WhiteHat and the Exploit Factory

Function hooking is a technique attackers use to modify/block/monitor original function calls and their intended purpose. There are a few ways to perform such an attack: Virtual Method Table hooking, Event hooks (ex: keyboard, implemented by Windows), Interception (by overwriting first bytes of the function with a jump) and Import Address Table (IAT) hooking (can be global or internal). This list in not comprehensive, but these methods are the most popular. Let's start with the relatively easy method: interception. To make it visual and simple to follow, let's apply this method to a small program which sums two numbers together and multiplies the result by 2: Once we compiled the program, we want to find magicSum function in the debugger: Here we can see, that after original setup, mathematical calculation is being performed and then we return back to the where this function was called from. In order to intercept this function we will allocate a memory block in the prog...

Dynamically Loaded Libraries (DLL) are used in almost any project, because of their unique properties: modularity, ease to support, updatability. Unfortunately, this can be easily exploited and all it takes is for the attacker to simply replace the original DLL file with the malicious one (especially if project is no longer being maintained and does not have hashing to verify that the valid DLL is being loaded). Moreover attacker can load their DLL into a remote process (usually done to stay hidden, since after DLL is injected you can run malicious code "from within" a target process). To make is easier to visualize, here is a small diagram: For example, we have a program that displays number of seconds passed since it started (not to over complicate things): An attacker can create a malicious DLL that logs pressed keys, but in this case it simply displays a message box: And attacker also has an injector that will load their DLL into the target process: The way an...

To begin understanding why process memory patching is a serious issue we need to understand what it is and how it works. So, without further ado let's answer these questions. Memory patching is modification of process memory in runtime (in this post I am not going to talk about patching binary files). To help you better understand, let's imagine the following scenario: you created a game that has a high score system, user's score is stored in a variable in memory and at game over it is sent to the server. Now, imagine if someone changes the variable in memory right before it is sent. Sounds unfair to other honest players, doesn't it? To better demonstrate how it works I wrote a simple demo in c++ (which you can compile and test on your system). It this post I will be only talking about how it's done in user mode . Target program: Attacker program: First we compile and run a target program, it will display it's process identifier (PID) and a memory loca...

Buffer overflow is a vulnerability, which is usually caused by uncareful handling of user input, but it does not end there. Most of the time it happens when data is being copied into a buffer, which does not have enough space and as a result part of the process memory is being overwritten. It might seem as not that big of a deal at first, but it should not be underestimated. Here is a very basic example of a variable overflow: In this example we are continuously adding 10 to a variable. It may seem like this code will never exit the while statement, because we can keep adding 10 to a variable forever, but that's not quite how it works in programming languages. The thing is that every variable type has some amount of memory allocated to store it's value, thus creating a limit. In this case I created an Integer, which only can store values that can be represented in 4 bytes of space (approximately from -2 billion to +2 billion). When we reach the maximum positive value and ...