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I must intercept execution in very big application in many places.
What programs I can use to do this? What techniques exists for this problems?
Manually reverse engineering and adding hooks is maybe not optimal solution for this problem, because application is very big and some part of application can be updated in some time, i think with some tools or good practices for this problem i can do this faster, anyone know how to do?
Anybody help me?
seeing as the tools part has been covered, here is something for the techniques.
Depending what it is you need to hook and whether or not there is protection invloved, there are a few methods:
Relative call/jmp patching in the virtualized binary: this is the simplest, but also a lot of work if you can't automatically find all references to a function, this probably won't work in this cause due to your criteria.
IAT/EAT hooking: this is use for imports(IAT) and exports(EAT), great if your targeting a known importted/exported set of API functions. a good example of this can be found here or here
Hot-Patching: Windows XP SP2 introduced something called "hot-patching" (used for realtime system function updates), where all its (the WinAPI) functions start with a 'mov edi,edi', allowing a relative jump to be patched into the free space created above every hot-patchable function(one can do it too). this is generally used for programs that checksum there IAT's or have other funny forms of protection, more info can be found here and here
Code-Caving: capturing execution flow by placing redirections in arbitrary code space. see here, here or here
VFT/COM Redirection: basically overwriting entries in a objects virtual function table, useful for OOP/COM based applications. see this
There are a lot of 3rd party libraries, most famous would probably be MS Detours, one can also look at APIHijack or a mini-hook engine.
Ofcourse nothing can substitute for the initial poking you'll need to do with a debugger like ollydbg, but knowing the method your gonna use can drastically short them amount time time spent poking around
Some details on what exactly you need to do (e.g. how do you determine where to break) would be nice. Depending on your situation, something like Pin might work.
I suggest using Deviare API Hook. It's the easiest way you can do what you need. It has some COM objects that you can use to hook an application from a different process. In your process you get full parameter information and you can use it in any programming language (I'm using C# and it works like a charm).
If you need to intercept registry API I suggest using Deviare to debug what you need to intercept but then you will have to make your own hooks, otherwise, you'll find performance issues.
You can do API Hooking if you are interested in intercepting method calls.
Or use some disassembler like softice or ollydbg or win32dasm.
I am using a rather obsure, proprietary langauge called WIL/Winbatch that had an awful IDE (winbatch studio).
I would like to develop an alternative environment; however, without the ability to set breakpoints, step, and examine variables, there is really no point. How does one begin even researching how to implementing a debugger for a proprietary language? Is it even legal?
I guess I'm kind of locked in a mindset that the debugger portion must be able to examine the statements that are provided to it in WIL as they are executed, right? So somehow i have to trap the output of the interpreter? Or is it just a matter of reading locations in memory using whatever language?
Thanks in advance.
Having been there and successfully completed the task, here are the things to keep in mind:
Build it as a plug-in/extension to an IDE your team is already familiar with and likes. They'll thank you for providing an interface consistent with what they really know how to use, plus you can focus entirely on the features that make your language different from others.
You'll have to learn the debugging protocol for your language. In our case, we had source access to the runtime for the interpreted language. In other cases, you may find documentation for GDB local or remote debugging interface, a library you can link to for the language's debugging protocols, or maybe even figure out what the call stacks look like and wrap the Windows Debugging API to analyze it behind the scenes.
Don't build in excess of what the language provides. Adding debugging features takes a lot of time, and they have a rather annoying habit of needing to be significantly altered or completely rewritten as versions of the target language are updated.
Why are you tied so closely to this language? If it's not well supported, there are many others you can use. Anyway, to actually answer your question, the difficulty depends on whether it is a compiled or interpreted language and whether or not you have access to any source code (which it seems of course, that you don't). That said, this would be a very challenging project as you would have to reverse engineer the compiled code for it to have any meaning. Your time would be better spent learning another (better) language.
Perhaps if you can give us an idea of why you want to use this language we could give you some help?
