Alibaba Cloud Linux 3 : 0041: dhcp (ALINUX3-SA-2021:0041)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The package checks in this plugin were extracted from
# Alibaba Cloud Linux Security Advisory ALINUX3-SA-2021:0041.
##

include('compat.inc');

if (description)
{
  script_id(236530);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/05/14");

  script_cve_id("CVE-2021-25217");

  script_name(english:"Alibaba Cloud Linux 3 : 0041: dhcp (ALINUX3-SA-2021:0041)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Alibaba Cloud Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Alibaba Cloud Linux 3 host has packages installed that are affected by a vulnerability as referenced in the
ALINUX3-SA-2021:0041 advisory.

    Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

    CVE-2021-25217:
    In ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16, ISC DHCP 4.4.0 -> 4.4.2 (Other branches of ISC DHCP (i.e., releases
    in the 4.0.x series or lower and releases in the 4.3.x series) are beyond their End-of-Life (EOL) and no
    longer supported by ISC. From inspection it is clear that the defect is also present in releases from
    those series, but they have not been officially tested for the vulnerability), The outcome of encountering
    the defect while reading a lease that will trigger it varies, according to: the component being affected
    (i.e., dhclient or dhcpd) whether the package was built as a 32-bit or 64-bit binary whether the compiler
    flag -fstack-protection-strong was used when compiling In dhclient, ISC has not successfully reproduced
    the error on a 64-bit system. However, on a 32-bit system it is possible to cause dhclient to crash when
    reading an improper lease, which could cause network connectivity problems for an affected system due to
    the absence of a running DHCP client process. In dhcpd, when run in DHCPv4 or DHCPv6 mode: if the dhcpd
    server binary was built for a 32-bit architecture AND the -fstack-protection-strong flag was specified to
    the compiler, dhcpd may exit while parsing a lease file containing an objectionable lease, resulting in
    lack of service to clients. Additionally, the offending lease and the lease immediately following it in
    the lease database may be improperly deleted. if the dhcpd server binary was built for a 64-bit
    architecture OR if the -fstack-protection-strong compiler flag was NOT specified, the crash will not
    occur, but it is possible for the offending lease and the lease which immediately followed it to be
    improperly deleted.

Tenable has extracted the preceding description block directly from the Alibaba Cloud Linux 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:"http://mirrors.aliyun.com/alinux/3/cve/alinux3-sa-20210041.xml");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:A/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:A/AC:L/PR:N/UI:N/S:C/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-2021-25217");

  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:"2021/05/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/07/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/05/14");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-client");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-client-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-devel-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-libs-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-relay");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-relay-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:dhcp-server-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alibabacloud:alibaba_cloud_linux_3");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Alibaba Cloud Linux 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/Alibaba/release", "Host/Alibaba/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Alibaba/release');
if (isnull(os_release) || 'Alibaba Cloud Linux' >!< os_release) audit(AUDIT_OS_NOT, 'Alibaba Cloud Linux');
var os_ver = pregmatch(pattern: "Alibaba Cloud Linux release ([0-9]+(\.[0-9]+)?)", string:os_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Alibaba Cloud Linux');
os_ver = os_ver[1];
if (! preg(pattern:"^3([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Alibaba Cloud Linux 3.x', 'Alibaba Cloud Linux ' + os_ver);

if (!get_kb_item('Host/Alibaba/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('aarch64' >!< cpu && 'x86_64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Alibaba Cloud Linux', cpu);

var pkgs = [
    {'reference':'dhcp-client-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-client-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-client-debuginfo-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-client-debuginfo-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-common-4.3.6-44.3.al8.1', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-debuginfo-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-debuginfo-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-debugsource-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-debugsource-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-devel-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-devel-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-devel-doc-4.3.6-44.3.al8.1', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-libs-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-libs-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-libs-debuginfo-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-libs-debuginfo-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-relay-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-relay-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-relay-debuginfo-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-relay-debuginfo-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-server-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-server-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-server-debuginfo-4.3.6-44.3.al8.1', 'cpu':'aarch64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'},
    {'reference':'dhcp-server-debuginfo-4.3.6-44.3.al8.1', 'cpu':'x86_64', 'release':'3', 'rpm_spec_vers_cmp':TRUE, 'epoch':'0'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  var cves = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = 'Alibaba Linux ' + package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_NOTE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'dhcp-client / dhcp-client-debuginfo / dhcp-common / dhcp-debuginfo / etc');
}