Exploiting SEH-based buffer overflows with Metasploit
Exception handlers are code modules that catch exceptions and errors generated during the execution of the program. This allows the program to continue execution instead of crashing. Windows OSes have default exception handlers, and we see them generally when an application crashes and throws a popup that says such and such a program encountered an error and needed to close. When the program generates a specific exception, the equivalent address of the catch code is loaded and called from the stack. However, if we somehow manage to overwrite the address in the stack for the catch code of the handler, we will be able to control the application. Let's see how things are arranged in a stack when an application is implemented with exception handlers:
Figure 3.24 – Address of the catch block in the stack
In the preceding diagram, we can see that we have the address of the catch block in the stack...