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I was certain that somebody would have specifically asked this question, but from what I can see no-one has (there's been a question about learning win32 but that doesn't cover whether it's worthwhile doing so).
I am very interested in gaining a deeper understanding of all the systems I use (I mostly program in C#, at least professionally), so I wondered, very simply - is learning win32 worthwhile, or is it overkill? Am I wasting my time? Is the knowledge I'd gain worth the effort?
Similar / related questions on StackOverflow:
Does it still make sense to learn low level WinAPI programming?
How relevant is Win32 programming to modern professionals?
Having a working knowledge of how Win32 works at the lowest level will certainly be invaluable if you are planning on doing Windows development in the future. It gives you a level of insight into things like Windows, Messaging and GDI that are hidden by the time you get to the level of .NET.
I wouldn't recommend you try and use Win32 for writing all your applications, but I feel that any Windows developer would benefit from writing a simple Win32 application using C/C++.
This is less true for things like WPF where there is less dependency on Win32, but just knowing how Win32 works will help you understand or appreciate some of the design decisions in WPF.
I advocate learning the concepts behind low level windows programming if all of the following are true.
You are going to do any windows programming.
You want to be the "go to" guy when the unexplainable happens.
You love to learn.
Abstraction layers like .NET work create and allow developers to do incredible things without having to know a lot. However, when .NET is used in a way unanticipated by its authors which reveals one of its subtle bugs, then that is the time where some win32 API knowledge goes a long way.
Will you ever have to write a message pump? I doubt it. Can it help diagnose problems? You betcha!
The question is much like, "Is learning assembly worthwhile"; and the answer is the same:
"Yes, because you will understand the fundamentals, and be able to perceive deeper than those who only work at the top level of abstraction".
However, by the same token, you probably won't be writing Win32 API directly 99.5% of the time.
When they invented C to replace assembly language, people where probably asking: "is it worthwhile to learn assembly language?" The value in knowing both was being able to drop to assembly to do the things which were impossible to accomplish in C (eg. trigger an interrupt).
The same can be said for Win32. There are some things which are impossible to do in C#. If you didn't know the win32 api, then you would dismiss some things as being impossible. However, once you know what you are missing, in those rare situations, you would be able to "drop to win32" and do them.
Another way of looking at it is this: programming is all about being able to think in multiple levels of abstraction at the same time. For example, if you know your language uses immutable strings, you don't write an algorithm that adds a single character to one 10000 times, because it will be slow. If you know the win32 api, you will be able to think about how each line you write in C# is actually implemented and that will help you write better code.
At least for me, learning an API (I'm assuming that "in-depth" is implied) that I don't use is a waste of time. I'd rather spend my limited amount of time and brain power learning new concepts or exploring new tools than becoming intimately familiar with an existing tool that I don't need to use now. When I need a particular tool that I don't have or have to use a tool that I'm not familiar with, that's the time to learn it in some depth. Before that I might do enough investigation to know whether it is going to be useful to me or not, but not much more.
Yes, the principles of the Win32 API are useful to learn - these principles are the foundation on which everything else is built.
The .NET APIs for GUI development, both Windows.Forms and WPF, do what they do within the constraints of what is possible on top of the Win32 API. Key architectural decisions of these frameworks were constrained and informed by the Win32 API.
On the other hand, you are less likely to get a lot of value from diving deep into the API, as there is a lot to learn, and given that you spend most of your time working in C#, you'll have less opportunity to use the knowledge directly.
BTW, the same applies to other technologies as well - like networking, cryptography and hardware design. Learning the fundamentals will help you become a better developer.
Yes, you should learn the basics of how Windows (a lot of this stuff predates Win32) operates. Why? For the same reason as I understand how a mortise and tenon joint operates, even though I don't make my own furniture, or why I understand how an internal combustion engine works even though I don't do my own car maintenance.
