Wampserver 3.0.6 - Insecure File Permissions Privilege Escalation

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# Vendor Homepage: http://www.wampserver.com/
# Date: 10 Dec 2016
# Version : Wampserver 3.0.6 32 bit x86
# Tested on: Windows 7 Ultimate SP1 (EN)
# Author: Heliand Dema
# Contact: heliand@cyber.al
=====================================================
 
Wampserver installs two services called 'wampapache' and 'wampmysqld'
with weak file permission running with SYSTEM privileges.
This could potentially allow an authorized but non-privileged local user
to execute arbitrary code with elevated privileges on the system.

C:\>sc qc wampapache
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: wampapache
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 3   DEMAND_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   :
"c:\wamp\bin\apache\apache2.4.23\bin\httpd.exe" -k runservice
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : wampapache
        DEPENDENCIES       : Tcpip
                           : Afd
        SERVICE_START_NAME : LocalSystem



PS C:\> icacls c:\wamp\bin\apache\apache2.4.23\bin\httpd.exe
c:\wamp\bin\apache\apache2.4.23\bin\httpd.exe
BUILTIN\Administrators:(I)(F)                    <--- Full Acces
                                              NT AUTHORITY\SYSTEM:(I)(F)
                                              BUILTIN\Users:(I)(RX)
                                              NT AUTHORITY\Authenticated
Users:(I)(M)           <--- Modify


C:\Windows\system32>sc qc wampmysqld
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: wampmysqld
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 3   DEMAND_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   :
c:\wamp\bin\mysql\mysql5.7.14\bin\mysqld.exe wampmysqld
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : wampmysqld
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem


PS C:\> icacls  c:\wamp\bin\mysql\mysql5.7.14\bin\mysqld.exe
c:\wamp\bin\mysql\mysql5.7.14\bin\mysqld.exe
BUILTIN\Administrators:(I)(F)                <--- Full Acces
                                             NT AUTHORITY\SYSTEM:(I)(F)
                                             BUILTIN\Users:(I)(RX)
                                             NT AUTHORITY\Authenticated
Users:(I)(M)       <--- Modify


Notice the line: NT AUTHORITY\Authenticated Users:(I)(M) which lists the
permissions for authenticated however unprivileged users. The (M) stands
for Modify, which grants us, as an unprivileged user, the ability to
read, write and delete files and subfolders within this folder.


====Proof-of-Concept====

To properly exploit this vulnerability, the local attacker must insert
an executable file called mysqld.exe or httpd.exe and replace the
original files. Next time service starts the malicious file will get
executed as SYSTEM.