Amazon Linux 2 : kernel (ALAS-2018-994)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2018-994.
#

include("compat.inc");

if (description)
{
  script_id(109177);
  script_version("1.3");
  script_cvs_date("Date: 2018/09/19 10:04:09");

  script_cve_id("CVE-2017-13215", "CVE-2018-10675", "CVE-2018-1068", "CVE-2018-10901", "CVE-2018-7995");
  script_xref(name:"ALAS", value:"2018-994");

  script_name(english:"Amazon Linux 2 : kernel (ALAS-2018-994)");
  script_summary(english:"Checks rpm output for the updated packages");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Amazon Linux 2 host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Race condition in the store_int_with_restart() function in
cpu/mcheck/mce.c :

A race condition in the store_int_with_restart() function in
arch/x86/kernel/cpu/mcheck/mce.c in the Linux kernel allows local
users to cause a denial of service (panic) by leveraging root access
to write to the check_interval file in a
/sys/devices/system/machinecheck/machinecheck<cpu number> directory.
(CVE-2018-7995)

Out-of-bounds write via userland offsets in ebt_entry struct in
netfilter/ebtables.c :

A flaw was found in the Linux kernel's implementation of 32-bit
syscall interface for bridging. This allowed a privileged user to
arbitrarily write to a limited range of kernel memory. (CVE-2018-1068)

A flaw was found in the Linux kernel's skcipher component, which
affects the skcipher_recvmsg function. Attackers using a specific
input can lead to a privilege escalation.(CVE-2017-13215)

The do_get_mempolicy() function in mm/mempolicy.c in the Linux kernel
allows local users to hit a use-after-free bug via crafted system
calls and thus cause a denial of service (DoS) or possibly have
unspecified other impact. Due to the nature of the flaw, privilege
escalation cannot be fully ruled out.(CVE-2018-10675)

A flaw was found in Linux kernel's KVM virtualization subsystem. The
VMX code does not restore the GDT.LIMIT to the previous host value,
but instead sets it to 64KB. With a corrupted GDT limit a host's
userspace code has an ability to place malicious entries in the GDT,
particularly to the per-cpu variables. An attacker can use this to
escalate their privileges.(CVE-2018-10901)"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://alas.aws.amazon.com/AL2/ALAS-2018-994.html"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"Run 'yum update kernel' to update the kernel and reboot your instance
to start the new kernel"
  );
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A: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_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-headers");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perf-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-perf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-perf-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");

  script_set_attribute(attribute:"patch_publication_date", value:"2018/09/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/04/20");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Amazon Linux Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("rpm.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

release = get_kb_item("Host/AmazonLinux/release");
if (isnull(release) || !strlen(release)) audit(AUDIT_OS_NOT, "Amazon Linux");
os_ver = pregmatch(pattern: "^AL(A|\d)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-debuginfo-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-debuginfo-common-x86_64-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-devel-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-headers-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-tools-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-tools-debuginfo-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"kernel-tools-devel-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"perf-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"perf-debuginfo-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"python-perf-4.14.33-59.34.amzn2")) flag++;
if (rpm_check(release:"AL2", cpu:"x86_64", reference:"python-perf-debuginfo-4.14.33-59.34.amzn2")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get());
  else security_hole(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "kernel / kernel-debuginfo / kernel-debuginfo-common-x86_64 / etc");
}