Deepsea Obfuscator — V4 Unpack

DeepSea Obfuscator v4 can typically be unpacked and deobfuscated using the open-source tool de4dot, which supports string decryption and removing proxy calls . For advanced, virtualized versions, a memory dumper may be required before applying de4dot to restore the .NET assembly . For a video demonstration of this process, visit YouTube. AI responses may include mistakes. Learn more

I notice you're asking about "DeepSea Obfuscator v4 unpack" — specifically looking for the unpacking feature of this obfuscator.

Here's a concise breakdown:

Phase 4: Manual CFG Repair in dnSpy

After de4dot, open the output in dnSpy. You will notice:

  • Thousands of switch (num) constructs.
  • Locals named V_0, V_1.
  • Calls to Class456.smethod_1001() (VM entry points).

How to flatten the VM:

  1. Find a method that looks like: 
    int num = 0;
while (true)
switch (num)
case 0: ... num = 1; break;
        case 1: ... num = 2; break;
  2. This is the residual VM dispatcher. Use the "Analyze" tool in dnSpy to trace all jump targets.
  3. Manually reorder the cases: Identify which case leads to which based on the num assignments.
  4. Use ILSpy’s "Control Flow Decompilation" plugin if available – but for DeepSea v4, manual correction for critical methods (like license validation) is often faster.

Part 2: Prerequisites for Unpacking

Trying to unpack DeepSea v4 with only dnSpy will lead to an infinite loop of crashes. You need the right tools:

  • x64dbg (with ScyllaHide plugin) – For observing native stub behavior.
  • dnSpy Extensions (or ILSpy with BAML addons) – For managed analysis.
  • ExtremeDumper – For anti-anti-dump memory scraping.
  • Process Hacker 2 – To suspend the Guardian thread.
  • de4dot (cecil-based modded version – the official one does not work on v4).

Method A: The Memory Dump (Standard Procedure)

This is the most reliable method for DeepSea v4. deepsea obfuscator v4 unpack

  1. Run the Target: Execute the protected application. If it is a "Native Wrapper," you will see a standard process in Task Manager.
  2. Attach Debugger/Dumper:
    • Open MegaDumper or ExtremeDumper.
    • Select the running process.
    • These tools scan the process memory for loaded .NET Assembly structures.
  3. Dump the Assembly:
    • The tool will identify the embedded .NET module (usually named something random or the original name).
    • Click "Dump." This saves the module from RAM to disk.
  4. Fix the Dump:
    • Dumped files often have "corrupted" headers because they were dumped from memory.
    • Open the dumped file in de4dot: de4dot.exe dumped_file.dll
    • De4dot will automatically detect DeepSea, decrypt the strings, remove control flow obfuscation, and fix the metadata.
    • Save the cleaned file.

If you're analyzing a protected sample:

  • Tools like de4dot (community-driven) have partial support for older DeepSea versions
  • v4 likely requires manual unpacking: break on module load, dump from memory after deobfuscation routines run
  • Common approach: debug with dnSpy, find the entry point where runtime decryption occurs, dump after methods are restored

B. String Encryption

DeepSea v4 implements aggressive string encryption.

  • Mechanism: All user-strings (error messages, URLs, passwords) are replaced with a byte array or a gibberish string.
  • Runtime: At runtime, a decryptor method is called to resolve the string.
  • Identification: You will typically see a static method (often with a randomized name) called frequently throughout the code, accepting an int or string and returning the valid string.