Winners of Google Capture-The-Flag Finals 2019 🏳️

it's now sunday in the morning 8 15 or so i'm just getting ready and then i head to the google office again for the second day and the last day of the ctf [Music] what's that i mean so we are getting our second attempt at the bomb challenge we are ready why does google have this 10 is missing okay 10 is 10 is the output of q5 yeah 2 2 q5 okay do you know about the riddle challenge no um do you know what riddle the no so riddle is one of the one of the cpu bugs in riddle is one of intel only i think um and was part way public like half a year ago and nobody ever released a pog for this like it's there's no no public pockets visor now i saw some ripple where they have a pork but it didn't work when i tried it um so i decided to make a challenge which is like here's code without a bark inside here's a link to the paper and the slides just implement that and leak the flag and were there any sauce here there were five solves after the first day so i think the first one was around after one or six hours so the best team took around six hours after release um we actually had to change one of the other challenges because we figured out the same exploit will work for this one as well so we had to like run it on a single core so that that is not affected but yeah cool that's it nice thank you i'm pedro i i was the technical leader of the crypto category and i also made one crypto challenge one crypto challenge what's the name of the crypto challenge fractalization okay so can you give us just like a gist of what the challenge is about okay uh it's an rsa challenge and the goal is to factorize on rsa models yeah in general that's the idea yeah and of course like i mean i'm aware of like the basic rsa kind of challenge where you know the the factorization is already yeah db or something no this is the cool part of the challenge because if you use general ctf tools or if you use some factory general factorization goal idioms or just try factor db you are not going to find anything but uh we d and we also didn't provide the source code of the key generator it was on purpose but actually the private key did their private key it was encrypted with aes ecb and people that are usual with crypto they know that yes ecb has a known venerable and no problem that if you encrypt like some plaintext using the same key and if you do that many times the result will always be the same so it can leave some patterns in this cipher text so this uh private the private key that i i provided the encrypt it encrypted it's it's possible to see that on this encrypted private key some patents in the aes ecb the private key contains the primes so people will know that the primes contain some repeat repetitively patterns so there are some uh latest based algorithms that can be used to factorize the the model is basically only on this information okay so the the private key is pretty large can't be factored with regular standard tools but the kind of like the search space is basically minimized because of uh there are repeating uh patterns that with asc you can see that the blocks are the same yeah yeah the same so uh i've studied computer science so i had some math background obviously but it's also already now a couple of years back so can you try you know it doesn't have to be school level math but also not the highest one i think how does this kind of algorithm kind of work or what other terms if somebody would want to look into how this algorithm works to a factor or something like this okay uh so basically based on this information okay so the one of the primes it has a repetitive bit patterns so you if you represent this prime as a fraction okay so some number uh some numerator divided by some denominator using some lattice based methods the result if you create a matrix the result will be actually a multiplier of this prime so now if you have a multiplier of this prime and you calculate the gcd between this multiplier and the modulus you'll get the prime so yeah basically this is the idea i know that some people can solve it using other methods like uh copy smith there are some things that you can do with copies mid but using this uh lattice method it i think it's a simple way to solve it so you don't find it in general uh ctf tools uh but in some academic papers you can find it actually this this algorithm was an idea of daniel bleschenbacher and i implemented it for a challenge for a ctf challenge he he also validated the challenge in the end is it oh okay is it deep liking behalf of the from yeah it's the same person okay so yeah that was my question okay he's also a googler apparently yeah yeah okay interesting for me always crypto was very hard because i do like math but i never kind of was able to get my head into it if if i think there are many people like me out there who kind of studied computer science had some like basic introductions in uh in kakos and all that stuff but but never if they would try again to learn a bit more of the advanced math and understand like these kind of papers to get into these kind of ctf channels do you have any recommendations regarding that uh play ctf and usually combine the ctf knowledge with academic knowledge because if you just play ctf you usually you you you are you focus too much only on the ctf problems but the people that that publish papers that do the actual academic work they have a lot of new things that they publish all the time new things new research so yeah i think combining those two things playing ctf plus doing some academic work academic research it's it's a good plan uh in terms of tooling like what does somebody that saw ctf cryptochallenges uh use is it like matlab like is that literally like the tools that these kind of tools that are being used the solution for this challenge we use it sage because it has some nice algorithms for solving ll reductions lattice reductions i usually use sage or yeah cool thank you so much for your time bringing the swag we're on level 8. i'm in the building google will it security do you think it's reliable 50 50. 