These days we are simply surrounded by different software frameworks. Just to name a few: Java, .Net and, actually, many more. Have you ever wondered how those work or have you ever wanted or needed to implement one? In this article, I will cover a simple or even trivial runtime framework.

One of the aspects of software anti RE (reverse engineering) protection is the need to protect sensitive data (for example decryption or license keys, etc.) There is quite a common practice of storing such data in encrypted form and using it by passing to a certain routine for decryption. I am not going to say, that this is not a good idea, but the problem with such approach is - vendors (in most cases) only rely on the complexity of the encryption algorithm, which is not as protective as it is thought to be and too often is placed in a single function (which, potentially, may be ripped and used with malicious intent).

There has been said and written too much on how software vendors do not protect their products, so let me skip this. Instead, in this article, I would like to concentrate on those relatively easy steps, which software vendors have to take in order to enhance their protection (using packers and protectors is good, but certainly not enough) by not letting the whole code appear in memory in readable form for a single moment.

So. Executable code injection. In general, this term is associated with malicious intent. It is true in many cases, but in, at least, as many, it is not. Being malware researcher for the most of my career, I can assure you, that this technique appears to be very useful when researching malicious software, as it allows (in most cases) to defeat its protection and gather much of the needed information. Although, it is highly recommended not to use such approach, sometimes it is simply unavoidable.

In this article I will cover the easiest way to hide your injected library from the "victim" process. Intentionally or not, but we will have to dive a bit into Windows internals starting with the TIB (Thread Information Block) and ending with good old UNICODE_STRING data structure.