You work at a higher level of abstraction, which is nice, but when that abstraction leaks - that's not an "if", that's a "when" - if you don't understand the basics of Windows, you'll be lost. If you don't know at least some of the API, you won't have a clue where to look if you need to P/Invoke functionality not available in .Net.
Quite apart from that, isn't curiousity reason enough?
If you are trying to write a VB6 application then the Win32 API allows you to do a lot of things that are not natively supported by VB6.
If you're writing a C# WinForms app then I would recommend learning the vast reaches of the .NET Framework first.
Edit
If you really want to know what's going on under the hood in Windows then you might want to check out a copy of Programming Windows 3.1 by Charles Petzold.
I personally think it's still worthwhile learning the Win32 API.
As far as I recall when I started learning Win32 (after doing some VB(A), Pascal, etc.) I learned a lot about Windows and understood how thing works in Windows. Everything was so clearer. :)
So, as per your question - you will learn a lot about Windows through learning Win32.
As you said - you're a C# programmer and I'm not sure if you'll use it often, because almost everything you need is already there, in .NET.
I won't repeat over and over what the others said many times already.
Here's a link to a Win32 tutorial with which I am currently learning along the basics of Win32's. I find it pretty interesting and easy to follow.
This tutorial helps me get what I didn't understand first, back when I've begun to program in my secondary school years.
If I were to start today, I wouldn't learn the entire API. However, I do think that the basic concepts are important to understand, with an understanding of how message loops work as the top priority.
You'll never be able to just "learn" the entire win32 API, it's too much to take in, and it will be a moving target. If you develop in C#, there's no real point.
That said, try creating Notepad using plain C and just API calls. That will teach you enough for a C# developer to at least appreciate it.
A lot of the "No" answers here seem to focus on learning the actual methods, structs, and what not available in the API. I'd say yes, but focus not on the individual components of the API, but the overall design and the way it functions. It's much easier to troubleshoot even .NET code when you understand what's happening at the core level of the operating system.
This question looks a bit dated, but I'll answer anyway.
Answer: Complicated: yes. Simple: probably not necessary.
It really depends on what you need to do. If you need to use a feature not current supported by .NET, have-at-er. But be careful, most of the coddling the Framework provides Win32 does not, and if you do something incredibly stupid, your machine WILL bluescreen.
I know when .NET first came out, I had have no interest to learn Win32, .NET was here and it was such an improvement. But the sad fact about Windows is this: all new features in Windows are implemented in native code first, period. If you want to use any part of Windows before .NET wraps it, you're either using Win32 from C++ or Win32 from C# or from VB.NET. .NET is a wrapper, for all the stuff in Win32. So if you can't wait, yes, you can Interop into the lower bowels of the OS if you'd like.
Knowing Win32 and probably one day Win64 (whatever they happen to call it) will always be a useful skill. Any whizzbang technology requires underpinnings somewhere.
.NET is implemented using win32 api, anyone wishing to possess deeper understanding of .NET would greatly benefit from having at least marginal knowlege of win32api.
In your career it will be unlikely that you will only be creating greenfield applications where you will have the freedom to choose the technology and programming languages used.
Sooner or later you will have to integrate with old code written in Win32 and C/C++. In that case, knowledge of Win32 will help, especially if you are integrating using PInvoke or C++/CLI.
Misuse the .NET framework and Win32 and your machine will blue screen? Somehow I doubt that.
The biggest value to knowing Win32 (or assembly language) is that when something doesn't work as expected and you have to debug it. The more you know about the underlying system, the easier time you will have debugging the problem.
I like to further add to this. I never formally studied Win32 API/MFC. I started using Visual C++ 4 when I first got interested in GUI programming. Anyway, I wish I kept that foundation then, as I never caught on quick enough (I was rather young then, actually), so I studied Visual Basic instead.
For some reason, Delphi never interested me even though I knew Pascal well enough, but I digress. These days, I work in IT and develop installer scripts in NSIS - and every so often I need additional functionality that NSIS doesn't provide, so I make my own plugin and to keep it quick and dependency free, I opt for Win32 API opposed to MFC or even full blown C++.
