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.

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How to set global variable type?

I have created a script in Java and I have a structure type as a string name which I want to set at given global variable which I have the Address of. However I can't seem to find a way to do this - ...
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How to utilize `FillOutStructureCmd`?

Basically I'm extending the CreateStructure.java plugin so it iterates all functions and tries to automatically create structures on all variables. It looks something like this: public class ...
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Where can I find the encryption algorithm for this POST request in an Android APP?

I have an Android app for which I need to mock an API call outside of that environment. I successfully killed the certificate pinning on this app with Frida in order to access the URL and more, but ...
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Decompile obfuscated jar file

Tried java-deobfuscator and other things, detect said it was allatori protected so tried the relevant transformers but to no avail. Please can someone help, I'm happy to tip for your help :) https://...
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Trace java calls from a native library using frida

Im trying to trace method calls from a native library using frida I've tried jnitrace but it won't print anything Do you have any suggestion?
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1 vote
1 answer
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Where can I find the encryption algorithm in source code?

When I submit a Customer Reference ID in an Android Application it POSTs an encrypted string to an API endpoint. For example, if I enter the following CR ID : "SR-54585482" it POSTs the ...
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SQLite access from Ghidra script

I would like to access an SQLite database from within a Java Ghidra script. However, if I include the line import java.sql.*; in the script, Ghidra gives the error > Unable to locate script class:. ...
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What is this CRC32 algorithm (written in C), and how can it be written in Java or Python?

I've been trying to convert this CRC32 algorithm to Java or Python, but I haven't been successful, I believe it's because I'm not familiar enough with c. Note that I believe DAT_804818d0 is the seed, ...
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4 votes
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Patching Jar File (2022)

Currently reversing a .jar program recreationally, and I understand the workflow proposed here: https://www.netspi.com/blog/technical/thick-application-penetration-testing/patching-java-executables-...
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<"..." is not a valid class name"> when trying to debug an android app using jdb

I am trying to reverse engineer an android app for education purpose, but I ran into an annoying problem: the android app is obfuscated and some classnames start with digits. So when I tried putting a ...
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Injecting class into the JNIEnv in android jni

void *handle = dlopen("/data/local/tmp/libnative-lib.so", RTLD_LAZY); if (!handle) { printf("\nFailed to load library\n"); } void *offset = dlsym(handle, "...
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1 vote
1 answer
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Determine if exe is written using Java

I'm examining my Windows programs to determine which ones are written in Java, and if so, whether they import a log4j library affected by the log4shell vulnerability. Programs that are packaged as JAR ...
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Ghidra: Iterating over function's codeUnits returns only 1st instruction

public void run() throws Exception { var cp = currentProgram; var nsSymbols = ghidra.app.util.NamespaceUtils.getSymbols("myNameSpace", cp); var glNS = nsSymbols.get(0)...
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How to deobfuscate Java application

Hi i am unable to deobfuscate the Advanced String Obfuscation Jar on tryHackMe I tried dumping the classes using a dumper javaagent deobfuscate the jar with java-deobfuscator threadtear functions ...
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1 vote
1 answer
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Java Malware Dollar Sign

I am analyzing a mobile malware sample and got a trouble. When i put sample in JADX, i see some dollar sign. I mean like this; What does these dollar signs means?
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Need help logging string in smali

I'm trying to log p1 string to logcat. This is my function. new-instance v4, Ljava/lang/StringBuilder; invoke-direct {v4}, Ljava/lang/StringBuilder;-><init>()V invoke-virtual {v4, v3}, ...
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Capturing created and deleted files from a Java file

I am new to the malware analysis field but I do have an issue, a file I am working on creates 2 vbs files, reads from them and deletes them, this all happens in around 2 seconds. Also this is a Java ...
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Checksum verification of an apk does not the same as my java program

I'm from the sysadmin side of the IT and have not much experience in programing. I have an app that lets me screen share Android apps on my car's display. Sadly there is a whitelist baked into the app,...
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Is this native code possible for further static analysis?

I was trying to reverse engineer a native lib code in an android app. the .so contains many functions. But the function sUQWWyTBEs() was referred in the Java code. I was curious how this function ...
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what do these assembly code doing?

I tried to reverse engineer an apk app, and it was loading a native code. I have observed that the app was using the native code like this public static String v = sUQWWyTBEs().toString().substring(32,...
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  • 179
1 vote
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What tools can be appropriate to reverse engineer a (open-source) java program?

I am very new reverse engineering, and have the below mentioned tasks to achieve on a open source program called Apache Ant. What (preferably free) tools can be appropriate to achieve these. I have ...
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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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2 votes
1 answer
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How to decompile heavily obfuscated classes mixed with Arabic/Chinese/Korean characters?

