Notes

PROG
1. n^2-n+41 primes less than trillion .
2. Connect to nullcon-e1.no-ip.org:2000 .
3. Mr. X is fond of prime numbers. Recently, Mr. X learnt of some special numbers called Smarandache-Wellin numbers. The n'th Smarandache-Wellin number is obtained by concatenating the first n primes. For example, 2, 23, 235, 2357, 235711 are the first 6 decimal Smarandache-Wellin numbers. Mr. X is interested in binary Smarandache-Wellin numbers. Furthermore, Mr. X is only interested in those numbers which are prime. He found the first 3 such numbers 2, 11 and 751 and now needs your help in finding the next 2 numbers. Enter the next 2 binary Smarandache-Wellin primes. The flag is the MD5 hash of the next 2 binary Smarandache-Wellin primes separated by _ (underscore). For eg. if the numbers are 23 and 235, the flag would have been MD5SUM("23_235").

4.Given N = 80000000000000000 K = 5996159730031 M = 9828343043 Compute the Binomial Coeffcient C(N, K) modulo M. Flag is the MD5 hash of the answer.

5.Win 100 games of cows and bulls to get the flag. Play here: nullcon-e1.no-ip.org:2002

Crypto
1. https://s3.amazonaws.com/Nullcon/2013/BU/Crypto/clevel1.zip

2. Decrypt the chatlog to get the key. https://s3.amazonaws.com/Nullcon/2013/BU/Crypto/chat.txt

3. Decrypt the message. It was encrypted using the nullcon-e1.no-ip.org:3002. AtDGJVgVeiW7vawk3/otNhXQolJ+SBdzqOcObwaWvEdSDQVu+9YcMNf2iTBv pwNTZUrSQZxyaSUEbMhgmIJ2Z32HhjeuXF40FdnuRFW5jXC0WbUp6BdYJbhM AzMgz0UiG5bNMWORywmAPfYhYxuMI6K1QiEnC+UiMXaqJT7rPiUYlWckTKm5 IvsyEyWSZFAkQIjKIuNw9SWi4JQlIIBTJdx+0STU/MwjxPjDIeuR5yOyorkh ByUTI2oJUCC3csAgEYXgIUVqoSPmkywhr0c5IgHvEiQenU8iX1r/JNoz6SPQ Zrwhw60YI+IaWyCnVdYgMcvMIQX2+SNm650hr7ZbIw==

4. Decrypt the message. It was encrypted using the nullcon-e1.no-ip.org:3003. yKZXLjrO3zYnqrkwGxwcNppKnVnzNcp+k0oJLu/zj3+70sZ+TP2rJhTvLXp7 qMBf6ofTMx3K4yKB0f00TWivecB0Nn72QEQu4xuHXGLYGTdNZtg1pgyiN6yo HSTmtI0qZJZeMTGatyn4TXMhzPL9JHC6nyA2ceYmq+kaJp3LOCKpNLcgg8pg IN2PVCHfMZQjVuu8IPxYPiGwzFcm3qHfI3Z0QiMk0zsjh1AjI9YDpiIET9Ak lWxzJXEHLSS3H7Uh8LsBIoMH+iDbYh0k2gn8JHzp3CepCTwgo/ZlJtXRiyB1 19AgmlZiJR6w5iPhfTclCUsaITti+CWDwo0kaohwIA==

5. Decrypt the messages to get the key. https://s3.amazonaws.com/Nullcon/2013/BU/Crypto/clevel5.zip

Reverse
1. I read memory. Flag is the MD5 sum of answer string.https://s3.amazonaws.com/Nullcon/2013/BU/RE/01.zip

2. Look deep. https://s3.amazonaws.com/Nullcon/2013/BU/RE/02.zip

3. Avoid the crash to get the key. https://s3.amazonaws.com/Nullcon/2013/BU/RE/03.zip

4. Give me serial, I give you key. https://s3.amazonaws.com/Nullcon/2013/BU/RE/04.zip

5. Good luck with this one. https://s3.amazonaws.com/Nullcon/2013/BU/RE/05.zip

Exploit

1. Login to: http://nullcon-e2.no-ip.org/

2. Chat with friends: http://nullcon-e2.no-ip.org/chat

3. Lets do some PHP: http://nullcon-e1.no-ip.org/exp3/boo.php

4. Exploit the daemon at nullcon-e3.no-ip.org:6791 to get the key. https://s3.amazonaws.com/Nullcon/2013/BU/Exploitation/srv.tar.bz2

5.


Misc

1. Who wrote the private key on whiteboard just by looking at the public certificate?

2. Here you go. https://s3.amazonaws.com/Nullcon/2013/BU/Misc/8cb94a0d097f0fc0b34fe9729c6ce11c.tar.bz2

3. Piece of cake.. really. https://s3.amazonaws.com/Nullcon/2013/BU/Misc/m2.gz

4. Correlate and make sense. https://s3.amazonaws.com/Nullcon/2013/BU/Misc/28565c07f336beff94511205e2c008d1.tar.bz2

5. l33t CnC for fun and profit. https://s3.amazonaws.com/Nullcon/2013/BU/Misc/l33t_cnc.tar.gz