# Reversing

## Wasm decompiler

[https://www.pnfsoftware.com/jeb/demowasm](https://www.pnfsoftware.com/jeb/demowasm)

## .Net decompiler

[https://github.com/icsharpcode/ILSpy](https://github.com/icsharpcode/ILSpy)  
[ILSpy plugin for Visual Studio Code](https://github.com/icsharpcode/ilspy-vscode): You can have it in any OS \(you can install it directly from VSCode, no need to download the git. Click on **Extensions** and **search ILSpy**\).  
If you need to **decompile**, **modify** and **recompile** again you can use: [**https://github.com/0xd4d/dnSpy/releases**](https://github.com/0xd4d/dnSpy/releases) \(**Right Click -> Modify Method** to change something inside a function\).

### DNSpy Logging

In order to make **DNSpy log some information in a file**, you could use this .Net lines:

```bash
using System.IO;
path = "C:\\inetpub\\temp\\MyTest2.txt";
File.AppendAllText(path, "Password: " + password + "\n");
```

### DNSpy Debugging

In order to debug code using DNSpy you need to:

First, change the **Assembly attributes** related to **debugging**:

![](../.gitbook/assets/image%20%287%29.png)

From:

```aspnet
[assembly: Debuggable(DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints)]
```

To:

```text
[assembly: Debuggable(DebuggableAttribute.DebuggingModes.Default |
DebuggableAttribute.DebuggingModes.DisableOptimizations |
DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints |
DebuggableAttribute.DebuggingModes.EnableEditAndContinue)]
```

And click on **compile**:

![](../.gitbook/assets/image%20%28144%29.png)

Then save the new file on _**File >> Save module...**_:

![](../.gitbook/assets/image%20%28261%29.png)

This is necessary because if you don't do this, at **runtime** several **optimisations** will be applied to the code and it could be possible that while debugging a **break-point is never hit** or some **variables don't exist**.

Then, if your .Net application is being **run** by **IIS** you can **restart** it with:

```text
iisreset /noforce
```

Then, in order to start debugging you should close all the opened files and inside the **Debug Tab** select **Attach to Process...**:

![](../.gitbook/assets/image%20%28166%29.png)

Then select **w3wp.exe** to attach to the **IIS server** and click **attach**:

![](../.gitbook/assets/image%20%28274%29.png)

Now that we are debugging the process, it's time to stop it and load all the modules. First click on _Debug >> Break All_ and then click on _**Debug >> Windows >> Modules**_:

![](../.gitbook/assets/image%20%28210%29.png)

![](../.gitbook/assets/image%20%28341%29.png)

Click any module on **Modules** and selec**t Open All Modules**:

![](../.gitbook/assets/image%20%28216%29.png)

Right click any module in **Assembly Explorer** and click **Sort Assemblies**:

![](../.gitbook/assets/image%20%28130%29.png)

## Java decompiler

[https://github.com/skylot/jadx](https://github.com/skylot/jadx)  
[https://github.com/java-decompiler/jd-gui/releases](https://github.com/java-decompiler/jd-gui/releases)

## Debugging DLLs

### Using IDA

* **Load rundll32** \(64bits in C:\Windows\System32\rundll32.exe and 32 bits in C:\Windows\SysWOW64\rundll32.exe\)
* Select **Windbg** debugger
* Select "**Suspend on library load/unload**"

![](../.gitbook/assets/image%20%2869%29.png)

* Configure the **parameters** of the execution putting the **path to the DLL** and the function that you want to call:

![](../.gitbook/assets/image%20%28325%29.png)

Then, when you start debugging **the execution will be stopped when each DLL is loaded**, then, when rundll32 load your DLL the execution will be stopped.

But, how can you get to the code of the DLL that was lodaded? Using this method, I don't know how.

### Using x64dbg/x32dbg

* **Load rundll32** \(64bits in C:\Windows\System32\rundll32.exe and 32 bits in C:\Windows\SysWOW64\rundll32.exe\)
* **Change the Command Line** \( _File --> Change Command Line_ \) and set the path of the dll and the function that you want to call, for example: "C:\Windows\SysWOW64\rundll32.exe" "Z:\shared\Cybercamp\rev2\\14.ridii\_2.dll",DLLMain
* Change _Options --> Settings_ and select "**DLL Entry**".
* Then **start the execution**, the debugger will stop at each dll main, at some point you will **stop in the dll Entry of your dll**. From there, just search for the points where you want to put a breakpoint.

Notice that when the execution is stopped by any reason in win64dbg you can see **in which code you are** looking in the **top of the win64dbg window**:

![](../.gitbook/assets/image%20%28181%29.png)

Then, looking to this ca see when the execution was stopped in the dll you want to debug.

## ARM & MIPS

{% embed url="https://github.com/nongiach/arm\_now" %}

## Shellcodes

You should try ****[**scdbg**](http://sandsprite.com/blogs/index.php?uid=7&pid=152).  
It will tell you things like **which functions** is the shellcode using and if the shellcode is **decoding** itself in memory.

```bash
scdbg.exe -f shellcode # Get info
scdbg.exe -f shellcode -r #Run it
scdbg.exe -f shellcode -r #Run it with hooks
scdbg.exe -f shellcode -d #Dump decoded shellcode
scdbg.exe -f shellcode /findsc #Find offset where starts
```

To **run a shellcode** you can also use: [http://mcdermottcybersecurity.com/articles/windows-x64-shellcode\#testing](http://mcdermottcybersecurity.com/articles/windows-x64-shellcode#testing)

## [Movfuscator](https://github.com/xoreaxeaxeax/movfuscator)

This ofuscator change all the instructions for `mov`\(yeah, really cool\). It also uses interruptions to change executions flows. For more information about how does it works:

* [https://www.youtube.com/watch?v=2VF\_wPkiBJY](https://www.youtube.com/watch?v=2VF_wPkiBJY)
* [https://github.com/xoreaxeaxeax/movfuscator/blob/master/slides/domas\_2015\_the\_movfuscator.pdf](https://github.com/xoreaxeaxeax/movfuscator/blob/master/slides/domas_2015_the_movfuscator.pdf)

If you are lucky [demovfuscator ](https://github.com/kirschju/demovfuscator)will deofuscate the binary. It has several dependencies

```text
apt-get install libcapstone-dev
apt-get install libz3-dev
```

And [install keystone](https://github.com/keystone-engine/keystone/blob/master/docs/COMPILE-NIX.md) \(`apt-get install cmake; mkdir build; cd build; ../make-share.sh; make install`\)

If you are playing a **CTF, this workaround to find the flag** could be very useful: [https://dustri.org/b/defeating-the-recons-movfuscator-crackme.html](https://dustri.org/b/defeating-the-recons-movfuscator-crackme.html) 

## Courses

* [https://github.com/0xZ0F/Z0FCourse\_ReverseEngineering](https://github.com/0xZ0F/Z0FCourse_ReverseEngineering)
* [https://github.com/malrev/ABD](https://github.com/malrev/ABD) \(Binary deobfuscation\)