# Exploit Title: BlueStacks 2.5.55 Unquoted Service Path Privilege Escalation
# Date: 24/09/2016
# Author: Yunus YILDIRIM (@Th3GundY)
# Team: CT-Zer0 (@CRYPTTECH)
# Website: http://yildirimyunus.com
# Contact: yunusyildirim@protonmail.com
# Category: local
# Vendor Homepage: http://www.bluestacks.com/
# Version: Software Version <= 2.5.55
# Tested on: Windows 7-10 x86/x64

1. Description

BlueStacks Log Rotator Service (BstHdLogRotatorSvc) installs as a service with
an unquoted service path 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.


2. Proof of Concept

C:\>sc qc BstHdLogRotatorSvc
[SC] QueryServiceConfig SUCCESS
SERVICE_NAME: BstHdLogRotatorSvc
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 3   DEMAND_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\Program Files (x86)\Bluestacks\HD-LogRotatorService.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : BlueStacks Log Rotator Service
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem


3. Exploit:

A successful attempt would require the local attacker must insert an executable file
in the path of the service.
Upon service restart or system reboot, the malicious code will be run with elevated privileges.


Additional notes :

Fixed in version v2.5.61

Vulnerability Disclosure Timeline:
=========================
24/09/2016   -   Contact With Vendor
28/09/2016   -   Vendor Response
04/10/2016   -   Release Fixed Version