CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:P/I:P/A:C
CVSS3
Attack Vector
PHYSICAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H
AI Score
Confidence
High
EPSS
Percentile
5.1%
The remote Ubuntu 20.04 LTS host has a package installed that is affected by a vulnerability as referenced in the USN-4683-1 advisory.
Minh Yuan discovered that the framebuffer console driver in the Linux kernel did not properly handle fonts in some conditions. A local attacker could use this to cause a denial of service (system crash) or possibly expose sensitive information (kernel memory).
Tenable has extracted the preceding description block directly from the Ubuntu security advisory.
Note that Nessus has not tested for this issue 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-4683-1. 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(144786);
script_version("1.8");
script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");
script_cve_id("CVE-2020-28974");
script_xref(name:"USN", value:"4683-1");
script_name(english:"Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerability (USN-4683-1)");
script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing a security update.");
script_set_attribute(attribute:"description", value:
"The remote Ubuntu 20.04 LTS host has a package installed that is affected by a vulnerability as referenced in the
USN-4683-1 advisory.
Minh Yuan discovered that the framebuffer console driver in the Linux kernel did not properly handle fonts
in some conditions. A local attacker could use this to cause a denial of service (system crash) or
possibly expose sensitive information (kernel memory).
Tenable has extracted the preceding description block directly from the Ubuntu security advisory.
Note that Nessus has not tested for this issue 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-4683-1");
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:C");
script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
script_set_cvss3_base_vector("CVSS:3.0/AV:P/AC:L/PR:H/UI:N/S:U/C:L/I:L/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-2020-28974");
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:"2020/11/19");
script_set_attribute(attribute:"patch_publication_date", value:"2021/01/07");
script_set_attribute(attribute:"plugin_publication_date", value:"2021/01/07");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.6.0-1039-oem");
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) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 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 (! ('20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 20.04', '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 = {
'20.04': {
'5.6.0': {
'oem': '5.6.0-1039'
}
}
};
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 += '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-4683-1');
}
if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
var cve_list = make_list('CVE-2020-28974');
if (ksplice_cves_check(cve_list))
{
audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4683-1');
}
else
{
extra = extra + ksplice_reporting_text();
}
}
if (extra) {
security_report_v4(
port : 0,
severity : SECURITY_WARNING,
extra : extra
);
exit(0);
}
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:P/I:P/A:C
CVSS3
Attack Vector
PHYSICAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H
AI Score
Confidence
High
EPSS
Percentile
5.1%