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Baby's Third

Babies can't count, but they can do binaries?

Author: ElykDeer

readme.txt babysthird

I first ran the binary in order to see what it does.

$ ./babysthird
Enter your password:

Using the checksec utility, I saw the security properties of the file.

$ checksec babysthird 
[*] '/home/hacker/csaw23/babysThird/babysthird'
    Arch:     amd64-64-little
    RELRO:    Full RELRO
    Stack:    Canary found
    NX:       NX enabled
    PIE:      PIE enabled

  • There's two important properties here:

    • NX enabled: This means that the stack is not executable. Therefore we cannot use a shellcode injection.

    • PIE enabled: This means that the executable is positionally independent. So the code and memory regions will have the same address every time we run it.

  • Before disassembling the executable, I opened the readme.txt file and saw an interesting line.

Most notably, binutils includes `objdump` and `strings`. One of those are what you need to solve this challenge...

  • So, then I used the strings utility to see if the flag was stored somewhere in plaintext.

And there was the flag!

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