Ubuntu 16.04 LTS : Linux kernel (GCP) vulnerabilities (USN-3507-2)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3507-2. 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(105101);
  script_version("3.13");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2017-1000405",
    "CVE-2017-12193",
    "CVE-2017-15299",
    "CVE-2017-15306",
    "CVE-2017-15951",
    "CVE-2017-16939"
  );
  script_xref(name:"USN", value:"3507-2");

  script_name(english:"Ubuntu 16.04 LTS : Linux kernel (GCP) vulnerabilities (USN-3507-2)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-3507-2 advisory.

  - The Linux Kernel versions 2.6.38 through 4.14 have a problematic use of pmd_mkdirty() in the touch_pmd()
    function inside the THP implementation. touch_pmd() can be reached by get_user_pages(). In such case, the
    pmd will become dirty. This scenario breaks the new can_follow_write_pmd()'s logic - pmd can become dirty
    without going through a COW cycle. This bug is not as severe as the original Dirty cow because an ext4
    file (or any other regular file) cannot be mapped using THP. Nevertheless, it does allow us to overwrite
    read-only huge pages. For example, the zero huge page and sealed shmem files can be overwritten (since
    their mapping can be populated using THP). Note that after the first write page-fault to the zero page, it
    will be replaced with a new fresh (and zeroed) thp. (CVE-2017-1000405)

  - The assoc_array_insert_into_terminal_node function in lib/assoc_array.c in the Linux kernel before 4.13.11
    mishandles node splitting, which allows local users to cause a denial of service (NULL pointer dereference
    and panic) via a crafted application, as demonstrated by the keyring key type, and key addition and link
    creation operations. (CVE-2017-12193)

  - The KEYS subsystem in the Linux kernel through 4.13.7 mishandles use of add_key for a key that already
    exists but is uninstantiated, which allows local users to cause a denial of service (NULL pointer
    dereference and system crash) or possibly have unspecified other impact via a crafted system call.
    (CVE-2017-15299)

  - The kvm_vm_ioctl_check_extension function in arch/powerpc/kvm/powerpc.c in the Linux kernel before 4.13.11
    allows local users to cause a denial of service (NULL pointer dereference and system crash) via a
    KVM_CHECK_EXTENSION KVM_CAP_PPC_HTM ioctl call to /dev/kvm. (CVE-2017-15306)

  - The KEYS subsystem in the Linux kernel before 4.13.10 does not correctly synchronize the actions of
    updating versus finding a key in the negative state to avoid a race condition, which allows local users
    to cause a denial of service or possibly have unspecified other impact via crafted system calls.
    (CVE-2017-15951)

  - The XFRM dump policy implementation in net/xfrm/xfrm_user.c in the Linux kernel before 4.13.11 allows
    local users to gain privileges or cause a denial of service (use-after-free) via a crafted SO_RCVBUF
    setsockopt system call in conjunction with XFRM_MSG_GETPOLICY Netlink messages. (CVE-2017-16939)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-3507-2");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  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:H/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:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2017-16939");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"exploited_by_malware", value:"true");
  script_set_attribute(attribute:"in_the_news", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2017/10/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/12/07");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/12/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.13.0-1002-gcp");
  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) 2017-2024 Canonical, Inc. / NASL script (C) 2017-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');
include('ksplice.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 kernel_mappings = {
  '16.04': {
    '4.13.0': {
      'gcp': '4.13.0-1002'
    }
  }
};

var host_kernel_release = get_kb_item('Host/uptrack-uname-r');
if (empty_or_null(host_kernel_release)) host_kernel_release = get_kb_item_or_exit('Host/uname-r');
var host_kernel_base_version = get_kb_item_or_exit('Host/Debian/kernel-base-version');
var host_kernel_type = get_kb_item_or_exit('Host/Debian/kernel-type');
if(empty_or_null(kernel_mappings[os_release][host_kernel_base_version][host_kernel_type])) audit(AUDIT_INST_VER_NOT_VULN, 'kernel ' + host_kernel_release);

var extra = '';
var kernel_fixed_version = kernel_mappings[os_release][host_kernel_base_version][host_kernel_type] + "-" + host_kernel_type;
if (deb_ver_cmp(ver1:host_kernel_release, ver2:kernel_fixed_version) < 0)
{
  extra = extra + 'Running Kernel level of ' + host_kernel_release + ' does not meet the minimum fixed level of ' + kernel_fixed_version + ' for this advisory.\n\n';
}
  else
{
  audit(AUDIT_PATCH_INSTALLED, 'Kernel package for USN-3507-2');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2017-12193', 'CVE-2017-15299', 'CVE-2017-15306', 'CVE-2017-15951', 'CVE-2017-16939', 'CVE-2017-1000405');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-3507-2');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}