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%p format4 looks at one method of redirecting execution in a process.

Hints

  • objdump -TR is your friend

This level is at /opt/protostar/bin/format4

Source code

(format4.c) download
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#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

int target;

void hello()
{
  printf("code execution redirected! you win\n");
  _exit(1);
}

void vuln()
{
  char buffer[512];

  fgets(buffer, sizeof(buffer), stdin);

  printf(buffer);

  exit(1);   
}

int main(int argc, char **argv)
{
  vuln();
}