CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
78.1%
The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2021:1593 advisory.
Kerberos is a network authentication system, which can improve the security of your network by eliminating the insecure practice of sending passwords over the network in unencrypted form. It allows clients and servers to authenticate to each other with the help of a trusted third party, the Kerberos key distribution center (KDC).
Security Fix(es):
* krb5: unbounded recursion via an ASN.1-encoded Kerberos message in lib/krb5/asn.1/asn1_encode.c may lead to DoS (CVE-2020-28196)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Additional Changes:
For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes linked from the References section.
Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.
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, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2021:1593. The text
# itself is copyright (C) Red Hat, Inc.
##
include('deprecated_nasl_level.inc');
include('compat.inc');
if (description)
{
script_id(149693);
script_version("1.11");
script_set_attribute(attribute:"plugin_modification_date", value:"2024/06/03");
script_cve_id("CVE-2020-28196");
script_xref(name:"RHSA", value:"2021:1593");
script_xref(name:"CEA-ID", value:"CEA-2021-0025");
script_name(english:"RHEL 8 : krb5 (RHSA-2021:1593)");
script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing a security update for krb5.");
script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in
the RHSA-2021:1593 advisory.
Kerberos is a network authentication system, which can improve the security of your network by eliminating
the insecure practice of sending passwords over the network in unencrypted form. It allows clients and
servers to authenticate to each other with the help of a trusted third party, the Kerberos key
distribution center (KDC).
Security Fix(es):
* krb5: unbounded recursion via an ASN.1-encoded Kerberos message in lib/krb5/asn.1/asn1_encode.c may lead
to DoS (CVE-2020-28196)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and
other related information, refer to the CVE page(s) listed in the References section.
Additional Changes:
For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes
linked from the References section.
Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
# https://access.redhat.com/security/data/csaf/v2/advisories/2021/rhsa-2021_1593.json
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7013fe46");
# https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/
script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?862005a9");
script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/updates/classification/#moderate");
script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2021:1593");
script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1835713");
script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1868039");
script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1869055");
script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1872689");
script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1901041");
script_set_attribute(attribute:"solution", value:
"Update the RHEL krb5 package based on the guidance in RHSA-2021:1593.");
script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
script_set_cvss_temporal_vector("CVSS2#E:F/RL:OF/RC:C");
script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
script_set_cvss3_temporal_vector("CVSS:3.0/E:F/RL:O/RC:C");
script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-28196");
script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
script_set_attribute(attribute:"exploit_available", value:"true");
script_cwe_id(674);
script_set_attribute(attribute:"vendor_severity", value:"Moderate");
script_set_attribute(attribute:"vuln_publication_date", value:"2020/11/05");
script_set_attribute(attribute:"patch_publication_date", value:"2021/05/18");
script_set_attribute(attribute:"plugin_publication_date", value:"2021/05/19");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-devel");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-libs");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-pkinit");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-server");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-server-ldap");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:krb5-workstation");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:libkadm5");
script_set_attribute(attribute:"generated_plugin", value:"current");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_family(english:"Red Hat Local Security Checks");
script_copyright(english:"This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");
script_dependencies("ssh_get_info.nasl", "redhat_repos.nasl");
script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/cpu");
exit(0);
}
include('rpm.inc');
include('rhel.inc');
if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/RedHat/release');
if (isnull(os_release) || 'Red Hat' >!< os_release) audit(AUDIT_OS_NOT, 'Red Hat');
var os_ver = pregmatch(pattern: "Red Hat Enterprise Linux.*release ([0-9]+(\.[0-9]+)?)", string:os_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
os_ver = os_ver[1];
