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效果展示

在这里插入图片描述

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

1. main.js

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

2. dog.js

let result = "dog is running!";
toastLog(result);

frida的Hook代码

1. 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(c);
    let result = this.decrypt(a, b, c);
    let s = String.$new(result);
    console.log("s ====================");
    console.log(s);
    return result;
  };
});

2. 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("")
  );
}

3. 方法堆栈

com.stardust.autojs.engine.encryption.ScriptEncryption.decrypt(Native Method)
com.stardust.autojs.engine.encryption.ScriptEncryption$Companion.decrypt()
com.stardust.autojs.engine.encryption.ScriptEncryption$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)

4. 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$default(ScriptEncryption scriptEncryption, byte[] bArr, int i2, int i3, int i4, Object obj)
com.stardust.autojs.engine.encryption.ScriptEncryption.decrypt(byte[] bArr, int i2, int i3)
com.stardust.autojs.project.ProjectConfig.ScriptEncryption$Companion.decrypt(byte[] bArr, int i2, int i3)