How to realize the Analysis of Vmware vcenter unauthorized arbitrary File vulnerability CVE-2021-21972

How to realize the analysis of Vmware vcenter unauthorized arbitrary file vulnerability CVE-2021-21972, aiming at this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

First, vulnerability description

CVE-2021-21972 is an unauthorized command execution vulnerability of VMware vcenter. The vulnerability can upload a webshell to any location on the vcenter server and then execute webshell.

VSphere Client (HTML5) contains a remote code execution vulnerability in the vCenter Server plug-in. Unauthorized attackers can send specially crafted requests to vCenter Server through a server with port 443 open, thereby writing webshell on the server, resulting in remote arbitrary code execution. In the CVE-2021-21972 VMware vCenter Server remote code vulnerability, an attacker can construct a malicious request directly through port 443, execute arbitrary code, and control vCenter.

2 affected version and vulnerability rating

VMware vCenter Server 7.0Series

< 7.0.U1c VMware vCenter Server 6.7系列 < 6.7.U3l VMware vCenter Server 6.5系列 < 6.5 U3n 漏洞评级：严重 CVSS#3.1 :9.8 FIRST CVSSv3 Calculator: CVE-2021-21972: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 三，安全版本 VMware vCenter Server 7.0.U1c VMware vCenter Server 6.7.U3l VMware vCenter Server 6.5 U3n 漏洞分析: vCenter Server 的 vROPS 插件的 API 未经过鉴权，存在一些敏感接口。其中 uploadova接口存在一个上传 OVA 文件的功能：代码逻辑是将 TAR 文件解压后上传到 /tmp/unicorn_ova_dir目录。 直接将 TAR 的文件名与 /tmp/unicorn_ova_dir拼接并写入文件。如果文件名内存在 ../即可实现目录遍历。对于 Linux 版本，可以创建一个包含 ../../home/vsphere-ui/.ssh/authorized_keys的 TAR 文件并上传后利用 SSH 登陆. 四，poc: poc 访问https:///ui/vropspluginui/rest/services/updateova 如果404，则代表不存在漏洞，如果200，405 则代表存在漏洞

Repair methods and suggestions:

Follow the official prompts to close the plug-in https://kb.vmware.com/s/article/82374

Safety recommendation

1. Upgrade VMware vCenter Server and VMware ESXi to the latest version.

2. CVE-2021-21972 VMware vCenter Server remote code vulnerabilities and CVE-2021-21973 VMware vCenter Server SSRF vulnerabilities can be mitigated according to https://kb.vmware.com/s/article/82374-related measures.

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