Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Make Ubuntu packages 90% faster by rebuilding them

gist.github.com

Post reply on HN
Print view View original

371–375 of 375 posts

Re: Make Ubuntu packages 90% faster by rebuilding them

#371

Post by worthless-trash »

ryao wrote: post #356
worthless-trash wrote: post #353

Earlier quoted context omitted.

The 'attack' there does require you to be able to run code and test within a single process with a single randomized address space, which is the exact vector that the web browser provides. Most times in C, each fork() (rather than thread) has a differential address space, so it's actually less severe than you think.

The kernel address space is the same regardless of how many fork() calls have been done. I would assume the exploitation path for a worst case scenario would be involve chaining exploits to do: AnC on userspace, JavaScript engine injection to native code, sandbox escape, AnC on kernel space, kernel native code injection. That would give complete control over a user’s machine just by having the user visit a web page.…

Its been a few days and a thousand kilometers since I've read the paper, I thought it referenced userspace. How is it able to infer kernel addresses that are not mapped in that process ?

Re: Make Ubuntu packages 90% faster by rebuilding them

#372

Post by jeffbee »

trod1234 wrote: post #366

Isn't it against the rules to post a link like this where the content is walled behind needing an account to access? I know most of us have accounts here, but when we're seeing something we want to read its not conducive to have to have to deal with roadblocks before we can see what is being talked about. Same goes for paywalls.

In what way does this require an account? It loads fine for me in a Chrome Incognito window.

Re: Make Ubuntu packages 90% faster by rebuilding them

#373

Post by trod1234 »

jeffbee wrote: post #372
trod1234 wrote: post #366

Isn't it against the rules to post a link like this where the content is walled behind needing an account to access? I know most of us have accounts here, but when we're seeing something we want to read its not conducive to have to have to deal with roadblocks before we can see what is being talked about. Same goes for paywalls.

In what way does this require an account? It loads fine for me in a Chrome Incognito window.

The link goes straight to a login page, doesn't let you see the page. On Firefox here.

Re: Make Ubuntu packages 90% faster by rebuilding them

#374

Post by ryao »

nickysielicki wrote: post #365
ryao wrote: post #358

Earlier quoted context omitted.

With attacks such as AnC, your logic fails. They can figure out the locations and get plenty of stable gadgets. Any shuffling of a deck of cards by Alice is pointless if Bob can inspect the deck after she shuffles them. It makes ASLR not very different from changing your sshd port. In both cases, this describes the security: https://web.archive.org/web/20240123122515if_/https://www.sy...

okay, sure, ASLR can be defeated by hardware leaks. The first rowhammer papers were over ten years ago, it's very old news. It's totally irrelevant to this thread. The fact that there exist designs that have hardware flaws which make them incapable of hosting a secure PRNG does not have any relevance to a discussion about the merits or lack thereof of a PRNG-based security measures. The systems you're referring to do…

> ASLR is not security through obscurity.

I used to think this, but hearing about the AnC attack changed my mind. I have never heard of anyone claiming to mitigate it.

Post reply on HN