Most reverse engineers mainly use Java decompiler, commercial dalvik decompiler Jeb and smali2java to analyze Android APPs. Java decompiler is based on Java bytecode, including JD, JD-GUI, jadx, and others. smali2java is a decompiler based on Smali code. They have their own shortcomings, such as Java decompiler depends on convert of dex2jar. For complex, obfuscated or packed apks, there are problem of translation failure. smali2java decompiles Smali code which should be translated from DEX with apktool, so it increases the difficulty and error rate, and decreases the speed of manual analysis. In addition, their interaction is poor, which increases the difficulty of manual analysis. Although the commercial Jeb has better interactivity, it is easy to death when analyzing large-sized APP with the Multidex, and it is very expensive...
Here, a new decompiler based on Dalvik bytecode, GDA, is proposed and implemented in C++ language to provide more sophisticated, fast and convenient decompilation support. GDA is completely self-independent. It supports APK, DEX, ODEX, oat files, and run without installation and Java VM support. GDA only takes up 2M of your disk space, and you can use it in any newly installed windows system and virtual machine system. In addition, GDA has more features as follows:
Interactive operation:
1.cross-references for strings, classes, methods and fields;
2.searching for strings, classes methods and fields;
3.comments for java code;
4.rename for methods,fields and classes;
5.save the analysis results in gda db file.
...
Utilities for Assisted Analysis:
1.extracting DEX from ODEX;
2.extracting DEX from OAT;
3.XML Decoder;
4.algorithm tool;
5.device memory dump;
...
New features:
1.Brand new dalvik decompiler in c++ with friendly GUI;
2.Support python script
3.packers Recognition;
4.Multi-DEX supporting;
5.making and loading signature of the method
6.Malicious Behavior Scanning by API chains;
7.taint analysis to preview the behavior of variables;
8.taint analysis to trace the path of variables;
9.de-obfuscate;
10.API view with x-ref;
11.Association of permissions with modules;
...
GDA shortcut key
| shortcut | description |
|---|---|
| F5 | Switch java to smali, pressing it again for back to java |
| F | Trace the args and return value by dataflow analysis |
| X | Cross-referencing, locating callers (of strings, classes, methods, field, Smali, Java) |
| Esc/<-/Backspace | Back to the last visit |
| -> | Forward to the next visit |
| G | Jump to somewhere by you inputting offset |
| N | Rename the variable/method/class name |
| S | Search for all the elements by the given string |
| C | Comments. Only supports the Java code |
| DoubleClick | The cursor's placed at the method/str/field/class, and double-click to access objects |
| M | the cursor's placed at the Smali line and pressing the key 'M' to edit the instruction |
| UP | Press 'up' key to access the up-method in the tree control |
| Down | Press “down” key to access the down-method in the tree control |
| D | Dump the binary data of methods, only supports the Smali window |
| Enter | The modification of edit boxes take effect |
| H | Show data in Hex |
| Ctr+H | Pop searching history window |
| Ctr+A | Select all |
| Ctr+C | Copy |
| Ctr+V | Paste, only for editable boxes |
| Ctr+X | Cut |
| Ctr+F | Find out the string of the current window |
| Ctr+S | Save the modifications into the GDA database file |
not yet, just double-click the bin and you can enjoy it.
Only for windows
brief guide: https://github.com/charles2gan/GDA-android-reversing-Tool/wiki
python script:https://github.com/charles2gan/GDA-android-reversing-Tool/wiki/GDA-Python-scripts
File loading and decompiling:
MalScan, API search, x-ref...
Url,Xml,string x-ref...
variable trace
