Questions tagged [javascript]

JavaScript or JS is an interpreted computer programming language. It was originally implemented as part of web browsers.

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Frida hook InsertMenuItemW

I'm trying to get information about menu items in an application. Experimentally established that InsertMenuItemW is called. Thanks to the documentation, I set the number of input parameters and wrote ...
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Tool to Analyse Browser memory in Javascript console

By using the Inspector tool, we can access every object in the browser using the console. For example, if you go to Youtube.com and you open the console, and you type ytInitialData , you can see the ...
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How to reverse engineer a web application's authentication method(s)?

For doing security scanning with a tool like Owasp Zap, a common desire is to do an authenticated scan, where one or more test users is logged in, often in an automated fashion. I think different ...
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'... Debugger undefined or null reference' error when WinDBG TTD Scripting with Javascript

I tried Javascript scripting on WinDbg (TTD specifically); but even in simple example I get error Unable to get property 'Debugger' of undefined or null reference. Line was simply var ctl = host....
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How does one go about reverse-engineering obfuscated/minified JavaScript in a browser like you would code in an IDE?

I am trying to figure out how some minified and possible highly-obfuscated JavaScript works. There are thousands of lines spanning multiple JS files. I have had a lot of success debugging it in my ...
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Bypass Javascript Debug Prevention in Firefox

I've looked around, and can't find an answer for my specific question. The closest I could find was this. I'm trying to reverse engineer some suspicious Javascript, but it repeatedly calls a debugger ...
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926 views

Any good places to learn about JS de-obfuscation?

I am trying to make a bot on a specific website, so I have to reverse a lot of JS scripts. The reversing it self is not that hard but the de-obfuscation is. Lots of the scripts are obfuscated with ...
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How to clean obfuscated code from fake if statements?

I am trying to deobfuscate javascript code. Firstly I extracted strings from big array. Then I saw many parts like this There is only one line of code which makes sense. Is there any Node.js cleaner ...
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Confusion about if statement in disassembly

I recently got into reverse engineering applications for fun. Can someone please help me with this if statement. 140005914 75 38 JNZ LAB_14000594e 140005916 48 8b 4 MOV ...
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Disassembly a win Linux file

I have a file that has a compiled assembly code and being loaded into javascript code for execution. How can I “inspect” the file? I am aware of tools like immunity debugger or ollydbg but I am not ...
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4 votes
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Is there a tool to compare javascript files for differences, while also ignoring local identifier changes?

When trying to compare the difference between two minified javascript files with random identifier names, about 95% of the changes are identifiers being renamed. I would like to use a tool that ...
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Methods to alert inappropriate use of JS code

Let's say we have a JS code library that is not for sale, just internal. Of course, anyone who can access the website will be able to download that and reuse it. To avoid others to reuse that library, ...
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automatically find the object "this" refers to in js

Im quite new to javascript and sometimes I find it really hard to find what object a keyword 'this' refers to. Is there a code editor that is able to do that for me? Or any other advice that could ...
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How can I modify or decompile Hermes JS bytecode?

Since React Native 0.60.4 developers can opt-in to use the Hermes JS Engine. This generates an index.android.bundle binary that contains Hermes JS bytecode. The Hermes documentation mentions hbcdump ...
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3 votes
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164 views

Where to start with reversing a custom JavaScript VM?

I have recently ran into the most heavy JavaScript obfuscation I've seen. It is using a custom VM to execute bytecodes. I have never dealt with such obfuscation, and I am wondering where I can start ...
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What browser do during initial web page request?

I am trying to understand why if I do fetch() 4 times on the active web page, after the fifth fetch server returns response that I am a "robot" I am using google chrome I go the following ...
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300 views

How to get video file URL from Twitter

I am looking how to find the video URL of a Twitter video so I can code a converter later (using nodejs or something), but I can't figure out how to do this. I saw this but it doesn't really clear ...
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How to locate the function being applied on password

I am thinking of taking up ethical hacking as a hobby. So, I installed Burp Suite Community Edition and set it up with Firefox. I opened Instagram and tried to login with these details (just for ...
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2 votes
1 answer
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Load a *.dylib or *.so object into the Javascript V8 runtime?

