This morning I had a course on Return Oriented Programming given by Jonathan Salwan, a classmate of mine also famous inventor of RopGadget.
The slides are here.
A lot of interesting things there. Apparently it's still kind of impossible to completely protect your C code against that kind of attack. Even with all the ASLR, PIE, NX bit and other protections... There is also an awesome lecture about ROP on Coursera I linked to in the previous post here.
Basically, since you can't execute code in the stack, and since the addresses of libraries are randomized because of ASLR, you can find bits of codes ending with a return (called gadgets) and chain them since you control the stack (thus the saved EIPs). What I learned by doing was that it gets complicated if it's 64bits (since a lot of address will have a lot of 0x00 and you can't point to those doing a buffer overflow through a strcpy or something similar) and you won't get a lot of those gadgets if you have dynamically loaded libraries. Static libraries are loaded in the .text section (which is executable of course), so that's all good. Also a good way to store strings of data are in the .data section since it is untouched by the randomization contrarily to the stack.
A lot of researches is done on the subject and new tools like RopGadget are coming, using an old concept (but still actively researched): the SAT solvers. There seems to be a problem though, those SAT solvers yield a set of gadgets to be used for some action you want to accomplish with your shellcode, but you have to do the work of putting them in the right order.
This is what I took from that talk, you can question the guy if that interests you!
I've already talked about Coursera before, and how much I liked it.
The Cryptography course by Dan Boneh is amazing and I often come back to it when I need a reminder. For example, even today I rewatched his video on AES because I was studying Differential Fault Analysis on AES (which is changing bits of the state during one round of AES to leak information about the last round subkey).
So if I could give you another course recommendation, it would be Software Security by Michael Hicks. It looks ultra complete and the few videos I've watched (to complete the security course I'm taking at the University of Bordeaux by Emmanuel Fleury) are top notch.
Communication Theory of Secrecy Systems is a paper published in 1949 by Claude Shannon discussing cryptography from the viewpoint of information theory. It is one of the foundational treatments (arguably the foundational treatment) of modern cryptography. It is also a proof that all theoretically unbreakable ciphers must have the same requirements as the one-time pad.
source: wikipedia
Crypt, already omitted by most linux distributions, is being retired as well by OpenBSD: http://www.tedunangst.com/flak/post/retiring-crypt
The crypt function is a unix classic. Unfortunately, its age is showing. It’s an interface from another time, out of place on modern systems, and it’s time for OpenBSD to move on.
I found an old Matthew Green's post where he wrote a really useful list of cryptography blogs and resources
I'll get back here after reading everything.
Studying about smartcard there seem to be a lot about whitboxes to learn, since it is indeed a whitebox: the encryption/decryption that are done inside the cards can be analyzed since you own the card. Analysis are separated in different categories like non-intrusive and intrusive. Intrusive because for efficient analysis you would have to remove some part of the plastic covering the interesting parts and directly plug yourself on the chip. This is what Differential Power Analysis (DPA) do, it's a stronger kind of Simple Power Analaysis (SPA).
Kocher & al found out about this in 1998 and released a paper that is still very useful today: http://www.cryptography.com/public/pdf/DPA.pdf
The idea is to record the power consumption of the chip along multiple encryptions. You then obtain curves with pics that you can correlate to XORs operations being performed. You can guess what cipher is used, and where are the known rounds/operations of the cipher from the intensities of some peaks, and the periodicity of some patterns. In the paper they study DES which is still the state of the art for block ciphers then.
Looking at a big number of such curves, along with the messages (or ciphertexts) they encrypted, you can focus on one operation and one bit of the internal state to find out one bit of one of the subkey. One bit should affect the number of XORs being performed thus you should find a correlation between the bit you're looking for and the power consumption at one point. Repeat and find all the other ones. It's powerful because you only need to find one bit of the subkey, one after the other.
It's pretty hard to explain it without pictures (and a video would be even better, that's always something I have been wanting to do, if I dig deeper into it maybe I'll try that). But the basic idea is here, if you want more info check the original paper
It was already pretty amazing when Cloudflare introduced Universal SSL (and this blog uses cloudflare ssl by the way).
Today the EFF has launched Let's Encrypt that aims to simplify the setup of SSL. They claim it takes 20-30 seconds to deploy SSL to your server. And this for free.
I was reading some articles on the security blog of stackexchange. Ended up there reading articles/comments from Thomas Pornin who is one of the best answerer on stackoverflow.
I ran into this one intitled Is our entire password strategy flawed?
I wanted to bring my point of view on how to deal with multiple passwords. I don't necessarily do this because it's not practical but I'm trying more and more.
So if I were to be extremely paranoiac I would:
- use a password manager like 1Password for websites you don’t really care.
- use passwords you memorise for websites you care about.
- use multi-factor authentification for critical websites.
1. Password Manager
I've never used 1Password but it seems to generate passwords on the fly when you need to sign up on a new website. It's pretty cool! But a problem arises when you need to login on some website when you're not using your computer. If you don't know the passwords it created then you will always be dependent of this password manager.
2. Memorise
A good idea would be to hash the name of the website + some salt only you know, and use it as a password. All of that in your head. That's what one of the famous Blum proposes. More here. He appeared to have invented a hash you could compute mentally.
3. Two-Factor Authentification
I really like the yubikey (and own one). It's literally a secret key. Every time I need to log into gmail from a cybercafe I wish I had it configured with my yubikey.
Bonus
By the way, if you're scared there might be a keylogger but really have to enter some password you could prey on the fact that the keylogger is badly coded and, when entering your password, could move to another input field and write random words, then come back to the password input field and type some more letters of your password, etc.. .
Last year I also learned how to read dotsies (I completely forgot how to read it now though...) and I seldom switched all the fonts to dotsies so no one could look over my shoulder and read what I was reading/typing.
