Vulnerabilities > CVE-2014-8475 - Code vulnerability in Freebsd 10.0/9.1/9.2

047910
CVSS 4.3 - MEDIUM
Attack vector
NETWORK
Attack complexity
MEDIUM
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
PARTIAL
network
freebsd
CWE-17
nessus

Summary

FreeBSD 9.1, 9.2, and 10.0, when compiling OpenSSH with Kerberos support, uses incorrect library ordering when linking sshd, which causes symbols to be resolved incorrectly and allows remote attackers to cause a denial of service (sshd deadlock and prevention of new connections) by ending multiple connections before authentication is completed.

Vulnerable Configurations

Part Description Count
OS
Freebsd
3

Common Weakness Enumeration (CWE)

Nessus

NASL familyFreeBSD Local Security Checks
NASL idFREEBSD_PKG_73E9A137600711E6A6C314DAE9D210B8.NASL
descriptionAlthough OpenSSH is not multithreaded, when OpenSSH is compiled with Kerberos support, the Heimdal libraries bring in the POSIX thread library as a dependency. Due to incorrect library ordering while linking sshd(8), symbols in the C library which are shadowed by the POSIX thread library may not be resolved correctly at run time. Note that this problem is specific to the FreeBSD build system and does not affect other operating systems or the version of OpenSSH available from the FreeBSD ports tree. Impact : An incorrectly linked sshd(8) child process may deadlock while handling an incoming connection. The connection may then time out or be interrupted by the client, leaving the deadlocked sshd(8) child process behind. Eventually, the sshd(8) parent process stops accepting new connections. An attacker may take advantage of this by repeatedly connecting and then dropping the connection after having begun, but not completed, the authentication process.
last seen2020-06-01
modified2020-06-02
plugin id92911
published2016-08-12
reporterThis script is Copyright (C) 2016-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/92911
titleFreeBSD : FreeBSD -- Denial of service attack against sshd(8) (73e9a137-6007-11e6-a6c3-14dae9d210b8)
code
#
# (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(92911);
  script_version("2.3");
  script_cvs_date("Date: 2018/12/05 20:31:22");

  script_cve_id("CVE-2014-8475");
  script_bugtraq_id(70913);
  script_xref(name:"FreeBSD", value:"SA-14:24.sshd");

  script_name(english:"FreeBSD : FreeBSD -- Denial of service attack against sshd(8) (73e9a137-6007-11e6-a6c3-14dae9d210b8)");
  script_summary(english:"Checks for updated packages in pkg_info output");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote FreeBSD host is missing one or more security-related
updates."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Although OpenSSH is not multithreaded, when OpenSSH is compiled with
Kerberos support, the Heimdal libraries bring in the POSIX thread
library as a dependency. Due to incorrect library ordering while
linking sshd(8), symbols in the C library which are shadowed by the
POSIX thread library may not be resolved correctly at run time.

Note that this problem is specific to the FreeBSD build system and
does not affect other operating systems or the version of OpenSSH
available from the FreeBSD ports tree. Impact : An incorrectly linked
sshd(8) child process may deadlock while handling an incoming
connection. The connection may then time out or be interrupted by the
client, leaving the deadlocked sshd(8) child process behind.
Eventually, the sshd(8) parent process stops accepting new
connections.

An attacker may take advantage of this by repeatedly connecting and
then dropping the connection after having begun, but not completed,
the authentication process."
  );
  # https://vuxml.freebsd.org/freebsd/73e9a137-6007-11e6-a6c3-14dae9d210b8.html
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?167a6491"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/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:FreeBSD");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");

  script_set_attribute(attribute:"vuln_publication_date", value:"2014/11/04");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/08/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/08/12");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2018 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", "Settings/ParanoidReport");

  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);


if (report_paranoia < 2) audit(AUDIT_PARANOID);

flag = 0;

if (pkg_test(save_report:TRUE, pkg:"FreeBSD>=10.0<10.0_12")) flag++;
if (pkg_test(save_report:TRUE, pkg:"FreeBSD>=9.2<9.2_15")) flag++;
if (pkg_test(save_report:TRUE, pkg:"FreeBSD>=9.1<9.1_22")) flag++;

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