Notes

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# Quick Stack Based Buffer Overflow For Tim #
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- You can download everything you need for this exercise (except netcat) from the link below
https://s3.amazonaws.com/StrategicSec-Files/SimpleExploitLab.zip

- Extract this zip file to your Desktop

- Go to folder C:UsersWorkshopDesktopExploitLab2-VulnServer, and run vulnserv.exe

- Open a new command prompt and type:
nc localhost 9999

- In the new command prompt window where you ran nc type:
HELP

- Go to folder C:UsersWorkshopDesktopExploitLab4-AttackScripts
- Right-click on 1-simplefuzzer.py and choose the option edit with notepad++

- Now double-click on 1-simplefuzzer.py
- You'll notice that vulnserv.exe crashes. Be sure to note what command and the number of As it crashed on.


- Restart vulnserv, and run 1-simplefuzzer.py again. Be sure to note what command and the number of As it crashed on.

- Now go to folder C:UsersWorkshopDesktopExploitLab3-OllyDBG and start OllyDBG. Choose 'File' -> 'Attach' and attach to process vulnserv.exe

- Go back to folder C:UsersWorkshopDesktopExploitLab4-AttackScripts and double-click on 1-simplefuzzer.py.

- Take note of the registers (EAX, ESP, EBP, EIP) that have been overwritten with As (41s).

- Now isolate the crash by restarting your debugger and running script 2-3000chars.py

- Calculate the distance to EIP by running script 3-3000chars.py
- This script sends 3000 nonrepeating chars to vulserv.exe and populates EIP with the value: 396F4338

4-count-chars-to-EIP.py
- In the previous script we see that EIP is overwritten with 396F4338 is 8 (38), C (43), o (6F), 9 (39)
- so we search for 8Co9 in the string of nonrepeating chars and count the distance to it

5-2006char-eip-check.py
- In this script we check to see if our math is correct in our calculation of the distance to EIP by overwriting EIP with 42424242

6-jmp-esp.py
- In this script we overwrite EIP with a JMP ESP (6250AF11) inside of essfunc.dll

7-first-exploit
- In this script we actually do the stack overflow and launch a bind shell on port 4444

8 - Take a look at the file vulnserv.rb and place it in your Ubuntu host via SCP or copy it and paste the code into the host.


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cd /home/strategicsec/toolz/metasploit/modules/exploits/windows/misc

vi vulnserv.rb (paste the code into this file)



cd ~/toolz/metasploit

./msfconsole



use exploit/windows/misc/vulnserv
set PAYLOAD windows/meterpreter/bind_tcp
set RHOST 192.168.88.129
set RPORT 9999
exploit