The Developer’s Pandora Box: Exception Handling (Part 1)

The exception handling is one of the common features of the Operating System together with programming language runtime. It is very closely related to software security. The programming language like C/C++ together with OS capability can guard a piece of code against the software exceptions by adding a handling construct or exception handler. It is commonly observed that programmers use the exception handler to start execution at another location however a specific type of exception can be handled with a specific exception handler. This is one of the most widely used mechanisms in the software industry and part of almost all programming languages. This is why it is of utmost importance for security researchers, developers and IT administrators to have in-depth knowledge of this mechanism.

This post introduces the concept and highlights a few important questions on the internal working of the Structured Exception Handling (SEH) for better understanding. This is the first post of an upcoming long series of posts where we will dissect the internals of Exception Handling. Every post in this series will include some reverse-engineering of the sample program and its explanation to understand the internal structure and flow. It is expected that the reader has some knowledge of C and WinDbg or any other related debugging tool.
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