The main reason for this comment, is that my own curiosity got me hooked. I like to know more, so where is the best resource for learning the API. A book? Website?
Would MFC still be worth tackling as well? I did see a website about a fellow that develops Win32 GUI apps, in assembly! I think that is overkill, honestly, but it is compact, fast code, interesting, the concept, but I never was able to get the hang of 80x86 assembly (hell, even RISC assembly in college I never was able to do!)
I think it's always interesting to know how a system works if your work relies on it. I don't mean you should learn every bit of it, but still get a good understanding, at least to be able to search more by yourself the day you will have to.
Software is not magic - well... ok... for 99% of the cases :-)
Here is a link to an excellent article about "magical thinking" and "GUID goblins" from Eric Lippert's about that subject: It's not Magic
I have a home-spun 2000 lines VBScript script, that has become progressively slow with each additional code I add. It was created as a private debugging aid and now that it has become really useful. I want to polish it and ship it along with our product.
I thought I could speed it up by compiling it and making it an EXE. Furthermore I want to have a user interface for my tool, which might be possible once I use the extra libraries that the compiling platform might give me. I'm also considering extending the script by calling Win32 functions for whatever missing functionalities I require.
I have VB 6.0 or I can buy an external compiler. But I also need the created program (not the compiler itself) to run fine in Windows Vista. What are my best options?
I would recommend downloading Visual Basic Express Edition (http://www.microsoft.com/express/vb/) and port your tool to VB.Net. However, that approach has one drawback - your program will be dependent on .Net. For the most part that shouldn't be a big problem, as by now most machines should have .Net 2.0, still it's better to keep it in mind.
I would stay away from VB6.0; however, aside from VB.Net I don't know any other good Basic compilers you could use.
There's probably more to the slowness than just the fact it's being interpreted. There are probably various optimisations you could make to it to make it faster. Try finding which parts of the code slow it down the most and try to speed them up.
Depending on what the code does VB6 could be fine. If it'll be dealing with natural text/filenames, then it would be better to use VB.net, 'cause VB6 doesn't support Unicode well.
But I get the feeling that even after compilation, it could still be slow, because compilation will only make it run faster, but not more efficiently.
Well ... there are a number of "good" BASIC compilers out there:
BCX
xbLite
are the ones that come to mind immediately. Quite a few are listed on the mindteq site. (Jabaco is particularly interesting - VB6 re-expressed in Java. I've fiddled with it, and it looks very promising!)
But getting back to VBScript compilers, they do exist .. sort of. What they do is tokenise the code and put some kind of wrapper around them. Whether they run any faster is moot.
VBS2EXE
VBScript2Exe
ExeScript
It's hard to say without knowing more of what the program is doing or how much data it's processing.
I agree with Franci - VB6 is no longer sold or supported so VB.Net would be the way to go for compiled code. (Express is free.) VBScript is not very much like VB.Net, so that might be a good bit of work to port unless it's all WMI or LDAP queries or something like that.
I would start out timing things to see where your bottlenecks are. Unless you're doing tons of looping and multi-level function calling you're probably stuck on external calls.
wscript.echo "Begin: " & Time
tStartTime = Timer
'... do stuff ...
tStopTime = Timer
wscript.echo "Elapsed time: " & tStopTime - tStartTime
Cheers
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Closed 10 years ago.
Does it make sense, having all of the C#-managed-bliss, to go back to Petzold's Programming Windows and try to produce code w/ pure WinAPI?
What can be learn from it? Isn't it just too outdated to be useful?
This question is bordering on religious :) But I'll give my thoughts anyway.
