Ubuntu 14.04 LTS / 16.04 LTS : Bash vulnerabilities (USN-3294-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3294-1. 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(100268);
  script_version("3.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/20");

  script_cve_id(
    "CVE-2016-0634",
    "CVE-2016-7543",
    "CVE-2016-9401",
    "CVE-2017-5932"
  );
  script_xref(name:"USN", value:"3294-1");

  script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS : Bash vulnerabilities (USN-3294-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"Bernd Dietzel discovered that Bash incorrectly expanded the hostname
when displaying the prompt. If a remote attacker were able to modify a
hostname, this flaw could be exploited to execute arbitrary code. This
issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu
16.10. (CVE-2016-0634)

It was discovered that Bash incorrectly handled the SHELLOPTS and PS4
environment variables. A local attacker could use this issue to
execute arbitrary code with root privileges. This issue only affected
Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2016-7543)

It was discovered that Bash incorrectly handled the popd command. A
remote attacker could possibly use this issue to bypass restricted
shells. (CVE-2016-9401)

It was discovered that Bash incorrectly handled path autocompletion. A
local attacker could possibly use this issue to execute arbitrary
code. This issue only affected Ubuntu 17.04. (CVE-2017-5932).

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-3294-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected bash, bash-builtins and / or bash-static 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:N/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-2016-7543");

  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:"2017/01/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/05/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/05/18");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:bash");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:bash-builtins");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:bash-static");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  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) 2017-2023 Canonical, Inc. / NASL script (C) 2017-2023 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 (! ('14.04' >< os_release || '16.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 14.04 / 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': '14.04', 'pkgname': 'bash', 'pkgver': '4.3-7ubuntu1.7'},
    {'osver': '14.04', 'pkgname': 'bash-builtins', 'pkgver': '4.3-7ubuntu1.7'},
    {'osver': '14.04', 'pkgname': 'bash-static', 'pkgver': '4.3-7ubuntu1.7'},
    {'osver': '16.04', 'pkgname': 'bash', 'pkgver': '4.3-14ubuntu1.2'},
    {'osver': '16.04', 'pkgname': 'bash-builtins', 'pkgver': '4.3-14ubuntu1.2'},
    {'osver': '16.04', 'pkgname': 'bash-static', 'pkgver': '4.3-14ubuntu1.2'}
];

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, 'bash / bash-builtins / bash-static');
}