TencentOS Server 3: dhcp (TSSA-2022:0201)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Tencent Linux Security Advisory TSSA-2022:0201.
##

include('compat.inc');

if (description)
{
  script_id(276373);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/21");

  script_cve_id("CVE-2021-25217");
  script_xref(name:"IAVB", value:"2021-B-0032-S");

  script_name(english:"TencentOS Server 3: dhcp (TSSA-2022:0201)");

  script_set_attribute(attribute:"synopsis", value:
"The remote TencentOS Server 3 host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is,
therefore, affected by a vulnerability as referenced in the TSSA-2022:0201 advisory.

    Package updates are available for TencentOS Server 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 Tencent 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:"https://mirrors.tencent.com/tlinux/errata/tssa-20220201.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:"2022/12/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/11/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:tencent:tencentos_server:3");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:tencent:tencentos_server:dhcp");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2025-2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/etc/os-release", "Host/TencentOS/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm2.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'TencentOS' >!< os_product) audit(AUDIT_OS_NOT, 'TencentOS');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'TencentOS');
if (! preg(pattern:"^3([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'TencentOS 3.x', 'TencentOS ' + os_version);

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

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'TencentOS', cpu);

var constraints = [
  {
    'release': '3',
    'pkgs': [
      {'reference':'dhcp-client-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-client-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-client-debuginfo-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-client-debuginfo-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-common-4.3.6-47.tl3.2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-debuginfo-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-debuginfo-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-debugsource-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-debugsource-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-devel-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-devel-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-devel-doc-4.3.6-47.tl3.2', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-libs-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-libs-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-libs-debuginfo-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-libs-debuginfo-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-relay-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-relay-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-relay-debuginfo-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-relay-debuginfo-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-server-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-server-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-server-debuginfo-4.3.6-47.tl3.2', 'cpu':'aarch64', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'dhcp-server-debuginfo-4.3.6-47.tl3.2', 'cpu':'x86_64', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(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 / etc');
}