and special, so they're the Next Big Thing.

TWSS

"Maybe we should rethink the design of our computer systems so they they are somehow verifiable," she said.

that's what she said!

well

If sony could rootkit your computer and your hardware couldnt tell, would they?

she shatters two myths really ...

1) that hardware based rootkit detection is unreliable and
2) that a beautiful girl cannot be a part of the geeky world of cyber security research (considered exclusively a part of male fiefdom).

DRM

"Maybe we should rethink the design of our computer systems so they they are somehow verifiable," she said."

Yay, DRM in every piece of hardware to the rescue!

Re:DRM

Yay, DRM in every piece of hardware to the rescue!

Sounds actually like the exact opposite. DRM tries to hide away things, while this would give devices the ability to see everything that goes on inside the system RAM.

AACS "Improvement"

At this year's Black Hat Federal conference, she demonstrated three different attacks against AMD64 based systems, showing how the image of volatile memory (RAM) can be made different from the real contents of the physical memory as seen by the CPU.

Isn't this exactly what HD-DVD / Blu-Ray players need to prevent the AACS keys from being stolen? Just last week there was a story saying something like "PC-based movie players are inherently crackable, because the key has to be in main system memory for at least a brief instance, and then we can copy it." Now, this lady says there are methods to prevent anyone from truly reading what is in RAM. I don't understand.

Re:AACS "Improvement"

Well, no. Not entirely.

Under normal conditions, that's correct. If a player has loaded the key into memory somewhere in order to use it, you can probably isolate the location in memory and retrieve the key. Which is what has been done to retrieve the AACS keys.

But the pathological case, the case dealing with rootkits, changes the game. How do you track the contents of your physical memory? Typically, through OS mechanisms. What happens if a rootkit (or a software media player using rootkit technology) subverts the OS mechanisms? You can't be assured of reliably tracking the contents of memory any more; maybe your OS is LYING to you! What is really in memory is not what you're being told is in memory, and maybe you can't find that key any longer.

Which brings us back to the article. Direct Memory Access (DMA) is a way of taking the responsibility for managing physical memory access (reading, writing, whatever) away from the processor and moving it to some other place in hardware (presumably some place that you can trust). And that's what hardware-based rootkit detection is about. Use hardware with DMA (which you trust) to access memory instead of letting the processor do the work and relying on the OS to tell you the truth.

The problem is that the way computers are currently designed, there's no way of starting DMA without having to talk to the processor (by way of the OS) first. Your DMA hardware has to ask "Hey, can I access memory?" and the OS has to say "Sure thing! You do it, and we won't bother the processor any more!"

But if the (subverted-by-a-rootkit) OS has a vested interest in you NOT being able to get true results using DMA, well, what are you going to do? The OS will just interfere. That's why Rutkowska is suggesting a direct, non-subvertable hardware port that you can jack into to use DMA without having to go through the OS first.

Trying to have her cake and eat it too?

Let's see ... last year, she got all over the headlines claiming that virtual machines are a Bad Idea because rootkits could use them to remain undetectable (even though virtual machine experts [blogspot.com] discounted her "trivially easy and left unimplemented" parts as technically intractable).

And now a year later, she claims we need specialized hardware interfaces to scan memory for rootkits, even though this problem is laughably easy in the world of virtual machines.

And on to the actual work [com.com] ... the research basically observes that MTTR registers (some of the MSRs in the CPU) can cause memory mappings to look different between the CPU and the northbridge, and then comes up with a pretty easy way to cause the northbridge to either lock up or read data that is different (really easy once you see the specs for the appropriate registers). And she totally ignores the possibility of a system defending itself against this attack by verifying the registers she's modifying. Lousy research, girl.

Oddly enough, this "hack" is ALREADY IN USE ON YOUR SYSTEM and is actually necessary. See, when the processor is running in SMM (System Management Mode), it switches to exactly this configuration: the PCI bus sees VGA hardware mapped at the well-known address, but the processor maps the RAM at that address, which gives SMM mode a few kilobytes of memory that the normal system can't touch. SMM mode is used for things like "legacy USB devices" (e.g. having your USB keyboard act like PS/2 so DOS can use it) and other implement-in-software hacks that your OS doesn't know about, but your BIOS vendor gives you as "value-added features".

She's a girl

and reasonably cute, blah blah basement blah blah over 30 blah blah imaginary blah blah

good luck...

The MPAA/RIAA would just *love* it if there was a port on your motherboard you could just plug something into and get direct access to the contents of RAM, bypassing OS completely.

