Ubuntu 16.04 LTS / 18.04 LTS : Net-SNMP regression (USN-4471-2)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4471-2. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include('compat.inc');

if (description)
{
  script_id(140176);
  script_version("1.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/20");

  script_cve_id("CVE-2020-15861", "CVE-2020-15862");
  script_xref(name:"USN", value:"4471-2");
  script_xref(name:"IAVA", value:"2020-A-0384-S");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS : Net-SNMP regression (USN-4471-2)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"USN-4471-1 fixed a vulnerability in Net-SNMP. The updated introduced a
regression making nsExtendCacheTime not settable. This update fixes
the problem adding the cacheTime feature flag.

Tobias Neitzel discovered that Net-SNMP incorrectly handled certain
symlinks. An attacker could possibly use this issue to access
sensitive information. (CVE-2020-15861) It was discovered that
Net-SNMP incorrectly handled certain inputs. An attacker could
possibly use this issue to execute arbitrary code. This issue only
affected Ubuntu 14.04 ESM, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and
Ubuntu 20.04 LTS. (CVE-2020-15862).

Note that Tenable Network Security has extracted the preceding
description block directly from the Ubuntu security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-4471-2");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-15862");

  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:"2020/08/20");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/09/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/09/02");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsnmp-base");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsnmp-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsnmp-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsnmp30");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python-netsnmp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snmp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snmpd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snmptrapd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:tkmib");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  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:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2020-2023 Canonical, Inc. / NASL script (C) 2020-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/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);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('16.04' >< os_release || '18.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 18.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) 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, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '16.04', 'pkgname': 'libsnmp-base', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'libsnmp-dev', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'libsnmp-perl', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'libsnmp30', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'python-netsnmp', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'snmp', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'snmpd', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'snmptrapd', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '16.04', 'pkgname': 'tkmib', 'pkgver': '5.7.3+dfsg-1ubuntu4.6'},
    {'osver': '18.04', 'pkgname': 'libsnmp-base', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'libsnmp-dev', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'libsnmp-perl', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'libsnmp30', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'python-netsnmp', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'snmp', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'snmpd', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'snmptrapd', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'},
    {'osver': '18.04', 'pkgname': 'tkmib', 'pkgver': '5.7.3+dfsg-1.8ubuntu3.6'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libsnmp-base / libsnmp-dev / libsnmp-perl / libsnmp30 / etc');
}