Skip to content
Branch: master
Clone or download
Type Name Latest commit message Commit time
Failed to load latest commit information. Add game's official website Mar 13, 2019
SdoKeyCrypt.i64 Upload IDA analysis file Mar 12, 2019
pic0.png First commit Mar 12, 2019
pic2.png First commit Mar 12, 2019
screenshot.gif First commit Mar 12, 2019

SdoKeyCrypt.sys - Local Privilege Elevation Vulnerability

1. What is SdoKeyCrypt.sys?

SdoKeyCrypt.sys is a keyboard protection driver for a MMORPG, aka Massively-Multiplayer-Online-Role-Playing-Game, called MapleStory Online which is published by Shanda Group in China.

The game's official website: (Language: Chinese)

This driver will be downloaded and installed in C:\Windows\System32\ folder when the game runs first time. Because the game is very big, approximately 13.11 GB, here I made a backup SdoKeyCrypt.sys for anyone who wants to reproduce this exploit.

SdoKeyCrypt.sys is surely OFFICIAL and is NOT modified by anyone.

You can see there's a valid digest signature signed by Shanda Computer (Shanghai) Co., Ltd. which confirms SdoKeyCrypt.sys is indeed made by Shanda.

2. What is the vulnerability caused by?

In IRP_MJ_DEVICE_CONTROL handle routine, when IOCTL code is (DWORD)(-0x7FFF3FFC + 0x18) = 0x8000c01c, the driver does not properly handle data passed from user space, which causes a size value can be negative so that a heap underflow will occur.

With the help of heap spraying, aka pool-Feng-Shui attack, one can disable SMEP and run any shellcode in kernel mode to make local privilege elevation.

3. How to use PoC code?

With x64 Microsoft Visual C++ compiler (which supports c++11)

$ cl poc.cpp /Fe:poc.exe /link /dynamicbase:no /fixed ntdll.lib

Tested on Visual Studio 2017 Community, the following is an example of output:

C:\Github\SdoKeyCrypt-sys-local-privilege-elevation>cl poc.cpp /Fe:poc.exe /link /dynamicbase:no /fixed ntdll.lib
Microsoft (R) C/C++ Optimizing Compiler Version 19.16.27027.1 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

Microsoft (R) Incremental Linker Version 14.16.27027.1
Copyright (C) Microsoft Corporation.  All rights reserved.


Then make sure that SdoKeyCrypt.sys is loaded and run poc.exe directly. If nothing wrong, you should get a nt authority\system shell.

4. Screenshot

The PoC code has been tested and works fine on Win10 1709 and Win10 1803.

However it does not work on Win10 1809 which uses heap-backed pool that mitigates heap-spray attack. But it can cause BSOD, so there's local Denial-of-Service vulnerability at least.

The following is a test video on Win10 1803 17134.619.

You can’t perform that action at this time.