Debian dla-4360 : pure-ftpd - security update

#%NASL_MIN_LEVEL 80900
#
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory dla-4360. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(272225);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/11/03");

  script_cve_id("CVE-2021-40524");

  script_name(english:"Debian dla-4360 : pure-ftpd - security update");

  script_set_attribute(attribute:"synopsis", value:
"The remote Debian host is missing a security-related update.");
  script_set_attribute(attribute:"description", value:
"The remote Debian 11 host has packages installed that are affected by a vulnerability as referenced in the dla-4360
advisory.

    -------------------------------------------------------------------------
    Debian LTS Advisory DLA-4360-1                [email protected]
    https://www.debian.org/lts/security/               Santiago Ruano Rincn
    November 03, 2025                             https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : pure-ftpd
    Version        : 1.0.49-4.1+deb11u1
    CVE ID         : CVE-2021-40524
    Debian Bug     : 993810

    It was discovered that pure-ftpd, a secure and efficient FTP server,
    incorrectly verified the maximum file size in the quota mechanism, allowing
    adversaries to upload files of unbounded size. This may lead to denial of
    service or a server hang.

    For Debian 11 bullseye, this problem has been fixed in version
    1.0.49-4.1+deb11u1.

    We recommend that you upgrade your pure-ftpd packages.

    For the detailed security status of pure-ftpd please refer to
    its security tracker page at:
    https://security-tracker.debian.org/tracker/pure-ftpd

    Further information about Debian LTS security advisories, how to apply
    these updates to your system and frequently asked questions can be
    found at: https://wiki.debian.org/LTS
    Attachment:
    signature.asc
    Description: PGP signature

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/source-package/pure-ftpd");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2021-40524");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/bullseye/pure-ftpd");
  script_set_attribute(attribute:"solution", value:
"Upgrade the pure-ftpd packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-40524");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/09/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/11/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/11/03");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pure-ftpd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pure-ftpd-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pure-ftpd-ldap");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pure-ftpd-mysql");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pure-ftpd-postgresql");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:11.0");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Debian Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);

var debian_release = get_kb_item('Host/Debian/release');
if ( isnull(debian_release) ) audit(AUDIT_OS_NOT, 'Debian');
debian_release = chomp(debian_release);
if (! preg(pattern:"^(11)\.[0-9]+", string:debian_release)) audit(AUDIT_OS_NOT, 'Debian 11.0', 'Debian ' + debian_release);
var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Debian', cpu);

var pkgs = [
    {'release': '11.0', 'prefix': 'pure-ftpd', 'reference': '1.0.49-4.1+deb11u1'},
    {'release': '11.0', 'prefix': 'pure-ftpd-common', 'reference': '1.0.49-4.1+deb11u1'},
    {'release': '11.0', 'prefix': 'pure-ftpd-ldap', 'reference': '1.0.49-4.1+deb11u1'},
    {'release': '11.0', 'prefix': 'pure-ftpd-mysql', 'reference': '1.0.49-4.1+deb11u1'},
    {'release': '11.0', 'prefix': 'pure-ftpd-postgresql', 'reference': '1.0.49-4.1+deb11u1'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var _release = NULL;
  var prefix = NULL;
  var reference = NULL;
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['prefix'])) prefix = package_array['prefix'];
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (_release && prefix && reference) {
    if (deb_check(release:_release, prefix:prefix, reference:reference)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : deb_report_get()
  );
  exit(0);
}
else
{
  var tested = deb_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'pure-ftpd / pure-ftpd-common / pure-ftpd-ldap / pure-ftpd-mysql / etc');
}