I was reading this Frida release page and noticed it made the following reference: Short of writing the whole agent in C, one could go ahead and build a native library, and load it using Module....
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Intercepting packets from Electron App to keyboard in Linux

I have a USB keyboard which has an Electron app to set the macros on the keyboard. I unpacked the app.asar file, and the JS files seem to indicate that it is a ReactJS app, and is a minified ...
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Trying to replicate encryption of an android app

I was trying to replicate/copy the encryption of an android app which uses CryptoJS with sha256 encryption as having seen in the source code of the android app. fingerprinting the app, it was built ...
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2 answers
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Reverse Engineering Javascript - Out of Memory

I found this javascript file on one of those online movie streaming services and was interested in finding out what it does. However, after trying many deobfuscators I am still stuck. A major ...
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236 views

How to modify JS with mitmproxy?

I am trying to reverse engineer a heavily obfuscated web application, and I would like to modify the JS to add logging. So far, I've set up mitmproxy, but I can't figure out what the best way to edit ...
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De-obfuscate JS code [closed]

I came across a script that converts font files from one type to another (i.e. WOFF to TTF, etc). I would like to understand it and incorporate some of the code into a personal project. The script ...
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1 answer
262 views

Is it possible to completely reverse this code?

i have this code i'm trying to deobfuscate https://pastebin.com/g5mHpWE4 I used https://beautifier.io/ and http://www.jsnice.org/ but the result is still not good, current code: https://pastebin.com/...
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1 answer
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How can I deobfuscate this javascript code

I am trying to deobfuscate this javascript code, but I don't know how it was created. Can you please tell me what the mechanism or the function is that generate such characters in javascript? É=-~-~[]...
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How to hook eval function in node.js

As the eval() function of JavaScript is an evil, I want to hook or monkey-patch eval() function of JavaScript in node.js. I want to intercept all arguments passed in eval() function. Please guide me ...
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1 vote
1 answer
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What's wrong with my mitm to support rr commands with gdbserver on IDA?

First of here is the gdb remote protocol doc. The idea of the below script is the following - you enter an actual command (one that will be send as a direct packet see packets) in the gdb window then ...
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Need help reversing .m4t TTML subtitles format

I am currently trying to create subtitles for some proprietary Sony software. Unfortunatly, it only recognizes Sony's own .m4t subtitles format. After some research I found that this subtitles is also ...
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Decrypt config.bin file from Huawei B5328 router. I have source files

I need some help in decrypting the file config.bin generated by the page backup_setting.html from Huawei B5328 router. I have access to all files in the router, even the www files hosted on the www ...
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How to programmatically add HTML DOM breakpoints in chromium?

I've seen from this post about Chromium DevTools that there exists the possibility to add DOM breakpoints. Given that I've a full range of elements to monitor I was trying to find a way to ...
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2 votes
1 answer
865 views

De-obfuscating code ran through JScrambler 3x via Eval() functions

I am relatively new to JS and de-obfuscation in general and I am having difficulties reversing some complicated JS. I know the code itself is obsfucated via jscrambler 3-4x and therefore is ran ...
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1 vote
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132 views

deobfuscating/decompiling extremely complicated javascript [closed]

I am working with some extremely complicated JavaScript. It is around 70,000 lines long and sections of the code look like this U2xx.l11="0x78920d50";m2xx.r9G="11";b2xx.v3y="0x744ebc37";P2xx.K5h="...
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javascript hook comparisons

Look at this very basic javascript code: if (s=='abcd') { if (s2='cdef') { ... } } I want to hook all tests: I want to get this: (s,'==','abcd') (s2,'==','cdef') Is there a way ...
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1 answer
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WebSocket debugging in Javascript app gives "401 Unauthorized" [closed]

I'm attempting to reverse engineer a private API used by an Android app that makes use of WebSockets. These requests are made from JavaScript inside a WebView. I use Charles to intercept both HTTP ...
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1 vote
2 answers
3k views

How to copy video address from tweet?

