DNGuard HVM v3.953

[Mohd]

View File

DNGuard HVM v3.953

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Try to unpack or alternatively provide the secret key, URL, Name and Address 

Protections used:

DNGuard Enterprice HVM 3.953

 

Good luck.

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• Submitter
  Mohd
• Submitted
  09/08/2020
• Category
  UnPackMe (.NET)

 

[Washi]

Since the challenge description allows it, I'm going for the quick serial fish for now

Spoiler

Secret Key: AWX610881RFFJSDJSZV
URL: http://localhost:52735/
Vendor: Fadi Sami Khalid
Address: Jordan - Amman - Khalda

Approach:

Spoiler

Obfuscation does not really matter if your methods are just simple string comparisons. The x86 generated by the JIT compiler still reveals everything

• Run app, enter random stuff in textboxes, press Validate to trigger the JIT compiler to compile the validation method. Notice text of the label changes to Not Correct.
• Attach WinDbg, set breakpoint on Control.set_Text (use !name2ee System.Windows.Forms.dll System.Windows.Control.set_Text to get the address to breakpoint). Continue execution and press Validate again.
• Type !clrstack to notice the click handler is in Form1._01.01.  Copy the address of the handler and dump the x86 code using !U <address>. (dump here https://pastebin.com/br3s09Gv)
• Notice in x86 code its just a bunch of string.Equals calls. Set a breakpoint on all string.Equals(string, string) calls in the method. Continue execution and press Validate one more time again.
• Use !dumpstackobjects to read out the correct values for every one of these calls.

 

Edited September 9, 2020 by Washi

[AzoresRCE]

I would just like to point out that this is DNGuard Enterprise HVM 3.9.5.1 not 3.9.5.3

Edited September 10, 2020 by AzoresRCE

[0x59]

Test_App_-_Full_-_End_Encrptoin-Unpacked.rar

--Not unpacked by me--

Hook jit and after use dng hvm unpacker by @CodeExplorer just update anti-eh anti-eh2 anti-jit 

Open hvmruntime.dll on ghidra and go to Export/VMRuntime and start analysing it 

Edited January 5, 2021 by 0x59

[GautamGreat]

On 1/4/2021 at 3:02 AM, 0x59 said:

Test_App_-_Full_-_End_Encrptoin-Unpacked.rar

--Not unpacked by me--

Hook jit and after use dng hvm unpacker by @CodeExplorer just update anti-eh anti-eh2 anti-jit 

Tell me if u need more info 

I would love to have some information about hooking Jit

[0x59]

5 hours ago, GautamGreat said:

I would love to have some information about hooking Jit

just dm me sir 

[BlackHat]

How to Unpack ?

Spoiler

1. You need to Hook the JIT Code at Runtime by executing the file.
2. Now Detect the Method Bodies in JIT and Read it with .Net Libraries, Your main work is to restore the value of Instructions but Here is a catch that Method Tokens are encrypted/locked in HVM Version.
3. You need to Analyze and understand the Runtime.dll to Restore the value.
4. You can Restore the Original and Remove proxy by analyzing the methods after devirting.
5. Strings are also encrypted but just Invoke static string methods in "ZYXDNGuarder" and restore those with Original Value.

Decrypt HVM Token and the Offset Value of HVM Table --> Parse their Structure Schema and Read HVM Table

At Last Read Methods after detecting those and append in your Main Assembly.

 

Solution -

Spoiler

 

3.9.5.3.zip

[GeGe]

确定.zip

[CodeExplorer]

On 9/10/2020 at 12:09 PM, AzoresRCE said:

I would just like to point out that this is DNGuard Enterprise HVM 3.9.5.1 not 3.9.5.3

Sometimes DNGuard author don't change the version number.

Anyway this unpackme require netstandard 2.0 dll, your can get it from
https://www.dllme.com/dll/files/netstandard/c207d3c8d3776e15d2c43fd26ace385c
or attached.
 

Yes @0x59. More info needed.
 

netstandard_x86.zip

[im_nop]

thank u for ur share this reverse tool~