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Questions tagged [byte-code]

Assembler-like language destined to be executed in an interpreter, in a virtual machine or by just in time compilation. Java, Python and many other high-level languages are using bytecode languages.

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1answer
47 views

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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1answer
100 views

Java digital signature

I'm using a java application & it validates two parameters from web server one is "signature" & another one is 'id". <signature>...
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0answers
27 views

Interrupt a java thread after some specified time

Recently, I faced a problem in java bytecode editing. I would like to put this application startup thread into sleep or interrupt it after some specified time.
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0answers
48 views

How to reverse a java thread to get its origin

I was working on a java application which is run for the first couple of minutes & then application interface hangs. I had open the application in JMC & it shows later I create a thread dump ...
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2answers
466 views

Patching a class file inside Jar using bytecode

I was trying to patch an application, but the application is required to exact same class size as the original one but editing class file with JByteMod, Recaf or whatsoever always changes the class ...
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1answer
104 views

Disassemble/decompile arbitrary JVM bytecode

I have an obfuscated java binary which does runtime code injection using java reflection like this. Object o = "a long string"; ((Method)o).invoke(params..); (If I write this in a java file, it ...
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2answers
350 views

verifyError in youtube android app modification

I try to decompile youtube android application and modify it but when I build the application and install on a virtual device faced with below error: E/AndroidRuntime(1782): java.lang.VerifyError: ...
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1answer
126 views

How add String.equals to java bytecode (Krakatau)

I use Krakatau to edit java code. class test{ public boolean Func2(String text) { if(text=="aaaaaa") return true; return false; } } When I compile it I get this java bytecode ....
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1answer
220 views

Compute stack frames while edit java bytecode

I saw here edit java bytecode got error that when editing java bytecode with Krakatau ,it may happend to error on stack frames. The answer there offer to change Krakatau version to 50. If I only ...
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0answers
73 views

edit java bytecode got error

I have a java application with a lot of .class files. I edited one function at a class file and added a few lines but got an error. I added those lines: aload 1 (load argument 1 to stack) ldc_w "...
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1answer
267 views

explain java bytecode

I saw java bytecode that need to compare to var, if they equal return true, else ..... if(var1==var2) return true; else { ...} on bytecode aload 1 aload 2 if_acmpne 6 iconst 1 ireturn I ...
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1answer
306 views

can't edit class file with recaf.0.9 without re-compile

I have this java code public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } I compile to class file, run it , and all fine. I ...
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1answer
115 views

[B symbol in java bytecode

I looking at java bytecode and understand almost everything. I saw the symbol [B on java bytecode. What does it mean?
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1answer
121 views

I'm would like to view this malicious payload, but am having trouble decoding it

This is a gzip compressed base64 string. I tried decoding it with an online converter but it said the data was corrupt. Can anyone decode this? H4sIAAAAAAAAAL1X6W6jyBb+...
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1answer
53 views

Need help understanding “garbage” data in https request

I managed to overcome certificate pinning in an android application and I am now able to view all the HTTPS request in plain text. However, I came across this request that I still do not understand: ...
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1answer
527 views

How to assemble back a disassembled ChunkSpy LUA?

Is it possible to assemble back the ChunkSpy's dissembled LUA files? Here's an example: 0B50 05000000 [001] getglobal 0 0 ; script 0B54 C63E0000 [002] gettable 0 0 ...
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0answers
92 views

Where are the stack windows when debugging Java bytecode with Bytecode Visualizer?

I have an obfuscated .Jar file and I want to debug it. I tried debugging it with Eclipse's Bytecode Visualizer: But when debugging, I don't see stack windows. Where can I find them?
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1answer
544 views

How do I denote and use JMP /5 in byte code

I'm on the OSX platform working with x86_64. I've worked out how to do near jumps with the E9 byte code directive where my relative addresses have 4 bytes (teamed up with RIP) Now I have an instance ...
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1answer
368 views

Unable to call function with CreateRemoteThread

I am messing around with some dll injection/code injection. Therefore I made a little program which does nothing, but it has a function in it, which never get called and I wrote another program which ...
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0answers
143 views

rebuilding a java application

I wish to rebuild MotiveWave, a charting tool, from its jars. This application has a feature (probably in one of the class files but I don't know which) that i want to build upon. I mean I want to ...
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0answers
172 views

code coverage decompiler / reverse engineering

I'm trying to decompile some APK file in order to understand how this app employs certificate pinning. Since I have proof by testing that it does implement certificate pinning I tried the different ...
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2answers
799 views

Java byte code equivalent of IDA function signatures

I remember IDA (Interactive Disassembler) has a really neat feature of function signatures where you don't have to reverse engineer code found inside standard libraries. Is there a similar feature for ...
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0answers
79 views

Decompiling Action Script code which contains special characters

I am attempting to reverse engineer a heavily obfuscated piece of Action Script code. When using JPEXS FFDec I noticed that it converted the following byte code: trait Qname(PrivateNamespace(null),"...
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1answer
1k views

Java - Decipher encrypted classes in a jar file

I have a couple of classes that are encrypted. The class loader must decrypt these before executing in the JVM. The question is, how and where? What can I do to understand who is responsible to ...
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1answer
138 views

Does anybody know which tools allow to get (pseudo) code from a Moscow ML executable?

