id: CVE-2021-40859

info:
  name: Auerswald COMpact 5500R 7.8A and 8.0B Devices Backdoor
  author: pussycat0x
  severity: critical
  description: Auerswald COMpact 5500R 7.8A and 8.0B devices contain an unauthenticated endpoint ("https://192.168.1[.]2/about_state"), enabling the bad actor to gain backdoor access to a web interface that allows for resetting the administrator password.
  remediation: |
    Apply the latest firmware update provided by Auerswald to fix the backdoor vulnerability.
  reference:
    - https://thehackernews.com/2021/12/secret-backdoors-found-in-german-made.html
    - https://nvd.nist.gov/vuln/detail/CVE-2021-40859
    - https://www.redteam-pentesting.de/en/advisories/-advisories-publicised-vulnerability-analyses
    - https://www.redteam-pentesting.de/en/advisories/rt-sa-2021-007/-auerswald-compact-multiple-backdoors
  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-2021-40859
    epss-score: 0.02655
    epss-percentile: 0.89264
    cpe: cpe:2.3:o:auerswald:compact_5500r_firmware:7.8a:build002:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: auerswald
    product: compact_5500r_firmware
    fofa-query: '"auerswald"'
  tags: cve,cve2021,iot,unauth,voip,auerswald

http:
  - method: GET
    path:
      - "{{BaseURL}}/about_state"

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '"pbx"'
          - '"dongleStatus":0'
          - '"macaddr"'
        condition: and

      - type: word
        part: header
        words:
          - "application/json"

      - type: status
        status:
          - 200
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