FreeBSD : xen-kernel -- ioreq handling possibly susceptible to multiple read issue (6aa2d135-b40e-11e5-9728-002590263bf5)

2016-01-06T00:00:00
ID FREEBSD_PKG_6AA2D135B40E11E59728002590263BF5.NASL
Type nessus
Reporter This script is Copyright (C) 2016-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
Modified 2020-03-02T00:00:00

Description

The Xen Project reports :

Single memory accesses in source code can be translated to multiple ones in machine code by the compiler, requiring special caution when accessing shared memory. Such precaution was missing from the hypervisor code inspecting the state of I/O requests sent to the device model for assistance.

Due to the offending field being a bitfield, it is however believed that there is no issue in practice, since compilers, at least when optimizing (which is always the case for non-debug builds), should find it more expensive to extract the bit field value twice than to keep the calculated value in a register.

This vulnerability is exposed to malicious device models. In conventional Xen systems this means the qemu which service an HVM domain. On such systems this vulnerability can only be exploited if the attacker has gained control of the device model qemu via another vulnerability.

Privilege escalation, host crash (Denial of Service), and leaked information all cannot be excluded.

                                        
                                            #
# (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(87746);
  script_version("2.2");
  script_cvs_date("Date: 2018/11/10 11:49:45");

  script_name(english:"FreeBSD : xen-kernel -- ioreq handling possibly susceptible to multiple read issue (6aa2d135-b40e-11e5-9728-002590263bf5)");
  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 Xen Project reports :

Single memory accesses in source code can be translated to multiple
ones in machine code by the compiler, requiring special caution when
accessing shared memory. Such precaution was missing from the
hypervisor code inspecting the state of I/O requests sent to the
device model for assistance.

Due to the offending field being a bitfield, it is however believed
that there is no issue in practice, since compilers, at least when
optimizing (which is always the case for non-debug builds), should
find it more expensive to extract the bit field value twice than to
keep the calculated value in a register.

This vulnerability is exposed to malicious device models. In
conventional Xen systems this means the qemu which service an HVM
domain. On such systems this vulnerability can only be exploited if
the attacker has gained control of the device model qemu via another
vulnerability.

Privilege escalation, host crash (Denial of Service), and leaked
information all cannot be excluded."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=205841"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"http://xenbits.xen.org/xsa/advisory-166.html"
  );
  # https://vuxml.freebsd.org/freebsd/6aa2d135-b40e-11e5-9728-002590263bf5.html
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?796052b3"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected package.");
  script_set_attribute(attribute:"risk_factor", value:"High");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2015/12/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/01/06");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/01/06");
  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");

  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:"xen-kernel<4.5.2_1")) flag++;

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