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CentOS 7 : kernel (CESA-2019:1481) (SACK Panic) (SACK Slowness)

2019-06-19T00:00:00
ID CENTOS_RHSA-2019-1481.NASL
Type nessus
Reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
Modified 2021-03-02T00:00:00

Description

An update for kernel is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es) :

  • An integer overflow flaw was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented. Each fragment is about TCP maximum segment size (MSS) bytes. To efficiently process SACK blocks, the Linux kernel merges multiple fragmented SKBs into one, potentially overflowing the variable holding the number of segments. A remote attacker could use this flaw to crash the Linux kernel by sending a crafted sequence of SACK segments on a TCP connection with small value of TCP MSS, resulting in a denial of service (DoS). (CVE-2019-11477)

  • Kernel: tcp: excessive resource consumption while processing SACK blocks allows remote denial of service (CVE-2019-11478)

  • Kernel: tcp: excessive resource consumption for TCP connections with low MSS allows remote denial of service (CVE-2019-11479)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

                                        
                                            #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Red Hat Security Advisory RHSA-2019:1481 and 
# CentOS Errata and Security Advisory 2019:1481 respectively.
#

include("compat.inc");

if (description)
{
  script_id(126006);
  script_version("1.6");
  script_cvs_date("Date: 2020/01/10");

  script_cve_id("CVE-2019-11477", "CVE-2019-11478", "CVE-2019-11479");
  script_xref(name:"RHSA", value:"2019:1481");

  script_name(english:"CentOS 7 : kernel (CESA-2019:1481) (SACK Panic) (SACK Slowness)");
  script_summary(english:"Checks rpm output for the updated packages");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote CentOS host is missing one or more security updates."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"An update for kernel is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security
impact of Important. A Common Vulnerability Scoring System (CVSS) base
score, which gives a detailed severity rating, is available for each
vulnerability from the CVE link(s) in the References section.

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

Security Fix(es) :

* An integer overflow flaw was found in the way the Linux kernel's
networking subsystem processed TCP Selective Acknowledgment (SACK)
segments. While processing SACK segments, the Linux kernel's socket
buffer (SKB) data structure becomes fragmented. Each fragment is about
TCP maximum segment size (MSS) bytes. To efficiently process SACK
blocks, the Linux kernel merges multiple fragmented SKBs into one,
potentially overflowing the variable holding the number of segments. A
remote attacker could use this flaw to crash the Linux kernel by
sending a crafted sequence of SACK segments on a TCP connection with
small value of TCP MSS, resulting in a denial of service (DoS).
(CVE-2019-11477)

* Kernel: tcp: excessive resource consumption while processing SACK
blocks allows remote denial of service (CVE-2019-11478)

* Kernel: tcp: excessive resource consumption for TCP connections with
low MSS allows remote denial of service (CVE-2019-11479)

For more details about the security issue(s), including the impact, a
CVSS score, acknowledgments, and other related information, refer to
the CVE page(s) listed in the References section."
  );
  # https://lists.centos.org/pipermail/centos-announce/2019-June/023333.html
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?913cb631"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected kernel packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-11477");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:bpftool");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-abi-whitelists");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-debug");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-debug-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-headers");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-tools-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:kernel-tools-libs-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:perf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:python-perf");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:7");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/06/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/06/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/06/19");
  script_set_attribute(attribute:"in_the_news", value:"true");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"CentOS Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/CentOS/release", "Host/CentOS/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/CentOS/release");
if (isnull(release) || "CentOS" >!< release) audit(AUDIT_OS_NOT, "CentOS");
os_ver = pregmatch(pattern: "CentOS(?: Linux)? release ([0-9]+)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "CentOS");
os_ver = os_ver[1];
if (! preg(pattern:"^7([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "CentOS 7.x", "CentOS " + os_ver);

if (!get_kb_item("Host/CentOS/rpm-list")) 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, "CentOS", cpu);


flag = 0;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"bpftool-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-abi-whitelists-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-debug-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-debug-devel-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-devel-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-doc-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-headers-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-tools-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-tools-libs-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"kernel-tools-libs-devel-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"perf-3.10.0-957.21.3.el7")) flag++;
if (rpm_check(release:"CentOS-7", cpu:"x86_64", reference:"python-perf-3.10.0-957.21.3.el7")) flag++;


if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "bpftool / kernel / kernel-abi-whitelists / kernel-debug / etc");
}
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