Cyber Apocalypse
2024
Tutorial
Before we start, practice time!
Pwn
300 points
Walkthrough
We start by connecting to the provided server:
nc 83.136.251.7 56503
This presents us with multiple questions, which we can answer to get the flag.
This is a simple questionnaire to get started with the basics.
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◉ C/C++ provides two macros named INT_MAX and INT_MIN that represent the integer limits. ◉
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◉ INT_MAX = 2147483647 (for 32-bit Integers) ◉
◉ INT_MAX = 9,223,372,036,854,775,807 (for 64-bit Integers) ◉
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◉ INT_MIN = –2147483648 (for 32-bit Integers) ◉
◉ INT_MIN = –9,223,372,036,854,775,808 (for 64-bit Integers) ◉
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◉ When this limit is passed, C will proceed with an 'unusual' behavior. For example, if we ◉
◉ add INT_MAX + 1, the result will NOT be 2147483648 as expected, but something else. ◉
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◉ The result will be a negative number and not just a random negative number, but INT_MIN. ◉
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◉ This 'odd' behavior, is called Integer Overflow. ◉
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[*] Question number 0x1:
Is it possible to get a negative result when adding 2 positive numbers in C? (y/n)
>> y
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♠ Correct ♠
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[*] Question number 0x2:
What's the MAX 32-bit Integer value in C?
>> 2147483647
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♠ Correct ♠
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[*] Question number 0x3:
What number would you get if you add INT_MAX and 1?
>> -2147483648
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♠ Correct ♠
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[*] Question number 0x4:
What number would you get if you add INT_MAX and INT_MAX?
>> -2
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♠ Correct ♠
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[*] Question number 0x5:
What's the name of this bug? (e.g. buffer overflow)
>> Integer Overflow
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♠ Correct ♠
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[*] Question number 0x6:
What's the MIN 32-bit Integer value in C?
>> -2147483648
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♠ Correct ♠
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[*] Question number 0x7:
What's the number you can add to INT_MAX to get the number -2147482312?
>> 1337
HTB{gg_3z_th4nk5_f0r_th3_tut0r14l}
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