CODEWITHSUNDEEP
visual-studiodebuggingvisual-studio-debugging
RenniePet
RenniePet

Reputation: 11658

Visual Studio: No disassembly available

I want to run the Visual Studio debugger on a .Net program that has been obfuscated. (It's my own program - I'm not trying to crack someone else's program.)

When I compile the program with "System.Diagnostics.Debugger.Break()", or if I attach the debugger to the running process, then the debugger shows "No Source Available". This I understand - there is no source that corresponds to the obfuscated version of the program. But when I click "Show Disassembly" it shows a Disassembly window with "No disassembly available."

Why? Any suggestions as to what I can do to get the disassembly to work?

Under Debug Options I do have "Enable address-level debugging" and "Show disassembly if source is not available" checked.

Thanks.

EDIT

Just to try to explain a bit more ...

The program in question is my own program, and the obfuscation program being used is also my own program. The obfuscation program runs ILDAsm.exe, modifies the ILAsm code, and runs ILAsm.exe.

My obfuscation is apparently introducing problems so the program no longer works correctly. To understand how/why it isn't working I'd like to trace it. But for some reason Visual Studio debugger says "No disassembly available", and then I can't do anything at all. (When the non-obfuscated program is run under Visual Studio the Disassembly window can be opened and shows the expected information. It's only the obfuscated version that produces this problem with VS debugger.)

EDIT 2

Haven't been able to find an answer to my question, but I do have a sort of workaround now.

I've installed WinDbg and confirmed that it can attach to my obfuscated program and can at least single-step it and show the current execution location in a disassembly window. But I've never used WinDbg before, and it looks a bit daunting.

I've also followed the advice seen several places to load sos.dll into WinDbg. Maybe that will help.

But I'm guessing that what I'll actually end up doing is throwing lots of temporary logging statements into my program around the places where it's not working, and hopefully gain some understanding that way.

Upvotes: 4

Views: 8142

Answers (1)

RenniePet
RenniePet

Reputation: 11658

OK, I happened to stumble on what I was doing wrong.

As I mention in the first edit of my question, my obfuscation is being done by running ILDAsm.exe, modifying the ILAsm statements, and then running ILAsm.exe. It turns out I was missing the /Debug option on the ILAsm.exe run. So even though my Visual Studio builds were Debug builds, the JIT conversions at run time were Release/Optimize conversions.

With /Debug specified on ILAsm.exe I'm getting a PDB file, and when Visual Studio debugger connects to my program I'm getting IL source code display and, if I request it, disassembly display too! So now all is well!

Upvotes: 4

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