Ubuntu 16.04 LTS : systemd regression (USN-3816-3)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3816-3. 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(119253);
  script_version("1.11");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/20");

  script_cve_id("CVE-2018-15686", "CVE-2018-15687", "CVE-2018-6954");
  script_xref(name:"USN", value:"3816-3");

  script_name(english:"Ubuntu 16.04 LTS : systemd regression (USN-3816-3)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"USN-3816-1 fixed vulnerabilities in systemd. The fix for CVE-2018-6954
caused a regression in systemd-tmpfiles when running Ubuntu inside a
container on some older kernels. This issue only affected Ubuntu 16.04
LTS. In order to continue to support this configuration, the fixes for
CVE-2018-6954 have been reverted.

We apologize for the inconvenience.

Jann Horn discovered that unit_deserialize incorrectly handled status
messages above a certain length. A local attacker could potentially
exploit this via NotifyAccess to inject arbitrary state across
re-execution and obtain root privileges. (CVE-2018-15686)

Jann Horn discovered a race condition in chown_one(). A local attacker
could potentially exploit this by setting arbitrary permissions on
certain files to obtain root privileges. This issue only affected
Ubuntu 18.04 LTS and Ubuntu 18.10. (CVE-2018-15687)

It was discovered that systemd-tmpfiles mishandled symlinks in
non-terminal path components. A local attacker could potentially
exploit this by gaining ownership of certain files to obtain root
privileges. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04
LTS. (CVE-2018-6954).

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-3816-3");
  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:F/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:F/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2018-6954");

  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:"2018/02/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2018/11/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/11/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:systemd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:systemd-container");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:systemd-coredump");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:systemd-journal-remote");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:systemd-sysv");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:udev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:udev-udeb");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libnss-myhostname");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libnss-mymachines");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libnss-resolve");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpam-systemd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsystemd-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsystemd0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libudev-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libudev1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libudev1-udeb");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2018-2023 Canonical, Inc. / NASL script (C) 2018-2023 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)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04', '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': 'libnss-myhostname', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libnss-mymachines', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libnss-resolve', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libpam-systemd', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libsystemd-dev', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libsystemd0', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libudev-dev', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libudev1', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'libudev1-udeb', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'systemd', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'systemd-container', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'systemd-coredump', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'systemd-journal-remote', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'systemd-sysv', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'udev', 'pkgver': '229-4ubuntu21.10'},
    {'osver': '16.04', 'pkgname': 'udev-udeb', 'pkgver': '229-4ubuntu21.10'}
];

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, 'libnss-myhostname / libnss-mymachines / libnss-resolve / etc');
}