Amazon Linux AMI : openssh (ALAS-2016-668)

2016-03-17T00:00:00
ID ALA_ALAS-2016-668.NASL
Type nessus
Reporter This script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
Modified 2020-09-02T00:00:00

Description

It was discovered that the OpenSSH server did not sanitize data received in requests to enable X11 forwarding. An authenticated client with restricted SSH access could possibly use this flaw to bypass intended restrictions.

                                        
                                            #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2016-668.
#

include("compat.inc");

if (description)
{
  script_id(89965);
  script_version("2.5");
  script_cvs_date("Date: 2019/04/11 17:23:06");

  script_cve_id("CVE-2016-3115");
  script_xref(name:"ALAS", value:"2016-668");

  script_name(english:"Amazon Linux AMI : openssh (ALAS-2016-668)");
  script_summary(english:"Checks rpm output for the updated packages");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Amazon Linux AMI host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"It was discovered that the OpenSSH server did not sanitize data
received in requests to enable X11 forwarding. An authenticated client
with restricted SSH access could possibly use this flaw to bypass
intended restrictions."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://alas.aws.amazon.com/ALAS-2016-668.html"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Run 'yum update openssh' to update your system."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/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:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-clients");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-keycat");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-ldap");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:pam_ssh_agent_auth");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");

  script_set_attribute(attribute:"patch_publication_date", value:"2016/03/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/03/17");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2019 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 != "A")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux AMI", "Amazon Linux " + os_ver);
}

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


flag = 0;
if (rpm_check(release:"ALA", reference:"openssh-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssh-clients-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssh-debuginfo-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssh-keycat-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssh-ldap-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssh-server-6.6.1p1-23.60.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"pam_ssh_agent_auth-0.9.3-9.23.60.amzn1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
  else security_warning(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "openssh / openssh-clients / openssh-debuginfo / openssh-keycat / etc");
}