I've decompiled Win32 executable that is the result of compilation of a program written in Moscow ML language. The resulting listing contains standard C main function that contains the call to ...
4
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2answers
404 views

Difficulty of reverse engineering based on target

I'm not asking about the difficulty of reverse engineering in general, but rather the difficulty of reverse engineering a particular hypothetical target. We'll assume that having the source code ...
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5answers
1k views

Mysterious bytecode (executable?) file from a chinese decibel meter whose manufacturer has been hacked &/or gone bankrupt

I bought a decibel meter off amazon recently (http://www.amazon.com/Sound-Measure-Tester-Pressure-Decibel/dp/B00CPKSE38/ref=sr_1_1?ie=UTF8&qid=1436376590&sr=8-1&keywords=wensn) which ...
2
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1answer
484 views

Correct reassembly of Java bytecode

I've been reverse engineering the Yikyak application, and I came across this function One particular function is used in order to verify the integrity of the API call. The decompiler failed to figure ...
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1answer
758 views

Convert C/C++ function to raw bytes [closed]

I'm planning to inject a thread into another process and unfortunately I need to write the thread function in raw bytes and can't just compile it in my program and then copy it over. The thread needs ...
4
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1answer
794 views

Protect a key from being recovered by decompilation

I work in a game editor that develop an online game. In our endless struggle against bots (that have negative impacts on server performances, game economy, game experience, ...), one of ours weapons ...
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1answer
414 views

What does a thread function look like in assembly? (LPTHREAD_START_ROUTINE, CreateRemoteThread) [closed]

Using CreateRemoteThread we can call a specific kind of function of another process. It has to be application-defined and of type LPTHREAD_START_ROUTINE. If no such function does exist in the target ...
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2answers
706 views

Matching ActionScript byte code to the Disassembly of a Shockwave Flash

There are lots of programs I seen that can locate a swf running in memory, capture it and return source code. Usually the AS byte code is generated as well. What I looking to do is the opposite, I'm ...
2
votes
1answer
563 views

Is there any documentation or examples of PHP bytecode?

I'm trying to reverse engineer a PHP obfuscator. I know that it pre-compiles the PHP to bytecode, so the recovery of original PHP source is out of scope, but I would still like to get the bytecode out....
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2answers
5k views

GUI for transforming Java Bytecode based on decompiled source?

Okay. So I've just come up with the most amazing program for java developers and reverse-engineerers and I was wondering if something like the following program already exists: What I'm thinking of ...
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2answers
2k views

How to decompile python 2.4 bytecode?

I need a good decompiler that can decompile python 2.4 byte code. I have looked over the internet and can only find python 2.5+ There are about a few hundred .pycs, so if it can decompile a directory ...
5
votes
1answer
3k views

Decompiling/disassembling lua bytecode

I've been experimenting with decompiling Lua bytecode and found useful tools like unluac, and LuaAssemblyTools. Unluac seems to do the trick with lua scripts compiled with luac giving me almost the ...
3
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1answer
615 views

Modified Java byte-code, no difference runtime

I modified the byte-code of a third party Java desktop application's .class file (and repacked the .jar), only to see that during runtime, my change made no difference, unless my change caused a crash ...
5
votes
1answer
1k views

How to create a virus signature from decompiled source

I have a problem where I have to create a virus signature for the Stoned Virus (Although this could apply to any virus/file). Let's assume I have a copy of the compiled and decompiled program. I then ...
2
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1answer
411 views

VerifyError after editingg class file with dirtJOE

I'm using dirtyJOE to edit a method of a class file. The original class file had some encryption method calls and such. I've changed the byte-code of the method ldc (byte-code: 12 1E) to load true ...
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2answers
825 views

Why does the Java compiler add an extra try-catch block?

Suppose we compile this method using Java 6+ compiler: void test(int x) { try { x += 777; } finally { x -= 333; } } The disassembled code would look like this: test(I)V ...
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1answer
618 views

Dalvik Byte code instrumentation framwork for dynamic data dependency analysis

I am looking forward to having your input regarding the availability of any tool that can do instrumentation in byte code level run-time, so that data dependency analysis can be carried out? Such tool ...
10
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2answers
753 views

Android bytecode verifier

One of the things that makes Java bytecode (.class) so easy to reverse engineer is that the JVM's verifier ensures that bytecode can always be disassembled via linear sweep. Instructions have to be ...
10
votes
1answer
6k views

Where can I find tools for reverse engineering Lua

Since Lua is an interpreted/compiled language that its own compilers and isn't usually translated/compiled with a C compiler. What tools should be used to reverse engineer an application written in ...
9
votes
1answer
1k views

Common Lisp bytecode or machine code decompiler

Does anyone know of a decompiler for Common Lisp? I know most lisp environments include a disassembler. But I don't know of any decompilers. I would think it should be possible to make a decompiler ...
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6answers
11k views

Decompiling Android application

The Android java code is compiled into Dalvik byte code, which is quite readable. I wonder, is it possible in theory and in practice to write a decompilation software for Dalvik byte code?