Linux Distros Unpatched Vulnerability : CVE-2020-27749

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(223522);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/09/03");

  script_cve_id("CVE-2020-27749");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2020-27749");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied
    command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage,
    without sufficient bounds checking. If the function is called with a command line that references a
    variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack
    frame and control execution which could also circumvent Secure Boot protections. The highest threat from
    this vulnerability is to data confidentiality and integrity as well as system availability.
    (CVE-2020-27749)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2020-27749");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2020-27749");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  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: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-2020-27749");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/07/30");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/03/04");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:7");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:grub2-signed");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupd-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupdate");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupdate-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupdate-efi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:fwupdate-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupd-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupdate");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupdate-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupdate-efi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:fwupdate-libs");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("set_linux_os_id.nasl", "ssh_get_info2.nasl");
  script_require_keys("Host/OS/identifier", "Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched");
  script_require_ports("Host/OS/CentOS Linux-7", "Host/OS/Red Hat Enterprise Linux-7", "Host/OS/Ubuntu Linux-14.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/CentOS/rpm-list")) && empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "grub-efi-amd64-signed"}
        ]
      }
    ]
  },
  "CentOS Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "fwupd"},
          {"reference": "fwupd-devel"},
          {"reference": "fwupdate"},
          {"reference": "fwupdate-devel"},
          {"reference": "fwupdate-efi"},
          {"reference": "fwupdate-libs"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-7": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "7",
        "pkgs": [
          {"reference": "fwupd"},
          {"reference": "fwupd-devel"},
          {"reference": "fwupdate"},
          {"reference": "fwupdate-devel"},
          {"reference": "fwupdate-efi"},
          {"reference": "fwupdate-libs"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');
var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}