if (!rhel_check_release(operator: 'ge', os_version: os_ver, rhel_version: '8')) audit(AUDIT_OS_NOT, 'Red Hat 8.x', 'Red Hat ' + 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$" && 's390' >!< cpu && 'aarch64' >!< cpu && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);
var constraints = [
{
'repo_relative_urls': [
'content/dist/rhel8/8.10/aarch64/baseos/debug',
'content/dist/rhel8/8.10/aarch64/baseos/os',
'content/dist/rhel8/8.10/aarch64/baseos/source/SRPMS',
'content/dist/rhel8/8.10/ppc64le/baseos/debug',
'content/dist/rhel8/8.10/ppc64le/baseos/os',
'content/dist/rhel8/8.10/ppc64le/baseos/source/SRPMS',
'content/dist/rhel8/8.10/s390x/baseos/debug',
'content/dist/rhel8/8.10/s390x/baseos/os',
'content/dist/rhel8/8.10/s390x/baseos/source/SRPMS',
'content/dist/rhel8/8.10/x86_64/baseos/debug',
'content/dist/rhel8/8.10/x86_64/baseos/os',
'content/dist/rhel8/8.10/x86_64/baseos/source/SRPMS',
'content/dist/rhel8/8.6/aarch64/baseos/debug',
'content/dist/rhel8/8.6/aarch64/baseos/os',
'content/dist/rhel8/8.6/aarch64/baseos/source/SRPMS',
'content/dist/rhel8/8.6/ppc64le/baseos/debug',
'content/dist/rhel8/8.6/ppc64le/baseos/os',
'content/dist/rhel8/8.6/ppc64le/baseos/source/SRPMS',
'content/dist/rhel8/8.6/s390x/baseos/debug',
'content/dist/rhel8/8.6/s390x/baseos/os',
'content/dist/rhel8/8.6/s390x/baseos/source/SRPMS',
'content/dist/rhel8/8.6/x86_64/baseos/debug',
'content/dist/rhel8/8.6/x86_64/baseos/os',
'content/dist/rhel8/8.6/x86_64/baseos/source/SRPMS',
'content/dist/rhel8/8.8/aarch64/baseos/debug',
'content/dist/rhel8/8.8/aarch64/baseos/os',
'content/dist/rhel8/8.8/aarch64/baseos/source/SRPMS',
'content/dist/rhel8/8.8/ppc64le/baseos/debug',
'content/dist/rhel8/8.8/ppc64le/baseos/os',
'content/dist/rhel8/8.8/ppc64le/baseos/source/SRPMS',
'content/dist/rhel8/8.8/s390x/baseos/debug',
'content/dist/rhel8/8.8/s390x/baseos/os',
'content/dist/rhel8/8.8/s390x/baseos/source/SRPMS',
'content/dist/rhel8/8.8/x86_64/baseos/debug',
'content/dist/rhel8/8.8/x86_64/baseos/os',
'content/dist/rhel8/8.8/x86_64/baseos/source/SRPMS',
'content/dist/rhel8/8.9/aarch64/baseos/debug',
'content/dist/rhel8/8.9/aarch64/baseos/os',
'content/dist/rhel8/8.9/aarch64/baseos/source/SRPMS',
'content/dist/rhel8/8.9/ppc64le/baseos/debug',
'content/dist/rhel8/8.9/ppc64le/baseos/os',
'content/dist/rhel8/8.9/ppc64le/baseos/source/SRPMS',
'content/dist/rhel8/8.9/s390x/baseos/debug',
'content/dist/rhel8/8.9/s390x/baseos/os',
'content/dist/rhel8/8.9/s390x/baseos/source/SRPMS',
'content/dist/rhel8/8.9/x86_64/baseos/debug',
'content/dist/rhel8/8.9/x86_64/baseos/os',
'content/dist/rhel8/8.9/x86_64/baseos/source/SRPMS',
'content/dist/rhel8/8/aarch64/baseos/debug',
'content/dist/rhel8/8/aarch64/baseos/os',
'content/dist/rhel8/8/aarch64/baseos/source/SRPMS',
'content/dist/rhel8/8/ppc64le/baseos/debug',
'content/dist/rhel8/8/ppc64le/baseos/os',
'content/dist/rhel8/8/ppc64le/baseos/source/SRPMS',
'content/dist/rhel8/8/s390x/baseos/debug',
'content/dist/rhel8/8/s390x/baseos/os',
'content/dist/rhel8/8/s390x/baseos/source/SRPMS',
'content/dist/rhel8/8/x86_64/baseos/debug',
'content/dist/rhel8/8/x86_64/baseos/os',
'content/dist/rhel8/8/x86_64/baseos/source/SRPMS'
],
'pkgs': [
{'reference':'krb5-devel-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'krb5-libs-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'krb5-pkinit-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'krb5-server-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'krb5-server-ldap-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'krb5-workstation-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libkadm5-1.18.2-8.el8', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
]
}
];
var applicable_repo_urls = rhel_determine_applicable_repository_urls(constraints:constraints);
if(applicable_repo_urls == RHEL_REPOS_NO_OVERLAP_MESSAGE) exit(0, RHEL_REPO_NOT_ENABLED);
var flag = 0;
foreach var constraint_array ( constraints ) {
var repo_relative_urls = NULL;
if (!empty_or_null(constraint_array['repo_relative_urls'])) repo_relative_urls = constraint_array['repo_relative_urls'];
foreach var pkg ( constraint_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;
var cves = NULL;
if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
if (!empty_or_null(pkg['release'])) _release = 'RHEL' + pkg['release'];
if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
if (reference &&
_release &&
rhel_decide_repo_relative_url_check(required_repo_url_list:repo_relative_urls) &&
(applicable_repo_urls || (!exists_check || 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, cves:cves)) flag++;
}
}
if (flag)
{
var extra = NULL;
if (isnull(applicable_repo_urls) || !applicable_repo_urls) extra = rpm_report_get() + redhat_report_repo_caveat();
else extra = rpm_report_get();
security_report_v4(
port : 0,
severity : SECURITY_WARNING,
extra : extra
);
exit(0);
}
else
{
var tested = pkg_tests_get();
if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'krb5-devel / krb5-libs / krb5-pkinit / krb5-server / etc');
}
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-28196
www.nessus.org/u?7013fe46
www.nessus.org/u?862005a9
access.redhat.com/errata/RHSA-2021:1593
access.redhat.com/security/updates/classification/#moderate
bugzilla.redhat.com/show_bug.cgi?id=1835713
bugzilla.redhat.com/show_bug.cgi?id=1868039
bugzilla.redhat.com/show_bug.cgi?id=1869055
bugzilla.redhat.com/show_bug.cgi?id=1872689
bugzilla.redhat.com/show_bug.cgi?id=1901041
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
78.1%