There's already one solution available

"I'm thinking about motherboard manufacturers adding a special port which would allow for *direct* (this time really "direct") access to RAM and potentially some other critical resources like e.g. CPU system registers and maybe even caches," she said.

You can already do this, with many common CPUs. It's called JTAG. In short, it allows you to control the CPU directly, so that you can do exactly what Ms. Rutkowska proposes. That includes by-passing the caches and getting direct access to memory.

JTAG is what embedded people use to port an O.S. to a new hardware platform. And to debug really tough kernel problems. It beats the snot out of printks anyday. And there are certain sections of boot-code and kernel code where it is extremely difficult and annoying to develop without JTAG.

There are two immediate problems with JTAG however. The first is that not all CPUs support it. Believe it or not, I've met CPU designers who have never heard of JTAG (and this is usually a clue that they don't know what the heck they are doing).

The second problem is that some CPU manufacturers consider the JTAG interface proprietary. Intel is one (there's only one JTAG debugger available for x86, and it will cost you between $5,000 - 15,000 depending on what you get). That is absolutely silly, as these can be built for well under $500.

Why they keep the JTAG API interface proprietary is beyond me. I have yet to hear a non-lame excuse yet.

But in any case, the point is that this problem has already been solved. It's surprising to me that anyone seriously doing forensics wouldn't be using JTAG already, for the reasons that Ms. Rutkowska suggests.

FireWire access can also be redirected

The slide set mentions accessing memory via FireWire, but doesn't say much about it. FireWire understands packets for "reading and writing memory", along with ordinary data packets. But whether memory access packets actually read and write physical memory is up to the driver, when it configures the FireWire controller. The driver can set controller registers so that the physical address range accessible from the hardware controller is limited. Other addresses just pass the packets to the driver.

So it should be straightforward to make a FireWire port return whatever contents of memory the attacker wants to display. Especially since, on PCs, that function isn't otherwise used for much.

In fact, for security, a PC shouldn't accept FireWire memory read and write packets at the hardware level. (Does Windows? I know that QNX does not, having written a FireWire driver for it, and I don't think Linux does, but I'm not sure.) There's nothing that talks to a PC that needs that feature. It's used mostly for talking to "device registers" in peripherals (where, typically, the "device register" is implemented as a switch statement in firmware.) For example, you turn on and set up a FireWire camera by sending packets that write to "device registers". But the images from the camera come back as FireWire data packets, processed by software. They are not "external DMA transfers." You can only read or write one 32-bit word per "memory access" packet anyway, so it's a very inefficient way to move data. All sizable FireWire data is sent in longer packets processed by software.

(FireWire is really a LAN, not a bus. FireWire controllers work a lot like Ethernet controllers, with buffer rings for input and output, although Ethernet uses collision detection and FireWire uses an arbitrarily-chosen master node to schedule the wire. It's not at all like the PCI bus.)

Seems like some useful service being provided...

Seems like the Rutkowska paper a) exposes PCI cards used as memory verifiers as unreliable in off-the-shelf hardware--the PCI memory verifier products cited in the paper (one is from BBN no less) might not have been properly reviewed, and might be in use in US DOD computing systems b) sheds some light on how COTS hardware _could_ be less vulnerable to rootkit manipulation, if customers demand it--not unreasonable.

security must be designed into hardware

Without consideration of the problem at the time all of the system hardware is designed, there is no secure solution. This is in fact a very complex problem.

For instance, most CPUs and complex driver chips include undocumented registers, which can be used to hide code or data from analysis. Some of these register areas can be quite large. The common solutions almost invariably rely on security through obscurity, since the internal design of chips is not widely available. How can one clear or verify memory if the total amount of memory is unknown? An attacker need merely relocate himself dynamically to avoid detection.

The two most common attempts at better security involve two approaches: additional hardware which requires special keys for access (such as is used in some DRM systems), and secondary or even tertiary computers to monitor the primary system. There are even systems with back-to-back PCI bridges, where the second PCI bridge on a completely separate computer audits the behaviour of the first PCI bridge. All software is considered "hostile" in systems which are serious about security.

Even the available security features often are not enabled or used, because of poor design. For example, some video decoding chips have read only register to store keys for DRM purposes, but many STBs don't use them because the designs are flawed, or because the use of the features incurs unacceptable manufacturing and deployment costs. Similarly, JTAG access often is not locked, because the manufacturers prefer the ability to field diagnosis easily, and assume that most attackers won't be able to figure out how to break into the unlocked systems. Even worse, these advanced features are not used because the most egregious holes are even easier to exploit, so why bother to harden the front door when the windows and back door remain open?

