Pure-FTPd < 1.0.50 - DoS via Resource Exhaustion

id: CVE-2019-20176

info:
  name: Pure-FTPd < 1.0.50 - DoS via Resource Exhaustion
  author: pussycat0x
  severity: high
  description: |
    Pure-FTPd versions prior to 1.0.50 are vulnerable to resource exhaustion leading to denial of service. The vulnerability occurs in the listdir() function when processing crafted LIST commands, causing stack exhaustion that can crash the FTP server.
  impact: |
    Unauthenticated attackers can send crafted LIST commands to exhaust stack resources in the listdir() function, causing denial of service by crashing the Pure-FTPd server.
  remediation: |
    Update Pure-FTPd to version 1.0.50 or later that properly handles LIST command processing and prevents stack exhaustion vulnerabilities.
  reference:
    - https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AHZG5FPCRMCB6Z3L7FPICC6BZ5ZATFTO/
    - https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PICL3U2J4EPGBLOE555Y5RAZTQL3WBBV/
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    cvss-score: 7.5
    cve-id: CVE-2019-20176
    cwe-id: CWE-400
    epss-score: 0.04365
    epss-percentile: 0.91333
    cpe: cpe:2.3:a:pureftpd:pure-ftpd:1.0.49:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: pureftpd
    product: pure-ftpd
    shodan-query:
      - product:"pure-ftpd" version:"1.0.45"
      - cpe:"cpe:2.3:a:pureftpd:pure-ftpd"
  tags: cve,cve2019,network,ftp,pure-ftpd,tcp,passive,vuln

tcp:
  - inputs:
      - data: 00000000
        type: hex

    host:
      - "{{Hostname}}"

    port: 21
    read-size: 1024

    matchers:
      - type: dsl
        dsl:
          - "contains(raw, 'Pure-FTPd')"
          - "compare_versions(version, '< 1.0.50')"
        condition: and

    extractors:
      - type: regex
        group: 1
        name: version
        regex:
          - "Pure-FTPd ([0-9.]+)"