CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
14.2%
The remote Oracle Linux 6 / 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2021-9051 advisory.
An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn’t mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c. (CVE-2021-26930)
An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it isn’t correct to assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.
(CVE-2021-26931)
An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen. Grant mapping operations often occur in batch hypercalls, where a number of operations are done in a single hypercall, the success or failure of each one is reported to the backend driver, and the backend driver then loops over the results, performing follow-up actions based on the success or failure of each operation. Unfortunately, when running in PV mode, the Linux backend drivers mishandle this: Some errors are ignored, effectively implying their success from the success of related batch elements. In other cases, errors resulting from one batch element lead to further batch elements not being inspected, and hence successful ones to not be possible to properly unmap upon error recovery. Only systems with Linux backends running in PV mode are vulnerable. Linux backends run in HVM / PVH modes are not vulnerable. This affects arch/*/xen/p2m.c and drivers/xen/gntdev.c. (CVE-2021-26932)
Note that Nessus has not tested for this issue but has instead relied only on the application’s self-reported version number.
#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Oracle Linux Security Advisory ELSA-2021-9051.
##
include('deprecated_nasl_level.inc');
include('compat.inc');
if (description)
{
script_id(148546);
script_version("1.3");
script_set_attribute(attribute:"plugin_modification_date", value:"2021/09/08");
script_cve_id("CVE-2021-26930", "CVE-2021-26931", "CVE-2021-26932");
script_name(english:"Oracle Linux 6 / 7 : Unbreakable Enterprise kernel (ELSA-2021-9051)");
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-2021-9051 advisory.
- An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to
the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be
encountered. In one case, an error encountered earlier might be discarded by later processing, resulting
in the caller assuming successful mapping, and hence subsequent operations trying to access space that
wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery
from the error. This affects drivers/block/xen-blkback/blkback.c. (CVE-2021-26930)
- An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI
backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially
being at least under the influence of guests (such as out of memory conditions), it isn't correct to
assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running
in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.
(CVE-2021-26931)
- An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen. Grant mapping operations
often occur in batch hypercalls, where a number of operations are done in a single hypercall, the success
or failure of each one is reported to the backend driver, and the backend driver then loops over the
results, performing follow-up actions based on the success or failure of each operation. Unfortunately,
when running in PV mode, the Linux backend drivers mishandle this: Some errors are ignored, effectively
implying their success from the success of related batch elements. In other cases, errors resulting from
one batch element lead to further batch elements not being inspected, and hence successful ones to not be
possible to properly unmap upon error recovery. Only systems with Linux backends running in PV mode are
vulnerable. Linux backends run in HVM / PVH modes are not vulnerable. This affects arch/*/xen/p2m.c and
drivers/xen/gntdev.c. (CVE-2021-26932)
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-2021-9051.html");
script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
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:L/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-2021-26930");
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:"2021/02/16");
script_set_attribute(attribute:"patch_publication_date", value:"2021/02/16");
script_set_attribute(attribute:"plugin_publication_date", value:"2021/04/14");
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');
var 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');
var 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');
var os_ver = os_ver[1];
if (! preg(pattern:"^(6|7)([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Oracle Linux 6 / 7', 'Oracle Linux ' + os_ver);
if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);
var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Oracle Linux', cpu);
if ('x86_64' >!< cpu) audit(AUDIT_ARCH_NOT, 'x86_64', cpu);
var machine_uptrack_level = get_one_kb_item('Host/uptrack-uname-r');
if (machine_uptrack_level)
{
var trimmed_uptrack_level = ereg_replace(string:machine_uptrack_level, pattern:"\.(x86_64|i[3-6]86|aarch64)$", replace:'');
var fixed_uptrack_levels = ['4.1.12-124.48.3.1.el6uek', '4.1.12-124.48.3.1.el7uek'];
foreach var fixed_uptrack_level ( fixed_uptrack_levels ) {
if (rpm_spec_vers_cmp(a:trimmed_uptrack_level, b:fixed_uptrack_level) >= 0)
{
audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for ELSA-2021-9051');
}
}
__rpm_report = 'Running KSplice level of ' + trimmed_uptrack_level + ' does not meet the minimum fixed level of ' + join(fixed_uptrack_levels, sep:' / ') + ' for this advisory.\n\n';
}
var 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.');
var 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);
var pkgs = [
{'reference':'kernel-uek-4.1.12-124.48.3.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-4.1.12'},
{'reference':'kernel-uek-debug-4.1.12-124.48.3.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-debug-4.1.12'},
{'reference':'kernel-uek-debug-devel-4.1.12-124.48.3.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-debug-devel-4.1.12'},
{'reference':'kernel-uek-devel-4.1.12-124.48.3.1.el6uek', 'cpu':'x86_64', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-devel-4.1.12'},
{'reference':'kernel-uek-doc-4.1.12-124.48.3.1.el6uek', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-doc-4.1.12'},
{'reference':'kernel-uek-firmware-4.1.12-124.48.3.1.el6uek', 'release':'6', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-firmware-4.1.12'},
{'reference':'kernel-uek-4.1.12-124.48.3.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-4.1.12'},
{'reference':'kernel-uek-debug-4.1.12-124.48.3.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-debug-4.1.12'},
{'reference':'kernel-uek-debug-devel-4.1.12-124.48.3.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-debug-devel-4.1.12'},
{'reference':'kernel-uek-devel-4.1.12-124.48.3.1.el7uek', 'cpu':'x86_64', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-devel-4.1.12'},
{'reference':'kernel-uek-doc-4.1.12-124.48.3.1.el7uek', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-doc-4.1.12'},
{'reference':'kernel-uek-firmware-4.1.12-124.48.3.1.el7uek', 'release':'7', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-uek-firmware-4.1.12'}
];
var flag = 0;
foreach var package_array ( pkgs ) {
var reference = NULL;
var release = NULL;
var sp = NULL;
var cpu = NULL;
var el_string = NULL;
var rpm_spec_vers_cmp = NULL;
var epoch = NULL;
var allowmaj = NULL;
var exists_check = 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['exists_check'])) exists_check = package_array['exists_check'];
if (reference && release) {
if (exists_check) {
if (rpm_exists(release:release, rpm:exists_check) && 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_WARNING,
extra : rpm_report_get()
);
exit(0);
}
else
{
var 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');
}
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
14.2%