Javascript+deobfuscator+and+unpacker+portable -

| Tool | Command / Notes | |------|----------------| | de4js CLI | npx de4js or download de4js.js – runs on Node.js, portable | | jstools | unpack.js – classic unpacker for eval(function(p,a,c,k,e,d)...) | | js-beautify | npx js-beautify obfuscated.js – not deobfuscation, but essential first step | | ast-grep / ts-morph scripts | Write your own portable unpacker for custom packers |

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After unpacking, the AST is normalized:

For nested eval or Function constructors, static analysis is insufficient. A lightweight JS sandbox is implemented using either:

The sandbox intercepts:

class PortableSandbox {
  constructor(code, timeoutMs = 1000) 
    this.code = code;
    this.timeout = timeoutMs;
run() {
    const captured = [];
    const safeGlobal = new Proxy({}, {
      get(target, prop) {
        if (prop === 'eval') return (c) => captured.push(c);
        if (prop === 'Function') return (...args) => captured.push(args.pop());
        return () => {};
      }
    });
    // Execute with restricted globals
    const fn = new Function('window', 'self', 'global', this.code);
    try  fn(safeGlobal, safeGlobal, safeGlobal);  catch(e) {}
    return captured;
  }
}

Why is portability a non-negotiable feature for this class of tool? Traditional deobfuscation methods often rely on online web services or heavy Integrated Development Environments (IDEs). However, these solutions carry significant risks and limitations.

First, analyzing malicious code in a cloud-based service is dangerous. Uploading an unknown, potentially malicious script to a third-party website risks data leakage. The analyst cannot know if the service logs submissions, shares them with adversaries, or even if the service itself is compromised. A portable tool—one that runs entirely on a local machine from a USB drive or a standalone executable—ensures that the code never leaves the analyst's controlled environment.

Second, portability enables air-gapped and incident response workflows. In high-security environments (e.g., financial institutions, government agencies, or forensic labs), internet access may be restricted. An online deobfuscator is useless in a quarantined virtual machine or a network cut off from the web. A portable, offline tool is the only viable solution for dissecting code on a compromised host without alerting a potential attacker. javascript+deobfuscator+and+unpacker+portable

Third, speed and repeatability are enhanced. A portable tool has no network latency. It can be scripted, integrated into automated malware analysis pipelines, and shared as part of a forensic toolkit without installation overhead.

For professionals, a single tool is rarely enough. You need a suite. Create a folder on a USB drive called JS_Deobfuscator_Portable with this structure:

JS_Deobfuscator_Portable/
├── de4js.html
├── CyberChef.html
├── unpacker.exe
├── portable_python/
│   ├── python.exe
│   ├── p42.py
│   └── libs/
├── beautify.js (a Node script run via portable Node)
└── README.txt (documentation for your team)

Add a simple batch script unpack.bat:

@echo off
echo Drag and drop a JS file onto this window:
set /p inputfile=
echo Running unpacker...
unpacker.exe %inputfile% output_clean.js
echo Done. Check output_clean.js
pause

Now, you have a portable forensics workstation that fits in your pocket.

| Metric | JSDeob-Port | de4js | jsnice | |----------------------------|-------------|-------|--------| | Unpacking success (nested) | 94.2% | 61.5% | 72.3% | | Semantic accuracy | 91.7% | 83.2% | 79.4% | | False positive rate | 2.1% | 8.4% | 5.7% | | Avg time per sample (ms) | 127 | 340 | 890 |

Notable failure cases (5.8%):