I do see value in learing the Win32 API. Most, if not all, GUI libraries (managed or unmanaged) result in calls to the Win32 API. Even the most thorough libraries don't cover 100% of the API, and hence there are always gaps which need to be plugged by direct API calls or P/invoking. Some of the names of the wrappers around the API calls have similar names to the underlying API calls, but those names aren't exactly self-documenting. So understanding the underlying API, and the terminology used therein, will aid in understanding the wrapper APIs and what they actually do.
Plus, if you understand the nature of the underlying APIs that are used by frameworks, then you will make better choices with regards to which library functionality you should use in a given scenario.
Cheers!
I kept to standard C/C++ for years before learning Win32 API, and to be quite blunt, the "learning Win32 API" part is not the best technical experience of my life.
In one hand Win32 API is quite cool. It's like an extension of the C standard API (who needs fopen when you can have CreateFile. But I guess UNIX/Linux/WhateverOS have the same gizmo functions. Anyway, in Unix/Linux, they have the "Everything is a file". In Windows, they have the "Everything is a... Window" (no kidding! See CreateWindow!).
In the other hand, this is a legacy API. You will be dealing with raw C, and raw C madness.
Like telling one's structure its own size to pass through a void * pointer to some Win32 function.
Messaging can be quite confusing, too: Mixing C++ objects with Win32 windows lead to very interesting examples of Chicken or Egg problem (funny moments when you write a kind of delete this ; in a class method).
Having to subclass a WinProc when you're more familiar with object inheritance is head-splitting and less than optimal.
And of course, there is the joy of "Why in this fracking world they did this thing this way ??" moments when you strike your keyboard with your head once too many and get back home with keys engraved in your forehead, just because someone thought it more logical to write an API to enable the changing of the color of a "Window", not by changing one of its properties, but by asking it to its parent window.
etc.
In the last hand (three hands ???), consider that some people working with legacy APIs are themselves using legacy code styling. The moment you hear "const is for dummies" or "I don't use namespaces because they decrease the runtime speed", or the even better "Hey, who needs C++? I code in my own brand of object-oriented C!!!" (No kidding... In a professional environment, and the result was quite a sight...), you'll feel the kind of dread only condemned feel in front of the guillotine.
So... All in all, it's an interesting experience.
Edit
After re-reading this post, I see it could be seen as overly negative. It is not.
It is sometimes interesting (as well as frustrating) to know how the things work under the hood. You'll understand that, despite enormous (impossible?) constraints, the Win32 API team did wonderful work to be sure everything, from you "olde Win16 program" to your "last Win64 over-the-top application", can work together, in the past, now, and in the future.
The question is: Do you really want to?
Because spending weeks to do things that could be done (and done better) in other more high-level and/or object-oriented API can be quite de-motivational (real life experience: 3 weeks for Win API, against 4 hours in three other languages and/or libraries).
Anyway, you'll find Raymond Chen's Blog very interesting because of his insider's view on both Win API and its evolution through the years:
https://blogs.msdn.microsoft.com/oldnewthing/
Absolutely. When nobody knows the low level, who will update and write the high level languages? Also, when you understand the low level stuff, you can write more efficient code in a higher level language, and also debug more efficiently.
The native APIs are the "real" operating system APIs. The .NET library is (with few exceptions) nothing more than a fancy wrapper around them. So yes, I'd say that anybody who can understand .NET with all its complexity, can understand relatively mundane things like talking to the API without the benefit of a middle-man.
Just try to do DLL Injection from managed code. It can't be done. You will be forced to write native code for this, for windowing tweaks, for real subclassing, and a dozen other things.
So yes: you should (must) know both.
Edit: even if you plan to use P/Invoke.
On the assumption that you're building apps targeted at Windows:
it can sure be informative to understand lower levels of the system - how they work, how your code interacts with them (even if only indirectly), and where you have additional options that aren't available in the higher-level abstractions
there are times when your code might not be as efficient, high-performance or precise enough for your requirements
However, in more and more cases, folks like us (who never learned "unmanaged coding") will be able to pull off the programming we're trying to do without "learning" Win32.
