Push stack, 'G' giving:
Writing a stack-based overflow exploit in Ruby with the help of vulnserver. Today we will use our trusty workhorse Kali Linux and the tool spike to fuzz a deliberately vulnerable network application on a Windows XP box. From the results of the fuzzing process, we then will create a custom exploit written in Ruby.
The whole post is a remake of Andrew Whittakers fuzzing series on YouTube https: Yet, I prefer to write the exploit in Ruby, because it is the scripting language I am familiar with. To do so we get the tarball from source and put in the directory we want to install it.
Run vulnserver on your Windows box To run vulnserver. Open the run link in your start menu and type cmd.
Now to check if vulnserver is functional just telnet with your Kali box to it: Now to navigate Spike to the function to fuzz we write a short script file.
Just open an editor and enter this code: If we check on the Windows box, vulnserver. Then you need to go to the following entry: Watson serves our purposes well enough. Next we restart vulnserver. We then choose to listen on the interface eth0 and start capturing.
After that, we repeat the above mentioned fuzzing process with Spike and when done stop capturing in Wireshark. We then apply the following filter to the capture ip. Now we can dig through the data by right clicking on the first packet and select the Follow TCP Stream option.
In that case we need to click on Filter Out This Stream to discard that stream from our capture data. Now we go to the next packet, choose the Follow TCP Stream option again and look at the content of the conversation. We see the vulnserver. Since there is no reply in the TCP conversation, we know that this is the part that caused the vulnserver.
We then proceed in Wireshark by selecting only the bytes our Kali box sent to the vulnserver. A simple wc -m on the just saved file that reveals that 1 byte equals one character.
To determine exactly at which memory address the crash occurs we are going to write a Ruby script that sends the open socket of vulnserver.However; it is a little tricky to write the memory address in the user input.
We know that stack works with Last-in-First-Out rule, so we will have to write the address in reverse order. So, the C’s address would be. A stack is an Abstract Data Type (ADT), commonly used in most programming languages.
It is named stack as it behaves like a real-world stack, for example – a deck of cards or a pile of plates, etc. A real-world stack allows operations at one end only. For example, we can place or remove a card or. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Alternate Terms Stack Overflow. I'm looking for a way to quickly calculate the total of the third column and insert it in the buffer. The solution I have in mind would make use of visual-block mode (to select all the numbers) and maybe of the expression register (to do the math).
Implementing a stack with an array: Let's think about how to implement this stack in the C programming language. First, if we want to store letters, we can use type char.
Next, since a stack usually holds a bunch of items with the same type (e.g., char), we can use an array to hold the contents of the stack. At least in Xcode this causes a stack overflow.
These bugs annoy me a lot, while glm library provides almost the same functions but much more stable code. I STRONGLY RECOMMEND you using glm instead of the current buggy vmath.h.
Maybe when all these bugs are fixed, a simple vmath.h would be a better choice, while you need to give up .