How do you take user input as hex characters through gets() function? (Linux)

Question

Hello guys I'm learning about buffer overflows and and working on how to enter the correct attack payload that would modify the return address to a specific function within a c program.

The example is below of an array of char size 0-13 (0-12+Null) and my target address is 0x080484C7.

 char buffer[14]
 gets(buffer);    

I've determined the location of the return address on the stack but, through user input using the gets() function I'm unable to correctly enter the address and have attempted entering input as \xC7\x84\x04\x08 to specify hex but, it takes in each backwards slash, numerical value and alpha letter as (ascii) entering the wrong hex values.

How can I enter in specific hex values through the gets function via user input in linux?

Answer 1

You could use echo to output the desired characters and then pipe it into your program:

echo -e "\xC7\x84\x04\x08" | ./yourprogram