Ubuntu 18.04 LTS : linux, linux-gcp, linux-kvm, linux-raspi2 vulnerabilities (USN-3836-1)

2018-12-04T00:00:00
ID UBUNTU_USN-3836-1.NASL
Type nessus
Reporter Ubuntu Security Notice (C) 2018-2019 Canonical, Inc. / NASL script (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
Modified 2020-04-02T00:00:00

Description

Jann Horn discovered that the Linux kernel mishandles mapping UID or GID ranges inside nested user namespaces in some situations. A local attacker could use this to bypass access controls on resources outside the namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the Linux kernel did not properly verify the directory contents permissions from within a unprivileged user namespace. A local attacker could use this to expose sensitive information (protected file names). (CVE-2018-6559).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

                                        
                                            #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3836-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include("compat.inc");

if (description)
{
  script_id(119339);
  script_version("1.6");
  script_cvs_date("Date: 2019/09/18 12:31:49");

  script_cve_id("CVE-2018-18955", "CVE-2018-6559");
  script_xref(name:"USN", value:"3836-1");

  script_name(english:"Ubuntu 18.04 LTS : linux, linux-gcp, linux-kvm, linux-raspi2 vulnerabilities (USN-3836-1)");
  script_summary(english:"Checks dpkg output for updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Ubuntu host is missing one or more security-related
patches."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Jann Horn discovered that the Linux kernel mishandles mapping UID or
GID ranges inside nested user namespaces in some situations. A local
attacker could use this to bypass access controls on resources outside
the namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the
Linux kernel did not properly verify the directory contents
permissions from within a unprivileged user namespace. A local
attacker could use this to expose sensitive information (protected
file names). (CVE-2018-6559).

Note that Tenable Network Security has extracted the preceding
description block directly from the Ubuntu 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://usn.ubuntu.com/3836-1/"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:F/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:F/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Linux Nested User Namespace idmap Limit Local Privilege Escalation');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-lowlatency");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-raspi2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15-snapdragon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-gke");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-lowlatency");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-snapdragon");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/10/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2018/12/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/12/04");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2018-2019 Canonical, Inc. / NASL script (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Ubuntu Local Security Checks");

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

  exit(0);
}


include("audit.inc");
include("ubuntu.inc");
include("ksplice.inc");

if ( ! get_kb_item("Host/local_checks_enabled") ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/Ubuntu/release");
if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu");
release = chomp(release);
if (! preg(pattern:"^(18\.04)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 18.04", "Ubuntu " + release);
if ( ! get_kb_item("Host/Debian/dpkg-l") ) 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$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Ubuntu", cpu);

if (get_one_kb_item("Host/ksplice/kernel-cves"))
{
  rm_kb_item(name:"Host/uptrack-uname-r");
  cve_list = make_list("CVE-2018-18955", "CVE-2018-6559");
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, "KSplice hotfix for USN-3836-1");
  }
  else
  {
    _ubuntu_report = ksplice_reporting_text();
  }
}

flag = 0;

if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-1025-gcp", pkgver:"4.15.0-1025.26")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-1027-kvm", pkgver:"4.15.0-1027.27")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-1029-raspi2", pkgver:"4.15.0-1029.31")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-42-generic", pkgver:"4.15.0-42.45")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-42-generic-lpae", pkgver:"4.15.0-42.45")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-42-lowlatency", pkgver:"4.15.0-42.45")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-4.15.0-42-snapdragon", pkgver:"4.15.0-42.45")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-gcp", pkgver:"4.15.0.1025.27")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-generic", pkgver:"4.15.0.42.44")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-generic-lpae", pkgver:"4.15.0.42.44")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-gke", pkgver:"4.15.0.1025.27")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-kvm", pkgver:"4.15.0.1027.27")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-lowlatency", pkgver:"4.15.0.42.44")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-raspi2", pkgver:"4.15.0.1029.27")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"linux-image-snapdragon", pkgver:"4.15.0.42.44")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "linux-image-4.15-gcp / linux-image-4.15-generic / etc");
}