Unfortunately, most of the "secure" systems are lame, done without adequate design review. Much common hardware from cable boxes to military equipment is full of holes. The failures remain latent only because of NDAs, government security classification, and other factors impeding review.

No, you can't build a secure system without secure hadware, and you can't verify the contents of memory without special hardware support.

Call me confused ....

Keep in mind I'm actually an Ex HW_Hack ........ From Wikipedia:

A rootkit is a set of software tools intended to conceal running processes, files or system data from the operating system. Rootkits have their origin in relatively benign applications, but in recent years have been used increasingly by malware to help intruders maintain access to systems while avoiding detection. Rootkits exist for a variety of operating systems, such as Linux, Solaris and versions of Microsoft Windows. Rootkits often modify parts of the operating system or install themselves as drivers or kernel modules.

The best and most reliable method for rootkit detection is to shut down the computer suspected of infection and check its storage by booting from an alternative media (e.g. rescue CD-ROM or USB flash drive). A non-running rootkit cannot hide its presence and most established antivirus programs will identify rootkits armed via standard OS calls (which are supposedly doctored by the rootkit) and lower level queries, which ought to remain reliable. If there is a difference the presence of a rootkit infection can be assumed. Rootkits attempt to protect themselves by monitoring running processes and suspending their activity until the scanning has finished.

So .... with disk space becoming trivial couldn't your OS make a copy of itself to a locked partition during OS install - these become master reference files. Then a second security CPU (Xscale etc.) is embedded on the MB with access to system memory (dual-port) ---- during idle periods the security CPU runs random OS calls on system memory and compares those to results of system call from the locked partition.

As I ejected from Intel R+D in '04 we were already doing early work on embeddng Xscale on MBs for other purposes ........ beats me I'm just a ex-hw-hack

Your Philosophies

Joanna Rutkowska's research is catching up to a truth few realized until just recently, This is just the tip of a whole can of worms that has been wiggling right under our noses for years.

If you check the comments below, (to a very good article) some commenters are rather hysterical, (in a bad way) and for good reason, but reflect the truth.

Rootkits headed for BIOS
Comments:

http://www.securityfocus.com/cgi-bin/index.cgi?c=a rticlecomments&op=display_comments&ArticleID=11372 &expand_all=true&mode=threaded [securityfocus.com]

After reading this, if you don't have experience in these matters please refrain from commenting.
Rather, go read more of what Ms. Rutkowska has so expertly revealed:

http://invisiblethings.org/papers.html [invisiblethings.org]

"There are more things in heaven and earth , Haratio, than are dreamt of in your philosophies."

It's a man baby! It's a man!

http://www.rutkowska.yoyo.pl/ [rutkowska.yoyo.pl]

"Until July 2003, a computer security researcher Jan Krzysztof Rutkowski used his school-provided e-mail account at Warsaw University of Technology ([e-mail]) to publish various security materials on Windows kernel rootkit hiding and detection...This person had ceased all public security research mid-2003.

Within less than two months, a previously unknown researcher named Joanna Rutkowska began to publish papers on Windows rootkit detection and hiding techniques (Concepts for the Stealth Windows Rootkit, first paper by Joanna Rutkowska) that were very closely related to earlier contributions by Jan and extended some of his ideas, referencing previous work (e.g., Detecting Windows Server Compromises with Patchfinder 2).

I love articles like this, they crush wannabes

I worked for Guardent for a while, and their coders were the elitist of the elite, if you listened to them. Then you read something like this to show what yutzes they were.

Deja vu...

[Neo sees a black cat walk by them, and then a similar black cat walk by them just like the first one]
Neo: Whoa. Déjà vu.
[Everyone freezes right in their tracks]
Trinity: What did you just say?
Neo: Nothing. Just had a little déjà vu.
Trinity: What did you see?
Cypher: What happened?
Neo: A black cat went past us, and then another that looked just like it.
Trinity: How much like it? Was it the same cat?
Neo: It might have been. I'm not sure.
Morpheus: Switch! Apoc!
Neo: What is it?
Trinity: A déjà vu is usually a glitch in the Matrix. It happens when they change something.

reality check

Just when the good guys think they got it right, the bad guy gives a smug and says, "really?" Sometimes we forget that the main motives for hackers to hack are challenge, fame, ideology, and sometimes money...

Re:Why does this chick get so much press on Slashd

To be honest though, the sharp knees ruin it for me.

Plus when you think about it, sperm is the ultimate malware.