Amazon Linux Local Check: ALAS-2015-520

2015-09-08T00:00:00
ID OPENVAS:1361412562310120060
Type openvas
Reporter Eero Volotinen
Modified 2017-07-06T00:00:00

Description

Amazon Linux Local Security Checks

                                        
                                            # OpenVAS Vulnerability Test 
# Description: Amazon Linux security check 
# $Id: alas-2015-520.nasl 6575 2017-07-06 13:42:08Z cfischer $
 
# Authors: 
# Eero Volotinen <eero.volotinen@iki.fi> 
#
# Copyright:
# Copyright (c) 2015 Eero Volotinen, http://ping-viini.org 
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2
# (or any later version), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
#
if(description)
 {
script_oid("1.3.6.1.4.1.25623.1.0.120060");
script_version("$Revision: 6575 $");
script_tag(name:"creation_date", value:"2015-09-08 13:16:30 +0200 (Tue, 08 Sep 2015)");
script_tag(name:"last_modification", value:"$Date: 2017-07-06 15:42:08 +0200 (Thu, 06 Jul 2017) $");
script_name("Amazon Linux Local Check: ALAS-2015-520");
script_tag(name: "insight", value: "The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 4.x before 4.2.8p2 requires a correct MAC only if the MAC field has a nonzero length, which makes it easier for man-in-the-middle attackers to spoof packets by omitting the MAC. (CVE-2015-1798 )The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 3.x and 4.x before 4.2.8p2 performs state-variable updates upon receiving certain invalid packets, which makes it easier for man-in-the-middle attackers to cause a denial of service (synchronization loss) by spoofing the source IP address of a peer. (CVE-2015-1799 )This update also addresses leap-second handling.  With older ntp versions, the -x option was sometimes used as a workaround to avoid kernel inserting/deleting leap seconds by stepping the clock and possibly upsetting running applications. That no longer works with 4.2.6 as ntpd steps the clock itself when a leap second occurs.  The fix is to treat the one second offset gained during leap second as a normal offset and check the stepping threshold (set by -x or tinker step) to decide if a step should be applied.  See this forum post for more information on the Amazon Linux AMI's leap-second handling."); 
script_tag(name : "solution", value : "Run yum update ntp to update your system.");
script_tag(name : "solution_type", value : "VendorFix");
script_xref(name : "URL" , value : "https://alas.aws.amazon.com/ALAS-2015-520.html");
script_cve_id("CVE-2015-1798", "CVE-2015-1799");
script_tag(name:"cvss_base", value:"4.3");
script_tag(name:"cvss_base_vector", value:"AV:A/AC:M/Au:N/C:N/I:P/A:P");
script_tag(name:"qod_type", value:"package");
script_dependencies("gather-package-list.nasl");
script_mandatory_keys("ssh/login/amazon_linux", "ssh/login/release");
script_category(ACT_GATHER_INFO);
script_tag(name:"summary", value:"Amazon Linux Local Security Checks");
script_copyright("Eero Volotinen");
script_family("Amazon Linux Local Security Checks");
exit(0);
}
include("revisions-lib.inc");
include("pkg-lib-rpm.inc");
release = get_kb_item("ssh/login/release");
res = "";
if(release == NULL)
{
 exit(0);
}
if(release == "AMAZON")
{
if ((res = isrpmvuln(pkg:"ntp-debuginfo", rpm:"ntp-debuginfo~4.2.6p5~30.24.amzn1", rls:"AMAZON")) != NULL) {
  security_message(data:res);
  exit(0);
}
if ((res = isrpmvuln(pkg:"ntp", rpm:"ntp~4.2.6p5~30.24.amzn1", rls:"AMAZON")) != NULL) {
  security_message(data:res);
  exit(0);
}
if ((res = isrpmvuln(pkg:"ntp-doc", rpm:"ntp-doc~4.2.6p5~30.24.amzn1", rls:"AMAZON")) != NULL) {
  security_message(data:res);
  exit(0);
}
if ((res = isrpmvuln(pkg:"ntp-perl", rpm:"ntp-perl~4.2.6p5~30.24.amzn1", rls:"AMAZON")) != NULL) {
  security_message(data:res);
  exit(0);
}
if (__pkg_match) exit(99); #Not vulnerable
  exit(0);
}