I recently downloaded a jar file and was curious to see if it was malicious, so I ran it through FernFlower and it wasn't able to deobfuscate it. When I unzipped the jar, I looked inside it and saw ...
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1 answer
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Java Help Understanding RSA Encrypt/Decrypt file and SD card

I was directed this way from the main superuser site: I have zero experience with Java or Android apps (I have coding experience in C) and tried reverse engineering a [now defunct/unsupported] app ...
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3 votes
2 answers
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Frida reading files is slow

I need to read a file around 2 MB into a byte array. var fis = Java.use("java.io.FileInputStream"); var file = fis.$new("/data/local/file.txt"); var fileBytes = new Uint8Array(file....
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2 votes
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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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1 vote
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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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1 vote
1 answer
313 views

How can I see when a library is being called in Android?

Apologies for a beginner-esque question, but I am reverse engineering an Android application, that is most probably using the libusbhost.so library to interface with USB devices via Java Native ...
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1 answer
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Recaf: Recompile disabled, can't edit

I've download recaf jar file and install JDK 8. When I execute it/start it, it all works fine with java -jar recaf-2.12.0-J8-jar-with-dependencies.jar. I open a class file also no problem. The issue ...
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3 votes
0 answers
33 views

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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-2 votes
1 answer
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How to deobfuscate Java application protected by Java Antidecompiler [closed]

Here is some infomation I found from MANIFEST.MF Archiver-Version: Plexus Archiver Built-By: boonb Created-By: Apache Maven Build-Jdk: 1.8.0_231 Main-Class: JavaLauncher Modified-By: 9.4 (BIS Guard &...
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1 vote
1 answer
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Accessing Call String of CALLOTHER Pcode Instruction via Java API?

Is there a way to access the call string of a CALLOTHER Pcode instruction when iterating over the Pcode in Java? The listing below shows an example of what I mean: 048 ...
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2 votes
1 answer
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How do we decompile java so easy?

I have seen a lot of videos where everyone is decompiling the jar files so easily. but I learnt that we cannot decompile any compiled file so easily. I have a little bit of experience in Gidhra. I ...
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1 vote
1 answer
297 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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-3 votes
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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?
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1 vote
1 answer
432 views

Calling a method of a Java object passed as argument to hooked function in Frida

I am trying to obtain the SecretKey passed to the decryptAesCipherText function. I hooked the function in Frida to try to print out the arguments when the method is called but since SecretKey is an ...
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2 votes
1 answer
1k views

How to Launch and debug Ghidra from Eclipse with two Modules I'm developing at the same time?

Ghidra comes with its own Eclipse extensions that allows you to develop new Scripts and Modules for Ghidra. I'm working on several new Modules for Ghidra that will work together. But I've basically ...
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1 vote
2 answers
388 views

Working with strong obfuscated Java

I've got a jar file, that is strong obfuscated. When I tried to put it into decompilers such as bytecode-viewer and luyten I seen many lines of traps and Chinese letters. I tried to deobfuscate it ...
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1 vote
1 answer
557 views

Dynamic analysis (Frida) reveals instance of a class that doesn't exist in the source code (dex2jar)

I have been diving into an apk's source code, doing both static analysis with Jadx (same as dex2jar) and dynamic analysis with Frida. I am trying to replicate the method that signs HTTP requests "...
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0 votes
0 answers
104 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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1 vote
1 answer
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Reverse Engineering Java - Deobfuscating symbols

I'm new to Java and working on cleaning up a fairly large Java .jar sample where the obfuscator has renamed symbols into invalid names. For example: import org.lib.00.0.2; public final class 90 ...
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1 vote
1 answer
524 views

How can I get classes from "protected" JAR file?

I'm trying to get classes from JAR file / actually running JVM machine but: When I'm trying to open JAR file using for example 7Zip I dont see any classes. After unzip Manifest file is empty too. When ...
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3 votes
1 answer
304 views

How can I retrieve the encryption key in this code?

can anyone explain the following code? is it possible to retrieve the encryption key? I think the code was heavily obfuscated in addition to obfuscation, I can recognize it is using algorithms like ...
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1 vote
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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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1 vote
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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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3 votes
2 answers
3k views

Dealing with heavily obfuscated Java, possibly on bytecode level

I've got a jarfile from a friend, he told me to put it thru an decompiler. So I did, but: JD-GUI basically spit out just the imports and didn't show any class data CFR dumped out stack trace on ...
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0 votes
2 answers
174 views

Load Library Android

I work as cybersecurity consultant, and now I am on 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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1 vote
2 answers
274 views

J2ME games obfuscator - Spyro and Tekken 5

While reversing some J2ME games like Spyro or Tekken 5 Mobile I have encountered a weird obfuscation where all fields, methods and classes have names like A, a, B, b, Aa, Bb etc. It's really hard to ...
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2 votes
0 answers
186 views

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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2 votes
2 answers
919 views

Java reverse engineering tool [closed]

I'm getting started on Java reverse engineering but I can't find a great tool. I'm currently using JD-Gui to decompile it. I've tried PNF's JEB which is really perfect but it's only for Android stuff....
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