Questions tagged [java]

Java is an object-oriented language and runtime environment (JRE). Java programs are platform independent, because they are compiled to bytecode and their execution is handled by a Virtual Machine called the Java VM or JVM.

33 questions with no upvoted or accepted answers
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How can I tell whether or not a given library method is being referenced by a consumer program statically in OOP languages?

Preface: This question is about source code reverse engineering and static analysis. Meaning, there is no built code available but I have access to the source code of the program. Imagine I'm looking ...
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1answer
414 views

Reverse engineering android native packer

im trying to Reverse engineering an android app and the app have 4 folders in the /data/data/{package} folder ├───app_dexprotector │ 823517D25836B88F1C499C02370A047E.dat │ ...
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Google Maps, Android serialisation format

I've come across an SQLite database (gmm_storage.db) used by Google Maps on Android, and I'm unsure as to how the data it contains is serialised. For example: I'm saying serialised, as from the ...
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142 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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419 views

Jar reversing: Can't open as zip file nor open it with common decompilers

I'm pentesting a JNLP application composed by several .jar files. I'm able to decompile with jd-gui every 3rd party library included in it, but the main .jar coded by my client. So after running JD-...
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Javascript equivalent of JEB

In case you already know, there is a full-feature decompiler for Java/Android called JEB (https://www.pnfsoftware.com/) Some of the most important features include the ability to rename identifiers ...
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85 views

JEB Decompiler - Signature recognition engine

I've been playing around with the JEB decompiler and Android reverse engineering suite. One interesting feature they have is deobfuscation by library code matching in which 3rd party libraries out ...
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262 views

Some obstacles in reversing a JNI Native library

I deleted my last question (it was not still answered and none's effort was wasted) as I got back and thought to re-read JNI documentation, to find I misinterpreted some bits. Things are now clearer ...
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1k views

Obfuscated Config Files: EHI Files for HTTP Injector

So I have an ehi file, which is a configuration file for an Android App called HTTP Injector. Of course when I try to see it as a simple text, I just get random characters. What tool could I use to ...
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168 views

Calling functions of a shared object (.so) extracted from an APK

Decompiling a regular Android application I noticed that its code uses some native functions. So, unpacking the (.apk) file I found the usual "lib" folder and under that a series of folders for ...
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826 views

decompiled android application with only one class [DexProtector]

I'm trying to reverse engineering an android app and it's mostly for an experiment but I have a problem that I can't find a solution or even what is the problem. I decompiled an app with JADX-gui and ...
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155 views

Common practices for 'hiding' a class within an Android application?

I've recently gotten into Android reverse engineering, and I've been messing around with some apps lately for education/research purposes to see how some things are done with private (mobile) APIs. ...
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Intercept traffic from exe to my Java server

In Windows 10, I can easily intercept traffic of an application using Proxifier and route it to Charles proxy, so that I can inspect and edit the data. exe -> Proxifier (Socks proxy to localhost:...
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Is there any way to get value from bytecode under JDWP without access to source?

When I debug android app through jdwp using jdb, it seems I can't get anything from the bytecode level. I know normally it's fine as long as we have the source line info and use a decompiler, but the ...
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394 views

Java Bytecode edit

Hi, I would like to edit one compiled java class file & like to insert & edit a couple of lines. I'm trying to make a patch for a software & when I compare this two file the only change I ...
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196 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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82 views

Accessing debug log on Java application

I'm currently reverse engineering a JSP applet running through JBoss. Decompiling the code it looks like there are a bunch of Logger.debug() calls in the code that aren't guarded. A quick read through ...
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1answer
205 views

Certain classes do not show up in JDB while they are present in source code

I'm debugging a closed-source Android app with jdb. In the output produced by the apktool, I see class com.myapp.j.d.d, as well as a/b/c/e, but at run-time, I see only com.myapp.j.d.e. Why is that ...
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Java Software cleanroom implementation

I'm trying to make a cleanrooom implementation of a java written lib. What resources can I use for it. Only the official software docs? Or can I use what I get after i throw the lib into a java ide (...
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How do I decode or decompile this class It seems codes are encrypted?

I've used JD-Gui, Luyten and other couple of Java Decompilers but it's not working what is the problem in here? Thanks! It's A Mod (Minecraft) and I'm porting into different versions. Code: public ...
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1answer
53 views

Java Help Understanding RSA Encrypt/Decrypt file and SD card

I was directed tyhis way from the main superuser site: I have zero experience with Java or Android apps (have coding experience in C) and tried reverse engineering a [now defunct/unsupported] app ...
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“strings” command from *nix, but as a Java API?

Looking for the "strings" command from *nix, but as a Java API. Does such a library or JAR exist? I've automated calling the strings *nix command, but would like to explore reverse ...
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How can I find the native functions used by the Java Runtime Environment on Linux?

I am not usually a Java programmer, but I need to locate for example, which native functions (or APIs) are used in something like java.io.File.createNewFile() on Linux? Initially, I am thinking of 2 ...
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1answer
57 views

Making a Android Toast via JNI, i.e. calling Java methods via JNI

Concerning the outputting of an Toast, I found that there are some ways to make a Toast, that invoke calling a FindClass on JNIEnv object with the android/widget/Toast parameter, but I found no ...
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Tracing all (or most of) function calls in a specific Android app

I'm having a problem, where I'm trying to trace some function calls in an Android app, that uses JNI for about all of its work. More specifically, a function call, in JNI, that makes (IIRC Android ...
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App crashes upon launch after apktool d, apktool b without changing anything

I would like to modify some codes via apktool. However it crashes once I signed it and installed it. I have tried resigned it without using apktool. It works. So I am pretty sure that the app does ...
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Get Unaffected and KilledByCall Registers from CompilerSpec using Ghidra's Java API

Is there a way to get the volatile and non-volatile registers from Ghidra's CompilerSpec? For instance, when I look into the ARM.cspec I get the following information: <unaffected> <register ...
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1answer
142 views

frida - The specified child already has a parent. You must call removeView() on the child's parent first when hooking, how do you solve it?

I wanted to hook the method A1f in the below code but frida returns the following exceptions: Found instance: MyHomeFragment{9bbd8d5} (0965bca9-4838-4ca1-a835-d99639ae15f1)} java.lang....
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60 views

Hashing algorithm of length 50

I have been trying to reverse-engineer an Android application using Jadx for static analysis and Frida for dynamic analysis. The end goal is to be able to re-create the request signature, sent as a "x-...
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2answers
95 views

Load Library Android

I Work as cybersecurity consultant and now i'am in mission to reverse engineering of mobile app. I always reverse it using Jadx and dex2jar ... the problem that after reverse them i found some native ...
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2answers
981 views

What functions (in which modules) can be hooked by Frida to access unencrypted data of SSL connections in Java programs running under Windows?

There are gazillions of internet resources discussing how to use Frida to hook and otherwise mess around with SSL connections of Java programs running under Android, but seemingly (as far as my google-...
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decomplied apk with bad parameters

I'm trying to reverse engineering an android app API so this is what I tried: First the app was using Okhttp certificate pinning and I couldn't track the URLs with Charles then I tried this method ...
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1answer
327 views

how to deobfuscate to java zkm?

I will have a question for you, dear forum residents. I have a .jar file encrypted with ZKM which I think will work for me. I don't know how to decrypt this, can you help me?