Debian dla-4195 : krb5-admin-server - 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-4195. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(237586);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/05/30");

  script_cve_id("CVE-2025-3576");

  script_name(english:"Debian dla-4195 : krb5-admin-server - 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-4195
advisory.

    - -------------------------------------------------------------------------
    Debian LTS Advisory DLA-4195-1                [email protected]
    https://www.debian.org/lts/security/                   Bastien Roucaris
    May 30, 2025                                  https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : krb5
    Version        : 1.18.3-6+deb11u7
    CVE ID         : CVE-2025-3576
    Debian Bug     : 1103525

    A Vulnerability in the MIT Kerberos implementation
    allows GSSAPI-protected messages using RC4-HMAC-MD5
    to be spoofed due to weaknesses in the MD5 checksum design.
    If RC4 is preferred over stronger encryption types,
    an attacker could exploit MD5 collisions to forge message
    integrity codes. This may lead to unauthorized
    message tampering.

    In order to fix CVE-2025-3576, vulnerable cryptographic
    algorithms for tickets need to be disabled explicitly
    with the new allow_rc4 or allow_des3 variables.

    According to the vulnerability report Kerberos?? RC4-HMAC broken
    in practice: spoofing PACs with MD5 collisions, disabling
    this cryptographic algorithm may break some older
    authentication systems, and administrators should test carefully.

    Because of the risk of breaking certain configurations, the
    new allow_rc4 or allow_des3 are being treated as having a
    default value of 'true' for updates to older Debian releases.
    This leaves the 3DES and RC4 algorithms enabled, but administrators
    are strongly encouraged to disable them after verifying
    compatibility in their environments.

    For Debian 11 bullseye, this problem has been fixed in version
    1.18.3-6+deb11u7.

    We recommend that you upgrade your krb5 packages.

    For the detailed security status of krb5 please refer to
    its security tracker page at:
    https://security-tracker.debian.org/tracker/krb5

    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

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/krb5");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2025-3576");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/bullseye/krb5");
  script_set_attribute(attribute:"solution", value:
"Upgrade the krb5-admin-server packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:N/I:C/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2025-3576");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2025/04/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/05/30");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/05/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-admin-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-gss-samples");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-k5tls");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-kdc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-kdc-ldap");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-kpropd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-locales");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-multidev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-otp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-pkinit");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:krb5-user");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libgssapi-krb5-2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libgssrpc4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libk5crypto3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkadm5clnt-mit12");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkadm5srv-mit12");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkdb5-10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrad-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrad0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrb5-3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrb5-dbg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrb5-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkrb5support0");
  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': 'krb5-admin-server', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-doc', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-gss-samples', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-k5tls', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-kdc', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-kdc-ldap', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-kpropd', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-locales', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-multidev', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-otp', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-pkinit', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'krb5-user', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libgssapi-krb5-2', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libgssrpc4', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libk5crypto3', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkadm5clnt-mit12', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkadm5srv-mit12', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkdb5-10', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrad-dev', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrad0', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrb5-3', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrb5-dbg', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrb5-dev', 'reference': '1.18.3-6+deb11u7'},
    {'release': '11.0', 'prefix': 'libkrb5support0', 'reference': '1.18.3-6+deb11u7'}
];

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, 'krb5-admin-server / krb5-doc / krb5-gss-samples / krb5-k5tls / etc');
}