50 50. okay we'll see all right three two one and we have a couch nice [Applause] now you can jump too i mean you can wake up yeah and it's a bee9 that's really cool mind-blowing it's legit i have nothing to say [Music] i got it okay now that all teams have completed the bomb challenge and we will deliver the flags to their teams which have solved the challenge successfully in the order of the least time of start thank you all my flags have now been delivered [Applause] he's ready to enter the flag if we see calc all right three two one how does it feel hey good game everyone thank you for playing and now we will do it like this basically uh i will pass the microphone to jim in a second who will say a few words then we'll do the ctf task presentations by intended solutions really quickly and then we will ask everyone to go upstairs so during the presentation feel free to pack your stuff because around seven we'll have to go upstairs for dinner and celebrations and awards ceremony as well so this challenge was about factorizing rsa models so actually we didn't provide the source code for how we generated the primes the rsa key but we provided the private key encrypted with aesc and it there is a very known problem with aes ecb that it maintains the bit patterns if the inputs are the same if the plaintext and the key remains the same so analyzing the encrypted private key you could see the bit buttons there it was in one of the primes so using some triple l reduced algorithms lattice reduces algorithms you could actually for example represent p as a fraction like as a fraction like this and after solving the the matrix like this using triple l you actually would get some valid that is a multiplayer of one of the primes so basically just calculate calculating the gcd of this number that you get and the the modulus you get the the prime so that's it then you can just do the usual rac steps nice thank you [Music] those of you who are new to escalate we had three parallel events running we had the ctf finals which 10 teams participated in we had the bug swap program which is for our top vulnerability hunters in google products and we had energy which was a student event where they came and learned and watched all those wonderful things that you guys were up to with that being said i'd like to invite ginval caldwin to the stage to announce the winners of the ctf 2019. okay so uh before we announce the owners and the top three uh as you as some of you know there has been some miss well a problem with uh flag submission not really finishing at the time we said it's finished actually there was one more team but which submitted a flag later on and we didn't notice until uh like half an hour ago so you might find a typo on some of the tracks but we have corrected everything and everything is according to the rules now perfect so with that great introduction third place spam and hex congratulations and spam and hacks got 1950 points the first place with 3 350 points but you all know who it is it's based on the winners of google ctf 2019 perfect so five pc second place congratulations it's gadget overflow g'day mate how's it going how's the subscriber count going not so well as is for you don't worry you'll get there thank you so much subscribe to gadget overflow so yesterday was the last day of the ctf and we got a second chance at the bomb unfortunately also failed but in the end uh only one ctf team solved the challenge but also one vrp team so from the back bounty hunters uh they also got a chance and they and they solved it so that's pretty impressive right after the ctf the authors of the challenges so the googlers would come up to stage and explain their solutions to the challenges and i think that is really really awesome because as a ctf player you wonder what the solutions are and it is fun after the ctf to go to other teams and ask around but you can still do that and you just get a quick overview what the solution was and i think that is so great and it's so helpful and adds to it i think afterwards we had to quickly pack up and then head upstairs to a different floor where there was kind of like an after party uh we got some food there were drinks and they also did the awards ceremony there so yeah the first three places got some some money at the first place got to hold the trophy and also the buck hunters got also some gear they were drawn out of a head and they could select some some of the stuff yeah and there i had just awesome conversations with a lot of different people from other ctf teams i've never met before i talked to some of the students from energy yeah so it was a it was just really fun then of course offices have to get shut down at some point so we got kicked out of the google office at some point then i went with some of them into a pub near the hotel and mostly those were vrp people so back hunters and so had more awesome conversations with those it's so interesting their perspective on security and google products and basically all of them were saying there's nothing special about it it just requires some time and also people are scared of it to look at google for bugs because they think that they can't find anything but that's the only reason why they can still find stuff because people are too scared to do it like me i'm too scared to find stuff on google and so i'm the kind of person i'm the reason why they are still finding bugs because uh they are the only ones doing it if you had some concerns if you should try it i think you should try it i mean that's basically what all of them said you just need to do it and i know it takes time and a lot of effort and stuff but persistency discipline that's basically all it is after the pub we went to a fast food restaurant and grabbed a quick bite and then we went back to the hotel where we met a couple of other people uh some of the ctf players this is where redford released the first ever public poc of uh riddle exploit it was kind of funny because it was kind of pressured into releasing it and he had to replace a lot of variable names because uh he originally used corva and he had to replace it to make it you know fine for the public release so i stayed there for a bit but got really tired so i think i went to my hotel room at like 3 a.m 3 30 a.m around that time and so i i went straight to bed and now i'm awake need to quickly pack and then my flight leaves at like 4 p.m so i have plenty of time i will just sit around in the lobby maybe walk around a little bit or so so i hope you really enjoyed this whole journey let me know what you think about it what did you think about the event how does how did that look like any feedback for google to make it better and any feedback for me to make videos like this better it's the first time i tried to use such a fancy camera so i'm sorry for all the blurry footage or all the wrongly exposed footage i think in overall i am still pretty happy with the result [Music] you

Channel: LiveOverflow

Views: 49,936

Rating: 4.9622245 out of 5

Keywords: Live Overflow, liveoverflow, hacking tutorial, how to hack, exploit tutorial, ctf, capture the flag, google ctf, dragon sector, p4, pasten, gynvael, crypto

Id: T1lP1b89_cc

Length: 20min 54sec (1254 seconds)

Published: Fri Aug 21 2020