CODEWITHSUNDEEP
c#.netreverse-engineeringdecompilerdotpeek
sk84z
sk84z

Reputation: 313

How to reverse engineer an .exe that uses a .resource file to store an assembly?

Context

I work as a game developer at a studio that develops an MMO. We built an authoritative server but still run into issues with exploits and automation. I downloaded the main bot used to hack our game in an effort to determine how it exploits our server so we can patch accordingly.

Question

I decompiled the .exe using dotPeek to get the source files but ran into an issue: I only got the source files for the launcher. The launcher injects the core assembly into our application at runtime. It does so by storing the assembly as hex data in a .resource file. Any idea of how I can get the source code from this .resource file?

Solution

Thanks for everyone's help. I got the source files by extracting the binary data from the .resource file and writing it to a .dll file and then decompiling it using dotPeek. See my solution for more details.

Upvotes: 1

Views: 4846

Answers (3)

sk84z
sk84z

Reputation: 313

Thanks everyone for the help - a combination of using a decompiler and reading the binary assembly data at runtime and writing it to a .dll file helped me get the source code:

I used dotPeek to decompile the launcher. In assembly explorer, I then right clicked the assembly and selected Export to Project... I then opened the project in Visual Studio and inserted a line that used File.WriteAllBytes to write the the byte[] (already available via their application, but this just got the binary data from the .resource file using ResourceManager.GetObject) to a .dll file. I then opened that .dll file in dotPeek and wala - source code visible.

Upvotes: 1

Davesoft
Davesoft

Reputation: 764

I recommend designing around the problem, a kind of soft-captcha enforced by the server. The truth of your problem is: .Net is open to extension. Rather than engage in a 'cat and mouse arms race' around the client exe, think about how you detect non-human activity, or how to randomly demand human-only activity.

If your game is worth the attention, they will overcome you. They are many :)

Upvotes: 0

Ardowi
Ardowi

Reputation: 59

Shouldn't you be able to use GetManifestResourceStream to get the embedded data?

Upvotes: 2

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