Date: Sat, 6 Jul 2013 13:24:58 +0400 From: Aleksey Cherepanov <aleksey.4erepanov@...il.com> To: john-users@...ts.openwall.com Subject: team john-users write-up for PHDays Hash Runner 2013 contest Write-up for PHDays Hash Runner 2013 Resources summary Active Members: 15 Names: Aleksey Cherepanov, Alexander Cherepanov, Dhiru Kholia, elijah[w&p], Frank, guth, Jose Luis Herrera, Matt Weir, Agap1, sftp, Solar, tab, ukasz, vn, Vasily Kulikov a.k.a. segoon. Software: John the Ripper (with various patches), custom scripts. Hardware: ~8 gpus, ~150 cpu cores at most Preface The contest was fun and challenging, it helped us test some experimental John the Ripper code and identify areas for further improvement. We'd like to thank Positive Technologies for organizing the event. We would also like to thank all other teams who participated and made it tough for us to compete. ;-) Resources We got 4 new team members and we hope they'll stay with us. You could join us too! In addition to the active members listed above, community members with too little time for participation helped us with preparations before the contest and provided us helpful advice during the contest. We hope they'll have more time to participate next time. We used bleeding-jumbo version of John the Ripper right from our public repository, and custom scripts. I guess we had about 8 gpus and at most 150 cpu cores. Not all of these powers were used or even accessible during both days. Some members used just one computer or even a laptop. Contest The contest started with a registration. It was not clear how to register our existing account for Hash Runner so I registered a new account. It was not hard but the lack of information added stress. The lack of information was the only major problem of this contest and annoyed us many times. BTW I think smaller teams suffer much more from the lack of information than bigger teams. Though the organizers were very friendly and answered all questions. The end of the contest was smooth and we were totally in cracking. The beginning was not smooth for us because delayed start broke our plans (some guys had to go to jobs). I spent a lot of time converting hashes to canonical form. Though team members already started cracking. Dhiru Kholia made a format for sha3-256 (keccak-256) in 10 minutes. It was amazing! Keccak provided us with noticeable amount of points in the end. BTW keccak format was pushed into our public repository as soon as it was created so any team was able to use it. Also Dhiru Kholia made a format for md5-broken that was used during the whole contest. He did this format in a short time too. Nevertheless I did an alternative implementation being based on different principle. Then Alexander Cherepanov added support to merge results from these two implementations. So we had two fully featured implementations of md5-broken. Both of them were used actively. The alternative implementation allowed Solar to effortlessly use experimental code for password generation on GPU (a.k.a. PG-test) made by myrice (Dongdong Li) during GSoC 2012. Though we spent more time on alternative implementation of md5-broken then we wanted. Testing alternative implementation of md5-broken I found some constellations and got the idea of hints on images based on a very small part of image of the night sky. This idea was brought to our irc and evolved into the idea of thematic wordlists very fast. So we got the main idea of the contest in 7 hours. It was a great piece of luck. Then it allowed us to totally crack all sha512crypt and descrypt hashes. As soon as full hints were provided elijah[w&p] got a wordlist and rules from Morris worm, using them guth cracked 152 sha512crypt hashes remained after other attacks. With all sha512crypt cracks we did a great jump forward and pushed the score over 50% border in about one day. Thematic wordlists created disbalance and made the contest prone to wordlist-based attacks. But different elements of other attacks were present too. Also things that mimic real life were present. We enjoyed default passwords for descrypt, list of corporate workers for file #11, user names for oracle hashes and other elements. Though we did not fully use the ability to transfer patterns from fast hashes to slower ones (like in pix-md5/keccak and md4/bcrypt pairs). All such elements were miniature. But their exploitation was very interesting for us. At the end of the first day most members went to sleep. It was a good time for sleep. But after that we found us far from the first place. It forced us to develop a real strategy. To make a rational decision I crafted our internal scoreboard sorted by the potential of each hash type because we knew that focused attention to any of hash types could provide us with about all cracks from it. We focused on keccak and bcrypt, also we wasted a lot of time on sha256crypt, other types of hashes weren't that attractive for investment of time. ukasz was the person who efficiently handled a lot of hardware during both days. He used his own computers and our shared development box. Totally he used 4 gpus and several cpus. Other members greatly helped him using just one cpu. Some members noticed that they performed much better with minimal amount of hardware. But such discrepancy in hardware resources forced us to collaborate more. Team work was incredible. Contests improve communication in our community. We like contests very much due to that. This contest seems special due to its thematic wordlists that were very good for our team work. At the second day Frank joined us and directed ukasz to crack bcrypt using patterns found in md4. Frank wasn't on our irc channel and used only our mailing list. Solar warned me that I should post more onto the list to involve list-only members. The advice was invaluable. While the first day was spent mostly in irc the second day brought a lot of messages on the list. A significant number of members joined us on the list during the second day. We got a lot of ideas. Though all useful ideas were investigated before the end. And we had no ideas how to get more points at the end. It was a crisis. But we overcame it, we found new dictionaries. In particular we found Webster's Online Dictionary very useful to crack keccak. Though it had its own price. I was busy cracking and committed neither hashes to organizers nor internal scoreboard