Vulnerabilities > CVE-2020-13645 - Improper Certificate Validation vulnerability in multiple products

047910
CVSS 6.5 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
LOW
Integrity impact
LOW
Availability impact
NONE
network
low complexity
gnome
canonical
fedoraproject
netapp
broadcom
CWE-295
nessus
NVD
Published: 2020-05-28
Updated: 2023-11-07

Summary

In GNOME glib-networking through 2.64.2, the implementation of GTlsClientConnection skips hostname verification of the server's TLS certificate if the application fails to specify the expected server identity. This is in contrast to its intended documented behavior, to fail the certificate verification. Applications that fail to provide the server identity, including Balsa before 2.5.11 and 2.6.x before 2.6.1, accept a TLS certificate if the certificate is valid for any host.

Vulnerable Configurations

Part Description Count
Application
Gnome
119
Application
Netapp
1
OS
Canonical
4
OS
Fedoraproject
2
OS
Broadcom
1

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Creating a Rogue Certificate Authority Certificate
    An attacker exploits a weakness in the MD5 hash algorithm (weak collision resistance) to generate a certificate signing request (CSR) that contains collision blocks in the "to be signed" part. The attacker specially crafts two different, but valid X.509 certificates that when hashed with the MD5 algorithm would yield the same value. The attacker then sends the CSR for one of the certificates to the Certification Authority which uses the MD5 hashing algorithm. That request is completely valid and the Certificate Authority issues an X.509 certificate to the attacker which is signed with its private key. An attacker then takes that signed blob and inserts it into another X.509 certificate that the attacker generated. Due to the MD5 collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the attackers' second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority. To make the attack more interesting, the second certificate could be not just a regular certificate, but rather itself a signing certificate. Thus the attacker is able to start their own Certification Authority that is anchored in its root of trust in the legitimate Certification Authority that has signed the attackers' first X.509 certificate. If the original Certificate Authority was accepted by default by browsers, so will now the Certificate Authority set up by the attacker and of course any certificates that it signs. So the attacker is now able to generate any SSL certificates to impersonate any web server, and the user's browser will not issue any warning to the victim. This can be used to compromise HTTPS communications and other types of systems where PKI and X.509 certificates may be used (e.g., VPN, IPSec) .

Nessus

NASL familyPhotonOS Local Security Checks
NASL idPHOTONOS_PHSA-2020-2_0-0252_GLIB.NASL
descriptionAn update of the glib package has been released.
last seen2020-06-12
modified2020-06-10
plugin id137302
published2020-06-10
reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/137302
titlePhoton OS 2.0: Glib PHSA-2020-2.0-0252
code
#
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were
# extracted from VMware Security Advisory PHSA-2020-2.0-0252. The text
# itself is copyright (C) VMware, Inc.

include('compat.inc');

if (description)
{
  script_id(137302);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/11");

  script_cve_id("CVE-2020-13645");

  script_name(english:"Photon OS 2.0: Glib PHSA-2020-2.0-0252");

  script_set_attribute(attribute:"synopsis", value:
"The remote PhotonOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"An update of the glib package has been released.");
  script_set_attribute(attribute:"see_also", value:"https://github.com/vmware/photon/wiki/Security-Updates-2-252.md");
  script_set_attribute(attribute:"solution", value:
"Update the affected Linux packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-13645");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/05/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/06/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/10");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:vmware:photonos:glib");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:vmware:photonos:2.0");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  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);

release = get_kb_item("Host/PhotonOS/release");
if (isnull(release) || release !~ "^VMware Photon") audit(AUDIT_OS_NOT, "PhotonOS");
if (release !~ "^VMware Photon (?:Linux|OS) 2\.0(\D|$)") audit(AUDIT_OS_NOT, "PhotonOS 2.0");

if (!get_kb_item("Host/PhotonOS/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, "PhotonOS", cpu);

flag = 0;

if (rpm_check(release:"PhotonOS-2.0", cpu:"x86_64", reference:"glib-networking-2.50.0-2.ph2")) flag++;
if (rpm_check(release:"PhotonOS-2.0", cpu:"x86_64", reference:"glib-networking-lang-2.50.0-2.ph2")) 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, "glib");
}

References