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nessusUbuntu Security Notice (C) 2018-2023 Canonical, Inc. / NASL script (C) 2018-2023 and is owned by Tenable, Inc. or an Affiliate thereof.UBUNTU_USN-3832-1.NASL
HistoryNov 30, 2018 - 12:00 a.m.

Ubuntu 18.10 : Linux kernel (AWS) vulnerabilities (USN-3832-1)

2018-11-3000:00:00
Ubuntu Security Notice (C) 2018-2023 Canonical, Inc. / NASL script (C) 2018-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
44

Jann Horn discovered that the procfs file system implementation in the Linux kernel did not properly restrict the ability to inspect the kernel stack of an arbitrary task. A local attacker could use this to expose sensitive information. (CVE-2018-17972)

Jann Horn discovered that the mremap() system call in the Linux kernel did not properly flush the TLB when completing, potentially leaving access to a physical page after it has been released to the page allocator. A local attacker could use this to cause a denial of service (system crash), expose sensitive information, or possibly execute arbitrary code. (CVE-2018-18281)

It was discovered that the BPF verifier in the Linux kernel did not correctly compute numeric bounds in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2018-18445)

Daniel Dadap discovered that the module loading implementation in the Linux kernel did not properly enforce signed module loading when booted with UEFI Secure Boot in some situations. A local privileged attacker could use this to execute untrusted code in the kernel.
(CVE-2018-18653)

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-3832-1. 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(119302);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/05/11");

  script_cve_id("CVE-2018-17972", "CVE-2018-18281", "CVE-2018-18445", "CVE-2018-18653", "CVE-2018-18955", "CVE-2018-6559");
  script_xref(name:"USN", value:"3832-1");

  script_name(english:"Ubuntu 18.10 : Linux kernel (AWS) vulnerabilities (USN-3832-1)");
  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 procfs file system implementation in the
Linux kernel did not properly restrict the ability to inspect the
kernel stack of an arbitrary task. A local attacker could use this to
expose sensitive information. (CVE-2018-17972)

Jann Horn discovered that the mremap() system call in the Linux kernel
did not properly flush the TLB when completing, potentially leaving
access to a physical page after it has been released to the page
allocator. A local attacker could use this to cause a denial of
service (system crash), expose sensitive information, or possibly
execute arbitrary code. (CVE-2018-18281)

It was discovered that the BPF verifier in the Linux kernel did not
correctly compute numeric bounds in some situations. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2018-18445)

Daniel Dadap discovered that the module loading implementation in the
Linux kernel did not properly enforce signed module loading when
booted with UEFI Secure Boot in some situations. A local privileged
attacker could use this to execute untrusted code in the kernel.
(CVE-2018-18653)

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/3832-1/"
  );
  script_set_attribute(
    attribute:"solution",
    value:
"Update the affected linux-image-4.18-aws and / or linux-image-aws
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:F/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/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-4.18-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-aws");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.10");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/10/03");
  script_set_attribute(attribute:"patch_publication_date", value:"2018/11/30");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/11/30");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2018-2023 Canonical, Inc. / NASL script (C) 2018-2023 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);
var release = get_kb_item("Host/Ubuntu/release");
if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu");
release = chomp(release);
if (! preg(pattern:"^(18\.10)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 18.10", "Ubuntu " + release);
if ( ! get_kb_item("Host/Debian/dpkg-l") ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) 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-2018-17972", "CVE-2018-18281", "CVE-2018-18445", "CVE-2018-18653", "CVE-2018-18955", "CVE-2018-6559");
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, "KSplice hotfix for USN-3832-1");
  }
  else
  {
    _ubuntu_report = ksplice_reporting_text();
  }
}

var flag = 0;

if (ubuntu_check(osver:"18.10", pkgname:"linux-image-4.18.0-1006-aws", pkgver:"4.18.0-1006.7")) flag++;
if (ubuntu_check(osver:"18.10", pkgname:"linux-image-aws", pkgver:"4.18.0.1006.6")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "linux-image-4.18-aws / linux-image-aws");
}