Ubuntu 16.04 LTS : Linux kernel vulnerabilities (USN-4427-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4427-1. 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(138836);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2019-12380",
    "CVE-2019-19947",
    "CVE-2019-20810",
    "CVE-2019-20908",
    "CVE-2020-10732",
    "CVE-2020-10766",
    "CVE-2020-10767",
    "CVE-2020-10768",
    "CVE-2020-11935",
    "CVE-2020-13974"
  );
  script_xref(name:"USN", value:"4427-1");

  script_name(english:"Ubuntu 16.04 LTS : Linux kernel vulnerabilities (USN-4427-1)");

  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-4427-1 advisory.

  - **DISPUTED** An issue was discovered in the efi subsystem in the Linux kernel through 5.1.5.
    phys_efi_set_virtual_address_map in arch/x86/platform/efi/efi.c and efi_call_phys_prolog in
    arch/x86/platform/efi/efi_64.c mishandle memory allocation failures. NOTE: This id is disputed as not
    being an issue because All the code touched by the referenced commit runs only at boot, before any user
    processes are started. Therefore, there is no possibility for an unprivileged user to control it..
    (CVE-2019-12380)

  - In the Linux kernel through 5.4.6, there are information leaks of uninitialized memory to a USB device in
    the drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c driver, aka CID-da2311a6385c. (CVE-2019-19947)

  - go7007_snd_init in drivers/media/usb/go7007/snd-go7007.c in the Linux kernel before 5.6 does not call
    snd_card_free for a failure path, which causes a memory leak, aka CID-9453264ef586. (CVE-2019-20810)

  - An issue was discovered in drivers/firmware/efi/efi.c in the Linux kernel before 5.4. Incorrect access
    permissions for the efivar_ssdt ACPI variable could be used by attackers to bypass lockdown or secure boot
    restrictions, aka CID-1957a85b0032. (CVE-2019-20908)

  - A flaw was found in the Linux kernel's implementation of Userspace core dumps. This flaw allows an
    attacker with a local account to crash a trivial program and exfiltrate private kernel data.
    (CVE-2020-10732)

  - A logic bug flaw was found in Linux kernel before 5.8-rc1 in the implementation of SSBD. A bug in the
    logic handling allows an attacker with a local account to disable SSBD protection during a context switch
    when additional speculative execution mitigations are in place. This issue was introduced when the per
    task/process conditional STIPB switching was added on top of the existing SSBD switching. The highest
    threat from this vulnerability is to confidentiality. (CVE-2020-10766)

  - A flaw was found in the Linux kernel before 5.8-rc1 in the implementation of the Enhanced IBPB (Indirect
    Branch Prediction Barrier). The IBPB mitigation will be disabled when STIBP is not available or when the
    Enhanced Indirect Branch Restricted Speculation (IBRS) is available. This flaw allows a local attacker to
    perform a Spectre V2 style attack when this configuration is active. The highest threat from this
    vulnerability is to confidentiality. (CVE-2020-10767)

  - A flaw was found in the Linux Kernel before 5.8-rc1 in the prctl() function, where it can be used to
    enable indirect branch speculation after it has been disabled. This call incorrectly reports it as being
    'force disabled' when it is not and opens the system to Spectre v2 attacks. The highest threat from this
    vulnerability is to confidentiality. (CVE-2020-10768)

  - It was discovered that aufs improperly managed inode reference counts in the vfsub_dentry_open() method. A
    local attacker could use this vulnerability to cause a denial of service attack. (CVE-2020-11935)

  - An issue was discovered in the Linux kernel 4.4 through 5.7.1. drivers/tty/vt/keyboard.c has an integer
    overflow if k_ascii is called several times in a row, aka CID-b86dab054059. NOTE: Members in the community
    argue that the integer overflow does not lead to a security issue in this case. (CVE-2020-13974)

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-4427-1");
  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:POC/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:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-13974");

  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:"2019/05/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/07/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/07/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1077-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1111-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1136-raspi2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1140-snapdragon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-lowlatency");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc-e500mc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc-smp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc64-emb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc64-smp");
  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) 2020-2024 Canonical, Inc. / NASL script (C) 2020-2024 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': {
    '4.4.0': {
      'generic': '4.4.0-186',
      'generic-lpae': '4.4.0-186',
      'lowlatency': '4.4.0-186',
      'powerpc-e500mc': '4.4.0-186',
      'powerpc-smp': '4.4.0-186',
      'powerpc64-emb': '4.4.0-186',
      'powerpc64-smp': '4.4.0-186',
      'kvm': '4.4.0-1077',
      'aws': '4.4.0-1111',
      'raspi2': '4.4.0-1136',
      'snapdragon': '4.4.0-1140'
    }
  }
};

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-4427-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2019-12380', 'CVE-2019-19947', 'CVE-2019-20810', 'CVE-2019-20908', 'CVE-2020-10732', 'CVE-2020-10766', 'CVE-2020-10767', 'CVE-2020-10768', 'CVE-2020-11935', 'CVE-2020-13974');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4427-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}