Further, there's plenty of sites that provide working samples, code fragments and even fully-functional source code that you can "leverage" (borrow, plagiarize - but check that you're complying with any re-use license or copyright!) to fill in any gaps that aren't handled by the .NET framework class libraries (or the libraries that you can download or license).
If you can pull off the feats you need without messing around in Win32, and you're doing a good job of developing well-formed, readable managed code, then I'd say mastering .NET would be a better choice than spreading yourself thin over two very different environments.
If you frequently need to leverage those features of Windows that haven't received good Framework class library coverage, then by all means, learn the skills you need.
I've personally spent far too much time worrying about the "other areas" of coding that I'm supposed to understand to produce "good programs", but there's plenty of masochists out there that think everyone's needs and desires are like their own. Misery loves company. :)
On the assumption that you're building apps for the "Web 2.0" world, or that would be just as useful/beneficial to *NIX & MacOS users:
Stick with languages and compilers that target as many cross-platform environments as possible.
pure .NET in Visual Studio is better than Win32 obviously, but developing against the MONO libraries, perhaps using the Sharp Develop IDE, is probably an even better approach.
you could also spend your time learning Java, and those skills would transfer very well to C# programming (plus the Java code would theoretically run on any platform with the matching JRE). I've heard it said that Java is more like "write once, debug everywhere", but that's probably as true as (or even moreso than) C#.
Analogy: If you build cars for a living (programming), then its very pertinent to know how the engine works (Win32).
Simple answer, YES.
This is the answer to any question that is like.. "does it make sense to learn a low level language/api X even when a higher level language/api Y is there"
YES
You are able to boot up your Windows PC (or any other OS) and ask this question in SO because a couple of guys in Microsoft wrote 16-bit assembly code that loads your OS.
Your browser works because someone wrote an OS kernel in C that serves all your browser's requests.
It goes all the way up to scripting languages.
Big or small, there is always a market and opportunity to write something in any level of abstraction. You just have to like it and fit in the right job.
No api/language at any level of abstraction is irrelevent unless there is a better one competing at the same level.
Another way of looking at it: A good example from one of Michael Abrash's book: A C programmer was given the task of writing a function to clear the screen. Since C was a better (higher level) abstraction over assembly and all, the programmer only knew C and knew it well. He did his best - he moved the cursor to each location on the screen and cleared the character there. He optimized the loop and made sure it ran as fast as it could. But still it was slow... until some guy came in and said there was some BIOS/VGA instruction or something that could clear the screen instantly.
It always helps to know what you are walking on.
Yes, for a few reasons:
1) .net wraps Win32 code. .net is usually a superior system to code against, but having some knowledge of the underlying Win32 layer (oops, WinAPI now that there is 64-bit code too) bolsters your knowledge of what is really happening.
2) in this economy, it is better to have some advantages over the other guy when you are looking for a job. Some WinAPI experience may provide this for you.
3) some system aspects are not available through the .net framework yet, and if you want to access those features you will need to use p/invoke (see http://www.pinvoke.net for some help there). Having at least a smattering of WinAPI experience will make your p/invoke development effort a lot more efficient.
4) (added) Now that Win8 has been around for awhile, it is still built on top of the WinAPI. iOS, Android, OS/X, and Linux are all out there, but the WinAPI will still be out there for many many years.
Learning a new programming language or technology is for one of three reasons:
1. Need: you're starting a project for building a web application and you don't know anything about ASP.NET
2. Enthusiasm: you're very excited about ASP.NET MVC. why not try that?
3. Free time: but who has that anyway.
The best reason to learn something new is Need. If you need to do something that the .NET framework can't do (like performance for example) then WinAPI is your solution. Until then we keep ourself busy with learning about .NET
For most needs on the desktop you wont need to know the Win32, however there is a LOT of Win32 not in .NET, but it is in the outlaying stuff that may end up being less than 1% of your application.
USB support, HID support, Windows Media Foundation just off the top of my head. There are many cool Vista API's only available from Win32.
