Reversing Tools

Wasm decompiler / Wat compiler

Online:

Use to decompile from wasm (binary) to wat (clear text)
Use to compile from wat to wasm
you can also try to use to decompile

Software:

.Net decompiler

: 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: (Right Click -> Modify Method to change something inside a function). You cloud also try

DNSpy Logging

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

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:

From:

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

To:

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

And click on compile:

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

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:

iisreset /noforce

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

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

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:

Click any module on Modules and select Open All Modules:

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

Java decompiler

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"

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

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:

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

ARM & MIPS

Shellcodes

Debugging a shellcode with blobrunner

Debugging a shellcode with jmp2it

Debugging shellcode using Cutter

Note that Cutter allows you to "Open File" and "Open Shellcode". In my case when I opened the shellcode as a file it decompiled it correctly, but when I opened it as a shellcode it didn't:

In order to start the emulation in the place you want to, set a bp there and apparently cutter will automatically start the emulation from there:

You can see the stack for example inside a hex dump:

Deobfuscating shellcode and getting executed functions

scdbg.exe -f shellcode # Get info
scdbg.exe -f shellcode -r #show analysis report at end of run
scdbg.exe -f shellcode -i -r #enable interactive hooks (file and network) and show analysis report at end of run
scdbg.exe -f shellcode -d #Dump decoded shellcode
scdbg.exe -f shellcode /findsc #Find offset where starts
scdbg.exe -f shellcode /foff 0x0000004D #Start the executing in that offset

scDbg also counts with a graphical launcher where you can select the options you want and execute the shellcode

The Create Dump option will dump the final shellcode if any change is done to the shellcode dynamically in memory (useful to download the decoded shellcode). The start offset can be useful to start the shellcode at a specific offset. The Debug Shell option is useful to debug the shellcode using the scDbg terminal (however I find any of the options explained before better for this matter as you will be able to use Ida or x64dbg).

Disassembling using CyberChef

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:

apt-get install libcapstone-dev
apt-get install libz3-dev

Delphi

Courses

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Last updated 3 years ago