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Ubuntu Security Notice (C) 2020-2024 Canonical, Inc. / NASL script (C) 2020-2024 and is owned by Tenable, Inc. or an Affiliate thereof.UBUNTU_USN-4412-1.NASL
HistoryJul 06, 2020 - 12:00 a.m.

Ubuntu 18.04 LTS : Linux kernel vulnerabilities (USN-4412-1)

2020-07-0600:00:00
Ubuntu Security Notice (C) 2020-2024 Canonical, Inc. / NASL script (C) 2020-2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
23

7.2 High

AI Score

Confidence

Low

The remote Ubuntu 18.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4412-1 advisory.

  • A NULL pointer dereference flaw was found in the Linux kernel’s SELinux subsystem in versions before 5.7.
    This flaw occurs while importing the Commercial IP Security Option (CIPSO) protocol’s category bitmap into the SELinux extensible bitmap via the’ ebitmap_netlbl_import’ routine. While processing the CIPSO restricted bitmap tag in the ‘cipso_v4_parsetag_rbm’ routine, it sets the security attribute to indicate that the category bitmap is present, even if it has not been allocated. This issue leads to a NULL pointer dereference issue while importing the same category bitmap into SELinux. This flaw allows a remote network user to crash the system kernel, resulting in a denial of service. (CVE-2020-10711)

  • A flaw was found in the Linux kernels SELinux LSM hook implementation before version 5.7, where it incorrectly assumed that an skb would only contain a single netlink message. The hook would incorrectly only validate the first netlink message in the skb and allow or deny the rest of the messages within the skb with the granted permission without further processing. (CVE-2020-10751)

  • An issue was discovered in the Linux kernel before 5.6. svm_cpu_uninit in arch/x86/kvm/svm.c has a memory leak, aka CID-d80b64ff297e. NOTE: third parties dispute this issue because it’s a one-time leak at the boot, the size is negligible, and it can’t be triggered at will (CVE-2020-12768)

  • An issue was discovered in the Linux kernel through 5.6.11. sg_write lacks an sg_remove_request call in a certain failure case, aka CID-83c6f2390040. (CVE-2020-12770)

  • gadget_dev_desc_UDC_store in drivers/usb/gadget/configfs.c in the Linux kernel 3.16 through 5.6.13 relies on kstrdup without considering the possibility of an internal ‘\0’ value, which allows attackers to trigger an out-of-bounds read, aka CID-15753588bcd4. (CVE-2020-13143)

Note that Nessus has not tested for these issues but has instead relied only on the application’s self-reported version number.

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4412-1. 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(138137);
  script_version("1.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2020-10711",
    "CVE-2020-10751",
    "CVE-2020-12768",
    "CVE-2020-12770",
    "CVE-2020-13143"
  );
  script_xref(name:"USN", value:"4412-1");

  script_name(english:"Ubuntu 18.04 LTS : Linux kernel vulnerabilities (USN-4412-1)");

  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 18.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-4412-1 advisory.

  - A NULL pointer dereference flaw was found in the Linux kernel's SELinux subsystem in versions before 5.7.
    This flaw occurs while importing the Commercial IP Security Option (CIPSO) protocol's category bitmap into
    the SELinux extensible bitmap via the' ebitmap_netlbl_import' routine. While processing the CIPSO
    restricted bitmap tag in the 'cipso_v4_parsetag_rbm' routine, it sets the security attribute to indicate
    that the category bitmap is present, even if it has not been allocated. This issue leads to a NULL pointer
    dereference issue while importing the same category bitmap into SELinux. This flaw allows a remote network
    user to crash the system kernel, resulting in a denial of service. (CVE-2020-10711)

  - A flaw was found in the Linux kernels SELinux LSM hook implementation before version 5.7, where it
    incorrectly assumed that an skb would only contain a single netlink message. The hook would incorrectly
    only validate the first netlink message in the skb and allow or deny the rest of the messages within the
    skb with the granted permission without further processing. (CVE-2020-10751)

  - An issue was discovered in the Linux kernel before 5.6. svm_cpu_uninit in arch/x86/kvm/svm.c has a memory
    leak, aka CID-d80b64ff297e. NOTE: third parties dispute this issue because it's a one-time leak at the
    boot, the size is negligible, and it can't be triggered at will (CVE-2020-12768)

  - An issue was discovered in the Linux kernel through 5.6.11. sg_write lacks an sg_remove_request call in a
    certain failure case, aka CID-83c6f2390040. (CVE-2020-12770)

  - gadget_dev_desc_UDC_store in drivers/usb/gadget/configfs.c in the Linux kernel 3.16 through 5.6.13 relies
    on kstrdup without considering the possibility of an internal '\0' value, which allows attackers to
    trigger an out-of-bounds read, aka CID-15753588bcd4. (CVE-2020-13143)

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-4412-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:P/I:P/A:P");
  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:H/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-2020-12770");

  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:"2020/05/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/07/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/07/06");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1028-raspi2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1030-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1030-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1030-gke");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1032-azure");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-62-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-62-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-62-lowlatency");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-: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 (! ('18.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 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 kernel_mappings = {
  '18.04': {
    '5.3.0': {
      'generic': '5.3.0-62',
      'generic-lpae': '5.3.0-62',
      'lowlatency': '5.3.0-62',
      'raspi2': '5.3.0-1028',
      'aws': '5.3.0-1030',
      'gcp': '5.3.0-1030',
      'gke': '5.3.0-1030',
      'azure': '5.3.0-1032'
    }
  }
};

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-4412-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2020-10711', 'CVE-2020-10751', 'CVE-2020-12768', 'CVE-2020-12770', 'CVE-2020-13143');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4412-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}
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7.2 High

AI Score

Confidence

Low

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