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
87.7%
The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2021-1811 advisory.
An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat size. (CVE-2020-14405)
An issue was discovered in LibVNCServer before 0.9.13. There is an information leak (of uninitialized memory contents) in the libvncclient/rfbproto.c ConnectToRFBRepeater function. (CVE-2018-21247)
libvncclient/sockets.c in LibVNCServer before 0.9.13 has a buffer overflow via a long socket filename.
(CVE-2019-20839)
An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rfbregion.c has a NULL pointer dereference. (CVE-2020-14397)
A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service. (CVE-2020-25708)
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-2021-1811.
##
include('deprecated_nasl_level.inc');
include('compat.inc');
if (description)
{
script_id(149968);
script_version("1.3");
script_set_attribute(attribute:"plugin_modification_date", value:"2023/12/28");
script_cve_id(
"CVE-2018-21247",
"CVE-2019-20839",
"CVE-2020-14397",
"CVE-2020-14405",
"CVE-2020-25708"
);
script_name(english:"Oracle Linux 8 : libvncserver (ELSA-2021-1811)");
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 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ELSA-2021-1811 advisory.
- An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat
size. (CVE-2020-14405)
- An issue was discovered in LibVNCServer before 0.9.13. There is an information leak (of uninitialized
memory contents) in the libvncclient/rfbproto.c ConnectToRFBRepeater function. (CVE-2018-21247)
- libvncclient/sockets.c in LibVNCServer before 0.9.13 has a buffer overflow via a long socket filename.
(CVE-2019-20839)
- An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rfbregion.c has a NULL pointer
dereference. (CVE-2020-14397)
- A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw
to send a specially crafted message that, when processed by the VNC server, would lead to a floating point
exception, resulting in a denial of service. (CVE-2020-25708)
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-2021-1811.html");
script_set_attribute(attribute:"solution", value:
"Update the affected libvncserver and / or libvncserver-devel packages.");
script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N");
script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N");
script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
script_set_attribute(attribute:"cvss_score_source", value:"CVE-2018-21247");
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:"2020/06/17");
script_set_attribute(attribute:"patch_publication_date", value:"2021/05/25");
script_set_attribute(attribute:"plugin_publication_date", value:"2021/05/26");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"cpe:/o:oracle:linux:8");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:libvncserver");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:oracle:linux:libvncserver-devel");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_family(english:"Oracle Linux Local Security Checks");
script_copyright(english:"This script is Copyright (C) 2021-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");
script_dependencies("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('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:"^8([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Oracle Linux 8', 'Oracle Linux ' + os_ver);
if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);
cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Oracle Linux', cpu);
pkgs = [
{'reference':'libvncserver-0.9.11-17.el8', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libvncserver-0.9.11-17.el8', 'cpu':'i686', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libvncserver-0.9.11-17.el8', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libvncserver-devel-0.9.11-17.el8', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libvncserver-devel-0.9.11-17.el8', 'cpu':'i686', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
{'reference':'libvncserver-devel-0.9.11-17.el8', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
];
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_WARNING,
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, 'libvncserver / libvncserver-devel');
}
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-21247
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-20839
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14397
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14405
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-25708
linux.oracle.com/errata/ELSA-2021-1811.html
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
87.7%