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[Write Up] CTF CODEBALI 2015

October 13, 2015 | Posted in How to

One Does Symply - Reverse


one_does_symply


$ file one_does_symply
one_does_symply: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.6.26, BuildID[sha1]=1777b84271052131d7b983c64087a22b01c667a3, not stripped

file ini adalah sebuah ELF 32-bit binary dan jika dijalankan


$ chmod a+x one_does_symply
$ ./one_does_symply


Enter Key :

harus memasukkan key? sedangkan tidak mengetahui keynya. jika memasukkan key dengan asal maka


$ ./one_does_symply


Enter Key : AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

lose

selanjutnya menganalisa dengan menggunakan radare2 dan dilanjutkan membaca fungsi main dari ELF tersebut


$ r2 -A one_does_symply


radare2


flag BALI{4944a352dfbbb611e1c50197c024add3}




Simple Chiper - Crypto


Hackers can solve a simple cipher. Are you a hacker? Can you decode this?

0124 1101000 101 100000 01000011 01001111 68 0105 66 65 1001100 1001001 100000 105 1110011 040 116 1101000 0145 040 1100010 0151 103 103 0145 1110011 0164 100000 1101000 0141 99 6b 1100101 0162 32 0143 111 1101110 1110100 101 0163 0164 040 0151 0156 040 66 0141 01101100 01101001 056 4f 0157 0160 115 44 040 0171 1101111 117 100000 1110111 0141 0156 1110100 32 0164 6f 32 6b 1101110 1101111 1110111 100000 0164 1101000 0145 040 0146 6c 97 1100111 2c 100000 0144 111 110 100111 116 100000 1111001 6f 117 63 0110 1100101 0162 0145 100000 1111001 111 117 100000 97 114 0145 46 01000010 0101 0114 73 123 87 110011 110001 67 110000 1001101 51 32 55 060 100000 110111 0110 110011 32 0103 060 0104 51 01000010 0101 76 0111 32 0103 1010100 70 32 062 060 49 065 7d 1001000 0141 1110110 1100101 100000 102 0165 0156 33


Using python script solver.py can solve the simple cipher.

$ python3 solver.py > output.txt
$ cat output.txt
The CODEBALI is the biggest hacker contest in Bali. Oops, you want to know the flag, don't you? Here you are. BALI{W31C0M3 70 7H3 C0D3BALI CTF 2015} Have fun!

flag BALI{W31C0M3 70 7H3 C0D3BALI CTF 2015}












Taged in: codebali, write