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Unikernels are secure

unikernel.org

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Re: Unikernels are secure

#11

Post by digi_owl »

Cieplak wrote: post #5

Hypothetically, if there were a buffer overflow in a unikernel process, wouldn't it potentially give the exploit full-system access, whereas a normal operating system would detect the out-of-bounds memory access and kill the process? I'm sorry if this is an ignorant question.

Best i can tell, unikernels are a reaction to the shift from VMs to containers in cloud services. This by pairing down the content of a VM to the bare minimum.

Meaning that if you have a buffer overflow or similar, all you could access was what was in the VM (unless you also happen to pack a VM escape).

That said, i can't help think "DOS in a can" whenever i read about unikernels.

Re: Unikernels are secure

#12

Post by meson2k »

> Good luck guessing that address. Our own unikernel, IncludeOS, randomizes addresses at each build, so even with access to source code you still don’t know the memory layout.

"There is one mortal sin in computer security (or by the way, in any kind of security) that is feeling safe. It’s just a variation of pride to be true, but it’s very deadly. Blindly trusting a protection technology is an extreme error."

Read up on DEP. Randomizing function addresses at each build is useless when it comes to attack mitigation. You need to randomize addresses at each execution.

Re: Unikernels are secure

#13

Post by dreamdu5t »

Hard to take claims of security seriously for untyped languages which are not provably correct and lack a denotational semantics. Let's start by provably not compiling buffer overflows and memory overreads considering those are the vast majority of RCE and privilege escalation.

Re: Unikernels are secure

#14

Post by leggomylibro »

Cieplak wrote: post #5

Hypothetically, if there were a buffer overflow in a unikernel process, wouldn't it potentially give the exploit full-system access, whereas a normal operating system would detect the out-of-bounds memory access and kill the process? I'm sorry if this is an ignorant question.

I could be wrong, but I think this is what Memory Management Units are for, on processor chips. It's one major differentiator between application processors and more embedded ones like Cortex-M or ATMega MCUs, which typically can't run complex modern operating systems. A lot of those chips have a simpler Memory Protection Unit that does basic enforcement of permissions like read+execute, read+write, etc, but they lack the ability to partition memory virtually between a large number of potential 'owners.'

I think - I'm still learning about this embedded stuff.

Re: Unikernels are secure

#16

Post by vertex-four »

FungalRaincloud wrote: post #10

I don't really like the argument that something is 'secure' because it is not vulnerable in the same ways that an alternative is. I think this is why I like talking about encryption so much. It's possible to mathematically prove the security of encryption algorithms, and all that's really left to pick apart is the implementation, politics and impact.

Ehh... you can often prove that X algorithm is not susceptible to A, B or C attacks, but you cannot usually prove that the algorithm is "secure" in a fundamental sense.

Re: Unikernels are secure

#17

Post by dreamdu5t »

adrianN wrote: post #8
rwmj wrote: post #4

It's secure if and only if there's a formal proof.

"Secure" sounds like a binary attribute but it's actually not. A formal proof doesn't save you from errors in the specification. At some point you need trust, the amount of trust needed is inversely proportional to the security.

Without a formal proof there is no measure of correctness at all.

Re: Unikernels are secure

#18

Post by vertex-four »

leggomylibro wrote: post #14
Cieplak wrote: post #5

Hypothetically, if there were a buffer overflow in a unikernel process, wouldn't it potentially give the exploit full-system access, whereas a normal operating system would detect the out-of-bounds memory access and kill the process? I'm sorry if this is an ignorant question.

I could be wrong, but I think this is what Memory Management Units are for, on processor chips. It's one major differentiator between application processors and more embedded ones like Cortex-M or ATMega MCUs, which typically can't run complex modern operating systems. A lot of those chips have a simpler Memory Protection Unit that does basic enforcement of permissions like read+execute, read+write, etc, but they lac…

The point is that once you're doing that, and implementing communication between all your separate owners (which map pretty precisely to a reasonable definition of "processes")... you've just implemented another operating system, not a unikernel.

Re: Unikernels are secure

#19

Post by eutectic »

FungalRaincloud wrote: post #10

I don't really like the argument that something is 'secure' because it is not vulnerable in the same ways that an alternative is. I think this is why I like talking about encryption so much. It's possible to mathematically prove the security of encryption algorithms, and all that's really left to pick apart is the implementation, politics and impact.

Even crypto algorithms rely on unproven assumptions for their security, even ignoring e.g. side-channel attacks.

Re: Unikernels are secure

#20

Post by throwaway91111 »

Cieplak wrote: post #5

Hypothetically, if there were a buffer overflow in a unikernel process, wouldn't it potentially give the exploit full-system access, whereas a normal operating system would detect the out-of-bounds memory access and kill the process? I'm sorry if this is an ignorant question.

Not necessarily. The kernel can run the code in non ring 0, ie in userspace. I can't speak to what is typical, but i imagine you'd get most of your gains by stripping most vulnerable code out of the system outright.
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