Twitter has an option to right-click on a video and "copy video address" but this button seems to be broken as it doesn't copy anything to the clipboard, even after I disable Ghostery/adblock. I ...
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Is v8's --print-bytecode safe?

I just saw this post, and I was wondering if it's safe to get v8 bytecode in that fashion with --print-bytecode.
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1 vote
1 answer
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Analyzing and deobfuscating complex JS code [duplicate]

I am looking to reverse engineer a very ugly piece of JS found here. As far as I can tell, this script generates and sets some cookies on my browser that identify it on the site. Deobfuscating it ...
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1 vote
1 answer
923 views

How do you un-obfuscate JS code that is evaluating your browser environment?

Given this: <script>var _0x4c36=['w6rChcKeWsKXw7TCocOlNF8Kw7bCuMKdKsOWTMKjF2A=','V3PClhXDu8OCCMO5WwbCp8KhD8KVw7LDo8KOwr7CiA==','w6saBzVaIwbDk8OqHMKGwpvDgzzCixMTMMOL','...
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1 vote
2 answers
170 views

How can a Javascript file drop .exe written in Visual Basic without network communication?

I am analyzing a malicious JS file, which is obfuscated in a way that I could not de-obfuscate. When I executed it in a virtual machine and spectated process changes, I noticed that a new executable ...
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4 votes
3 answers
315 views

Obfuscated code analysis - can unused variables be ignored?

I am analyzing a malicious javascript. The code is encoded and obfuscated in a way that I did not manage to even partially deobfuscate yet and it is filled with long strings. In order to simplify the ...
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1 vote
1 answer
4k views

Is deobfuscation of my javascript code hard or easy?

I am trying to protect my app code from theft. Since most of it is written in javascript I had to use many obfuscation techniques to make it incomprehensible. I have written a very small piece of ...
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-2 votes
1 answer
16k views

How do I decode this JavaScript code? [duplicate]

Each file starts with the same function: (function(_0x128f83, _0x1ae5b9) { var _0x1b5471 = function(_0x339be5) { while (--_0x339be5) { _0x128f83['push'](_0x128f83['shift']()); ...
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How decrypt hexadecimal javascript code? [closed]

Someone here already had success to deobfuscate 100% a "hexadecimal" Javascript code? E.g.: var _0x22bc92 = function() { var _0x26938d = !![]; return function(_0x100751, _0x54d399) { ...
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Movies Anywhere ID?

I'm looking to automate requesting movies from different retailers on Movies Anywhere. The URL for the request is: https://retailer.moviesanywhere.com/api/purchase/initiate?retailer={retailer}&id={...
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1 vote
1 answer
731 views

Map an obfuscated javascript file to the original

Among other approaches, there are ways to "prettify" obfuscated javascript. But most of such approaches are geared towards someone trying to understand code that's not their own (e.g. from a website, ...
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What is the link between g-recaptcha-response one time token and deciphered audio text?

They are multiple reports of recaptcha v2 bypass. Most of the time, the explanation is neural networks services provided by Google or ɪʙᴍ. But there is something I am failing to understand : for most ...
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-2 votes
1 answer
774 views

would be possible to deobfuscate javascript code? [closed]

the code is: https://pastebin.com/wTkB81v4 would be possible to deobfuscate the code to get the original code?
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1 vote
1 answer
349 views

deobfuscating javascript injected into Wordpress

Found a WP site (not mine) with lovely obfuscated code injected into the footer so I've been trying to de-obfuscate it. I ran it through unpacker, then converted hex to ASCII, then un-minified to ...
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1 vote
2 answers
936 views

IDA Pro Alternative for JavaScript?

I am looking for a good "disassembler" for JavaScript, like IDA Pro but for JS. I am looking at a chrome extension, but the JavaScript is heavily obfuscated. After deobfuscating, I am left with ...
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