Oracle Linux 6 / 7 : Unbreakable Enterprise kernel (ELSA-2021-9009)

2021-01-13T00:00:00
ID ORACLELINUX_ELSA-2021-9009.NASL
Type nessus
Reporter This script is Copyright (C) 2021 and is owned by Tenable, Inc. or an Affiliate thereof.
Modified 2021-01-13T00:00:00

Description

The remote Oracle Linux 6 / 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2021-9009 advisory.

  • An issue was discovered in the Linux kernel through 5.9.1, as used with Xen through 4.14.x. Guest OS users can cause a denial of service (host OS hang) via a high rate of events to dom0, aka CID-e99502f76271. (CVE-2020-27673)

  • An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are processing watch events using a single thread. If the events are received faster than the thread is able to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable. (CVE-2020-29568)

  • An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback. (CVE-2020-29569)

  • In drivers/target/target_core_xcopy.c in the Linux kernel before 5.10.7, insufficient identifier checking in the LIO SCSI target code can be used by remote attackers to read or write files via directory traversal in an XCOPY request, aka CID-2896c93811e3. For example, an attack can occur over a network if the attacker has access to one iSCSI LUN. The attacker gains control over file access because I/O operations are proxied via an attacker-selected backstore. (CVE-2020-28374)

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 Oracle Linux Security Advisory ELSA-2021-9009.
##

include('compat.inc');

if (description)
{
  script_id(144905);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/01/13");

  script_cve_id(
    "CVE-2020-27673",
    "CVE-2020-28374",
    "CVE-2020-29568",
    "CVE-2020-29569"
  );

  script_name(english:"Oracle Linux 6 / 7 : Unbreakable Enterprise kernel (ELSA-2021-9009)");
  script_summary(english:"Checks the rpm output for the updated packages");

  script_set_attribute(attribute:"synopsis", value:
"The remote Oracle Linux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Oracle Linux 6 / 7 host has packages installed that are affected by multiple vulnerabilities as referenced in
the ELSA-2021-9009 advisory.

  - An issue was discovered in the Linux kernel through 5.9.1, as used with Xen through 4.14.x. Guest OS users
    can cause a denial of service (host OS hang) via a high rate of events to dom0, aka CID-e99502f76271.
    (CVE-2020-27673)

  - An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are
    processing watch events using a single thread. If the events are received faster than the thread is able
    to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the
    backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable. (CVE-2020-29568)

  - An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux
    kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped.
    However, the handler may not have time to run if the frontend quickly toggles between the states connect
    and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving
    guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege
    escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.
    (CVE-2020-29569)

  - In drivers/target/target_core_xcopy.c in the Linux kernel before 5.10.7, insufficient identifier checking
    in the LIO SCSI target code can be used by remote attackers to read or write files via directory traversal
    in an XCOPY request, aka CID-2896c93811e3. For example, an attack can occur over a network if the attacker
    has access to one iSCSI LUN. The attacker gains control over file access because I/O operations are
    proxied via an attacker-selected backstore. (CVE-2020-28374)

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://linux.oracle.com/errata/ELSA-2021-9009.html");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  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:L/UI:N/S:C/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-2020-29569");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/10/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/01/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/01/13");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:6");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek-debug");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek-debug-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:kernel-uek-firmware");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Oracle Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2021 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("linux_alt_patch_detect.nasl", "ssh_get_info.nasl");
  script_require_keys("Host/OracleLinux", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/local_checks_enabled");

  exit(0);
}


include('audit.inc');
include('global_settings.inc');
include('ksplice.inc');
include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item('Host/OracleLinux')) audit(AUDIT_OS_NOT, 'Oracle Linux');
release = get_kb_item("Host/RedHat/release");
if (isnull(release) || !pregmatch(pattern: "Oracle (?:Linux Server|Enterprise Linux)", string:release)) audit(AUDIT_OS_NOT, 'Oracle Linux');
os_ver = pregmatch(pattern: "Oracle (?:Linux Server|Enterprise Linux) .*release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Oracle Linux');
os_ver = os_ver[1];
if (! preg(pattern:"^(6|7)([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Oracle Linux 6 / 7', 'Oracle Linux ' + os_ver);

if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Oracle Linux', cpu);
if ('x86_64' >!< cpu) audit(AUDIT_ARCH_NOT, 'x86_64', cpu);

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  rm_kb_item(name:'Host/uptrack-uname-r');
  cve_list = make_list('CVE-2020-27673', 'CVE-2020-28374', 'CVE-2020-29568', 'CVE-2020-29569');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for ELSA-2021-9009');
  }
  else
  {
    __rpm_report = ksplice_reporting_text();
  }
}

kernel_major_minor = get_kb_item('Host/uname/major_minor');
if (empty_or_null(kernel_major_minor)) exit(1, 'Unable to determine kernel major-minor level.');
expected_kernel_major_minor = '4.1';
if (kernel_major_minor != expected_kernel_major_minor)
  audit(AUDIT_OS_NOT, 'running kernel level ' + expected_kernel_major_minor + ', it is running kernel level ' + kernel_major_minor);

pkgs = [
    {'reference':'kernel-uek-4.1.12-124.46.4.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_prefix':'kernel-uek-4.1.12'},
    {'reference':'kernel-uek-debug-4.1.12-124.46.4.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_prefix':'kernel-uek-debug-4.1.12'},
    {'reference':'kernel-uek-debug-devel-4.1.12-124.46.4.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_prefix':'kernel-uek-debug-devel-4.1.12'},
    {'reference':'kernel-uek-devel-4.1.12-124.46.4.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_prefix':'kernel-uek-devel-4.1.12'},
    {'reference':'kernel-uek-doc-4.1.12-124.46.4.1.el6uek', 'release':'6', 'rpm_prefix':'kernel-uek-doc-4.1.12'},
    {'reference':'kernel-uek-firmware-4.1.12-124.46.4.1.el6uek', 'release':'6', 'rpm_prefix':'kernel-uek-firmware-4.1.12'},
    {'reference':'kernel-uek-4.1.12-124.46.4.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_prefix':'kernel-uek-4.1.12'},
    {'reference':'kernel-uek-debug-4.1.12-124.46.4.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_prefix':'kernel-uek-debug-4.1.12'},
    {'reference':'kernel-uek-debug-devel-4.1.12-124.46.4.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_prefix':'kernel-uek-debug-devel-4.1.12'},
    {'reference':'kernel-uek-devel-4.1.12-124.46.4.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_prefix':'kernel-uek-devel-4.1.12'},
    {'reference':'kernel-uek-doc-4.1.12-124.46.4.1.el7uek', 'release':'7', 'rpm_prefix':'kernel-uek-doc-4.1.12'},
    {'reference':'kernel-uek-firmware-4.1.12-124.46.4.1.el7uek', 'release':'7', 'rpm_prefix':'kernel-uek-firmware-4.1.12'}
];

flag = 0;
foreach package_array ( pkgs ) {
  reference = NULL;
  release = NULL;
  sp = NULL;
  cpu = NULL;
  el_string = NULL;
  rpm_spec_vers_cmp = NULL;
  epoch = NULL;
  allowmaj = NULL;
  rpm_prefix = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = 'EL' + package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['rpm_prefix'])) rpm_prefix = package_array['rpm_prefix'];
  if (reference && release) {
    if (rpm_prefix) {
        if (rpm_exists(release:release, rpm:rpm_prefix) && rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
    } else {
        if (rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
    }
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'kernel-uek / kernel-uek-debug / kernel-uek-debug-devel / etc');
}