FreeBSD : krb5 -- RFC 3961 key-derivation checksum handling vulnerability (1d193bba-03f6-11e0-bf50-001a926c7637)

2010-12-10T00:00:00
ID FREEBSD_PKG_1D193BBA03F611E0BF50001A926C7637.NASL
Type nessus
Reporter Tenable
Modified 2018-07-12T00:00:00

Description

The MIT Kerberos team reports :

MIT krb5 (releases incorrectly accepts RFC 3961 key-derivation checksums using RC4 keys when verifying AD-SIGNEDPATH and AD-KDC-ISSUED authorization data.

An authenticated remote attacker that controls a legitimate service principal has a 1/256 chance of forging the AD-SIGNEDPATH signature if the TGT key is RC4, allowing it to use self-generated 'evidence' tickets for S4U2Proxy, instead of tickets obtained from the user or with S4U2Self. Configurations using RC4 for the TGT key are believed to be rare.

An authenticated remote attacker has a 1/256 chance of forging AD-KDC-ISSUED signatures on authdata elements in tickets having an RC4 service key, resulting in privilege escalation against a service that relies on these signatures. There are no known uses of the KDC-ISSUED authdata container at this time.

                                        
                                            #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from the FreeBSD VuXML database :
#
# Copyright 2003-2018 Jacques Vidrine and contributors
#
# Redistribution and use in source (VuXML) and 'compiled' forms (SGML,
# HTML, PDF, PostScript, RTF and so forth) with or without modification,
# are permitted provided that the following conditions are met:
# 1. Redistributions of source code (VuXML) must retain the above
#    copyright notice, this list of conditions and the following
#    disclaimer as the first lines of this file unmodified.
# 2. Redistributions in compiled form (transformed to other DTDs,
#    published online in any format, converted to PDF, PostScript,
#    RTF and other formats) must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer
#    in the documentation and/or other materials provided with the
#    distribution.
# 
# THIS DOCUMENTATION IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION,
# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

include("compat.inc");

if (description)
{
  script_id(51102);
  script_version("1.12");
  script_cvs_date("Date: 2018/07/12 15:01:52");

  script_cve_id("CVE-2010-4020");
  script_bugtraq_id(45117);

  script_name(english:"FreeBSD : krb5 -- RFC 3961 key-derivation checksum handling vulnerability (1d193bba-03f6-11e0-bf50-001a926c7637)");
  script_summary(english:"Checks for updated package in pkg_info output");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote FreeBSD host is missing a security-related update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"The MIT Kerberos team reports :

MIT krb5 (releases incorrectly accepts RFC 3961 key-derivation
checksums using RC4 keys when verifying AD-SIGNEDPATH and
AD-KDC-ISSUED authorization data.

An authenticated remote attacker that controls a legitimate service
principal has a 1/256 chance of forging the AD-SIGNEDPATH signature if
the TGT key is RC4, allowing it to use self-generated 'evidence'
tickets for S4U2Proxy, instead of tickets obtained from the user or
with S4U2Self. Configurations using RC4 for the TGT key are believed
to be rare.

An authenticated remote attacker has a 1/256 chance of forging
AD-KDC-ISSUED signatures on authdata elements in tickets having an RC4
service key, resulting in privilege escalation against a service that
relies on these signatures. There are no known uses of the KDC-ISSUED
authdata container at this time."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2010-007.txt"
  );
  # http://www.freebsd.org/ports/portaudit/1d193bba-03f6-11e0-bf50-001a926c7637.html
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?94865584"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected package.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:S/C:N/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:L/UI:N/S:U/C:L/I:L/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:krb5");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");

  script_set_attribute(attribute:"vuln_publication_date", value:"2010/11/30");
  script_set_attribute(attribute:"patch_publication_date", value:"2010/12/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2010/12/10");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2010-2018 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"FreeBSD Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info");

  exit(0);
}


include("audit.inc");
include("freebsd_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/FreeBSD/release")) audit(AUDIT_OS_NOT, "FreeBSD");
if (!get_kb_item("Host/FreeBSD/pkg_info")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;

if (pkg_test(save_report:TRUE, pkg:"krb5>=1.8.0<=1.8.3")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_note(port:0, extra:pkg_report_get());
  else security_note(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");