Debian DLA-720-1 : xen security update

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory DLA-720-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(95296);
  script_version("3.12");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/01/11");

  script_cve_id("CVE-2016-9379", "CVE-2016-9380", "CVE-2016-9381", "CVE-2016-9382", "CVE-2016-9383", "CVE-2016-9386");
  script_xref(name:"IAVB", value:"2016-B-0177-S");

  script_name(english:"Debian DLA-720-1 : xen security update");
  script_summary(english:"Checks dpkg output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Multiple vulnerabilities have been discovered in the Xen hypervisor.
The Common Vulnerabilities and Exposures project identifies the
following problems :

CVE-2016-9379, CVE-2016-9380 (XSA-198)

pygrub, the boot loader emulator, fails to quote (or sanity check) its
results when reporting them to its caller. A malicious guest
administrator can obtain the contents of sensitive host files

CVE-2016-9381 (XSA-197)

The compiler can emit optimizations in qemu which can lead to double
fetch vulnerabilities. Malicious administrators can exploit this
vulnerability to take over the qemu process, elevating its privilege
to that of the qemu process. 

CVE-2016-9382 (XSA-192)

LDTR, just like TR, is purely a protected mode facility. Hence even
when switching to a VM86 mode task, LDTR loading needs to follow
protected mode semantics. A malicious unprivileged guest process can
crash or escalate its privilege to that of the guest operating system.

CVE-2016-9383 (XSA-195)

When Xen needs to emulate some instruction, to efficiently handle the
emulation, the memory address and register operand are recalculated
internally to Xen. In this process, the high bits of an intermediate
expression were discarded, leading to both the memory location and the
register operand being wrong. A malicious guest can modify arbitrary
memory.

CVE-2016-9386 (XSA-191)

The Xen x86 emulator erroneously failed to consider the unusability of
segments when performing memory accesses. An unprivileged guest user
program may be able to elevate its privilege to that of the guest
operating system.

For Debian 7 'Wheezy', these problems have been fixed in version
4.1.6.lts1-4. For Debian 8 'Jessie', these problems will be fixed
shortly.

We recommend that you upgrade your xen packages.

NOTE: Tenable Network Security has extracted the preceding description
block directly from the DLA security advisory. Tenable has attempted
to automatically clean and format it as much as possible without
introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://lists.debian.org/debian-lts-announce/2016/11/msg00026.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/wheezy/xen"
  );
  script_set_attribute(attribute:"solution", value:"Upgrade the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H");
  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:debian:debian_linux:libxen-4.1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxen-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxen-ocaml");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxen-ocaml-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libxenstore3.0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-docs-4.1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-hypervisor-4.1-amd64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-hypervisor-4.1-i386");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-system-amd64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-system-i386");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-utils-4.1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xen-utils-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:xenstore-utils");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:7.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2016/11/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/11/25");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2021 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Debian Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");

  exit(0);
}


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


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (deb_check(release:"7.0", prefix:"libxen-4.1", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"libxen-dev", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"libxen-ocaml", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"libxen-ocaml-dev", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"libxenstore3.0", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-docs-4.1", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-hypervisor-4.1-amd64", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-hypervisor-4.1-i386", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-system-amd64", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-system-i386", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-utils-4.1", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xen-utils-common", reference:"4.1.6.lts1-4")) flag++;
if (deb_check(release:"7.0", prefix:"xenstore-utils", reference:"4.1.6.lts1-4")) flag++;

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