You will do yourself a large favor by learning how to do interop with a Win32 API, if you do desktop programing, because when you do need to call Win32, and you will, you won't spend weeks scratching your head.
Personally I don't really like the Win32 API but there's value in learning it as the API will allow more control and efficiency using the GUI than a language like Visual Basic, and I believe that if you're going to make a living writing software you should know the API even if you don't use it directly. This is for reasons similar to the reasons it's good to learn C, like how a strcpy takes more time than copying an integer, or why you should use pointers to arrays as function parameters instead of arrays by value.
Learning C or a lower level language can definitely be useful. However, I don't see any obvious advantage in using the unmanaged WinAPI.
I've seen low level Windows API code... it ain't pretty... I wish I could unlearn it. I think it benefits to learn low level as in C, as you gain a better understanding of the hardware architecture and how all that stuff works. Learning old Windows API... I think that stuff can be left to the people at Microsoft who may need to learn it to build higher level languages and API... they built it, let them suffer with it ;-)
However, if you happen to find a situation where you feel you just can't do what you need to do in a higher level language (few and far between), then perhaps start the dangerous dive into that world.
yes. take a look at uTorrent, an amazing piece of software efficiency. Half of it's small size is due to the fact that much of it's core components were re-written to not use gargatuian libraries.
Much of this couldn't be done without understanding how these libraries interface with the lower level API's
It's important to know what is available with the Windows API. I don't think you need to crank out code with it, but you should know how it works. The .NET Framework contains a lot of functionality, but it doesn't provide managed code equivalents for the entire Windows API. Sometimes you have to get a bit closer to the metal, and knowing what's down there and how it behaves will give you a better understanding of how to use it.
This is really the same as the question, should I learn a low level language like C (or even assembler).
Coding in it is certainly slower (though of course the result is much faster), but its true advantage is you gain an insight into what is happening at close to the system level, rather than than just understanding someone else's metaphor for what is going on.
It can also be better when things won't work well, or fast enough or with the sort of granularity that you need. (And do at least some subclassing and superclassing.)
I'll put it this way. I don't like programming to the Win32 API. It can be a pain compared to managed code. BUT, I'm glad I know it because I can write programs that otherwise I wouldn't be able to. I can write programs that other people can't. Plus it gives you more insight into what your managed code is doing behind the scenes.
The amount of value you get out of learning the Win32 API, (aside from the sorts of general insights you get from learning about how the nuts and bolts of the machine fit together) depends on what you're trying to achieve. A lot of the Win32 API has been wrapped nicely in .NET library classes, but not all of it. If for instance you're looking to do some serious audio programming, that portion of the Win32 API would be an excellent subject of study because only the most basic of operations are available from .NET classes. Last I checked even the managed DirectX DirectSound library was awful.
At the risk of shameless self-promotion....
I just came across a situation where the Win32 API was my only option. I want to have different tooltips on each item in a listbox. I wrote up how I did it on this question.
Even in very very high level languages you still make use of the API. Why? Well not every aspect of the API has been replicated by the various libraries, frameworks, etc. You need to learn the API for as long as you will need the API to accomplish what you are trying to do. (And no longer.)
Apart from some very special cases when you need direct access to APIs, I would say NO.
There is considerable time and effort required to learn to implement the native API calls correctly and the returning value is just not worth it. I would rather spend the time learning some new hot technology or framework that will make your life easier and programming less painful. Not decades-old obsolete COM libraries that nobody really uses anymore (sorry to COM users).
Please don't stone me for this view. I know a lot of engineers here have really curious souls and there is nothing wrong with learning how things work. Curiousity is good and really helps understanding. But from a managerial point of view, I would rather spend a week learning how to develop Android apps than how to calls OLEs or COMs.
If you planning to develop a cross platform application, If you use win32, then your application could easily run on linux through WINE. This results in a highly maintainable application. This is one of the advantages of learning win32.