to my team. It caused very pessimistic ideas among the team because everyone was tired. Also the situation became very risky: I postponed all possible problems with uploads, and I forgot that uploads are quite slow. Nevertheless I uploaded all cracks 15 minutes before the end. But then our scripts produced broken file for upload, and I am still not sure that we pushed all our cracks while the last 15 minutes produced some due to use of all known passwords as a wordlist. But it was enough for the first place with 91%. The jump to the first place was unbelievable and unpredictable. This "strategic trick" occurred by accident. I was busy cracking hashes and ignored that my team asked me many times to upload our cracks. Now I realize how big a mistake it was. After the jump we weren't happy because all emotions were messed up during these 15 minutes. Regular uploads could make contest more interesting and fun. Automated uploads reduce lags between cracks and uploads to a reasonable time but we did not have automated uploads this time. There was a CSRF shield on the form for submission. So our script for submission of cracks needed changes. We did not implement them. We propose to simplify submission of cracks. Even authentication is not really needed for uploads: you could provide each team with a random number, so team would not need to login but just send this number with cracks. Also we have an idea how to incorporate earlier submissions into the game. There could be a bonus for the first upload. The first team to upload a certain crack gets 1% bonus to this crack's points (small bonus is enough because difference in score between top teams is quite small). Though it would increase the gap between smaller and bigger teams. We are curious why submission of cracks is so slow. Of course it is not a problem with incremental submission. But we could not imagine any real reason for such slow checks on the side of organizers (maybe your DB needs an index?!). We are pleased to say that the quality of the contest was improved significantly. The contest was about solving interesting tasks and not about solving problems just to proceed. Tasks were different. There were minor problems with organization and we would like to see more info in a canonical place at the right time: the perfect contest is when teams do not need to ask organizers. We like that files number 5 and 7 were prepared for additional 12 hours and held (though we would have liked to get info about it at the beginning when we found that these files were empty), it is nice that organizers thought about different cases. Good work! The complexity of the contest matched abilities of big teams well. There is only a bit to crack after the contest. The contest had about nothing significant that needed luck from teams. Top 3 teams are very close so it seems the contest was good for all big teams. But the contest does not seem good for small teams despite efforts of organizers. I'd say it is easier for smaller teams and novices to proceed when at least a small part of each hash type could be cracked using default attack. Also you could decide to add 1 hash of each type with easy and well known password to check that team's cracker works correctly and submission works. There was a disbalance between general brain work and hardware work. Hardware was not critical (though sha256crypt would benefit from bigger hardware resources). This disbalance made the contest very dynamic: most attacks spent less cpu time than human time, results of a hard mind work were about immediate. Themes were very interesting. We enjoyed investigation of Morris worm's code. We puzzled our brains about tomatoes. But points for sha256crypt did not seem right. Though taking into account easy patterns and ability to crack a lot of hashes in a short time it was an attractive target for attacks at the end (sha256crypt was able to add 8% from total to the score). So the points don't look natural but are quite good. Though tricky balance of points makes decisions harder and could make a base for a luck-driven contest. We are looking forward to see detailed statistics and the sources of the contest, so that we can review our decisions. Modifiers to base prices weren't provided during the contest. It added more fog to the situation. It made some decisions harder but not really much. Though in some cases more fog causes more unnecessary problems and more results based on the luck. I guess well defined process at all stages would be more comfortable for all teams. Though well defined contest could become not interesting. Balance here is subtle. Next time it would be nice to see 100% transparent to team members scoring scheme no later than half-way through the contest. Some members like to see their own progress during the contest. They register their own teams and post cracks as two teams. It violated rules this time. One solution could be to keep everything as is now but provide detailed points for hashes right at the start or even earlier so every team could manage any internal point counting system they wish. Another solution is to add a special type of teams - not eligible for prizes. So a person could be in one regular team and in any number of special teams. It may be nice to disable such teams after the first day of the contest to improve cooperation during the end of the contest. Personal write-ups of members You could read more details and personal opinions in members' write-ups: Dhiru Kholia http://openwall.com/lists/john-users/2013/05/27/1 Frank http://openwall.com/lists/john-users/2013/06/01/1 guth http://openwall.com/lists/john-users/2013/06/10/1 elijah[w&p] http://openwall.com/lists/john-users/2013/07/01/2 Jose Luis Herrera http://openwall.com/lists/john-users/2013/07/03/5 Alexander Cherepanov http://openwall.com/lists/john-users/2013/07/05/1 Final words The contest made us better in many ways: we improved relationships, we got experience, we found bugs, we wrote new code. This contest was very interesting. Great thanks for all that! This time we worked as a real team. Everyone supported and helped each other in different ways. We repeated our amazing experience of a great team work and we would like to participate again to improve our tools, our methods and our thoughts. Thanks! -- Regards, Aleksey Cherepanov
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