ghost.c

gistfile1.c

/*
 * Qualys test program to check for presence of GHOST vulnerability
 * For more info: http://www.openwall.com/lists/oss-security/2015/01/27/9
 */
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#define CANARY "in_the_coal_mine"

struct {
  char buffer[1024];
  char canary[sizeof(CANARY)];
} temp = { "buffer", CANARY };

int main(void) {
  struct hostent resbuf;
  struct hostent *result;
  int herrno;
  int retval;

  /*** strlen (name) = size_needed - sizeof (*host_addr) - sizeof (*h_addr_ptrs) - 1; ***/
  size_t len = sizeof(temp.buffer) - 16*sizeof(unsigned char) - 2*sizeof(char *) - 1;
  char name[sizeof(temp.buffer)];
  memset(name, '0', len);
  name[len] = '\0';

  retval = gethostbyname_r(name, &resbuf, temp.buffer, sizeof(temp.buffer), &result, &herrno);

  if (strcmp(temp.canary, CANARY) != 0) {
    puts("vulnerable");
    exit(EXIT_SUCCESS);
  }
  if (retval == ERANGE) {
    puts("not vulnerable");
    exit(EXIT_SUCCESS);
  }
  puts("should not happen");
  exit(EXIT_FAILURE);
}

I have upgrade the libc6 to v2.13-38+deb7u7 on Debian 7.8.

Result of run the ghost.c:

• v2.13-38+deb7u6 >> vulnerable
• v2.13-38+deb7u7 >> not vulnerable

We can upgrade it with under command.

sudo aptitude update ; sudo aptitude safe-upgrade libc6

wget https://gist.githubusercontent.com/amlweems/6e78d03810548b4867d6/raw/69e2fb429dc6f020954405a9d55021db8db1d26e/gistfile1.c && gcc gistfile1.c -o GHOST && ./GHOST

for the people who don't understand C code, a oneliner 😃

glibc 2.20-6 Arch Linux x86_64 Linux 3.18.2-2-ARCH >> not vulnerable

(Ubuntu GLIBC 2.19-10ubuntu2.2) 2.19 >> not vulnerable

Ubuntu EGLIBC 2.19-0ubuntu6.3 >> not vulnerable

Mac 10.10.2 returns errors, so I'm assuming there's no glibc at all...

gistfile1.c:30:12: warning: implicit declaration of function 'gethostbyname_r' is invalid in
      C99 [-Wimplicit-function-declaration]
  retval = gethostbyname_r(name, &resbuf, temp.buffer, sizeof(temp.buffer), &result, &herrno);
           ^
1 warning generated.
Undefined symbols for architecture x86_64:
  "_gethostbyname_r", referenced from:
      _main in gistfile1-00b79d.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

By reading this post I think that gethostbyname and gethostbyname2 should be the equivalent to gethostbyname_r, on MacOS

(Ubuntu EGLIBC 2.15-0ubuntu10.10) 2.15 >> not vulnarable

$ uname -a
Linux xxxxx 2.6.18-348.6.1.el5xen #1 SMP Tue May 21 16:10:52 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux

$ ldd --version
ldd (GNU libc) 2.5

$ gcc --version
gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52)

VULNARABLE