Hook逆向离线加密的autojs打包的脚本

效果展示

环境

雷电模拟器Android版本: 7.1.2

Android Studio版本: 4.1.2

jadx-gui版本: 1.2.0

流程

用autojs打包app, 安装到雷电模拟器
用jadx-gui查看app, 主要是查看包名类名
执行frida的hook命令, hook可疑的类, 主要是包含decrypt的类名
打印可疑decrypt方法的参数和返回值, 脚本内容就直接出来了

autojs的测试代码

main.js

engines.execScriptFile("./dog.js");

dog.js

let result = “dog is running!”;
toastLog(result);

frida的Hook代码

hook.js

Java.perform(function () {
var String = Java.use(“java.lang.String”);
var clazz5 = Java.use(“com.stardust.autojs.engine.encryption.ScriptEncryption”);
clazz5.decrypt.implementation = function (a, b, c) {
console.log(“com.stardust.autojs.engine.encryption.ScriptEncryption”);
console.log(“a =”);
console.log(a);
console.log(“b =”);
console.log(b);
console.log(“c =”);
console.log©;
let result = this.decrypt(a, b, c);
let s = String.$new(result);
console.log(“s ====================”);
console.log(s);
return result;
};
});

打印方法堆栈

function trace() {
var throwable = Java.use(“java.lang.Throwable”);
send(
“Backtrace:\n\t” +
throwable
.$new()
.getStackTrace()
.map((traceElement) => traceElement.toString() + “\n\t”)
.join("")
);
}

方法堆栈

com.stardust.autojs.engine.encryption.ScriptEncryption.decrypt(Native Method)
com.stardust.autojs.engine.encryption.ScriptEncryption $C o m p a n i o n . d e c r y p t () c o m . s t a r d u s t . a u t o j s . e n g i n e . e n c r y p t i o n . S c r i p t E n c r y p t i o n$ Companion.decrypt$default()
d.g.c.o.g.a.b(:4)
d.g.c.o.g.a.doExecution(:2)
com.stardust.autojs.engine.JavaScriptEngine.execute()
com.stardust.autojs.engine.LoopBasedJavaScriptEngine.access$001()
d.g.c.n.c.run(:2)
android.os.Handler.handleCallback(Handler.java:751)
android.os.Handler.dispatchMessage(Handler.java:95)
android.os.Looper.loop(Looper.java:154)
com.stardust.autojs.engine.LoopBasedJavaScriptEngine.execute()
com.stardust.autojs.engine.LoopBasedJavaScriptEngine.execute()
com.stardust.autojs.execution.LoopedBasedJavaScriptExecution.doExecution()
com.stardust.autojs.execution.RunnableScriptExecution.execute()
com.stardust.autojs.execution.RunnableScriptExecution.execute()
com.stardust.autojs.execution.RunnableScriptExecution.run()
java.lang.Thread.run(Thread.java:761)

可疑类, 用jadx搜索关键词 decrypt

com.stardust.autojs.engine.encryption.ScriptEncryption.decrypt(byte[], int, int)
com.stardust.autojs.engine.encryption.ScriptEncryption.decrypt $d e f a u l t (S c r i p t E n c r y p t i o n s c r i p t E n c r y p t i o n, b y t e [] b A r r, i n t i 2, i n t i 3, i n t i 4, O b j e c t o b j) c o m . s t a r d u s t . a u t o j s . e n g i n e . e n c r y p t i o n . S c r i p t E n c r y p t i o n . d e c r y p t (b y t e [] b A r r, i n t i 2, i n t i 3) c o m . s t a r d u s t . a u t o j s . p r o j e c t . P r o j e c t C o n f i g . S c r i p t E n c r y p t i o n$ Companion.decrypt(byte[] bArr, int i2, int i3)

总结

脚本打包使用离线加密的时候, javascript脚本本身应该先混淆一遍, 然后再用离线打包,

或者, 直接使用自带的离线Dex加密或者离线Snapshot加密

List item

Hook逆向离线加密的autojs打包的脚本

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