Amazon Linux: Security Advisory (ALAS-2015-520)

# SPDX-FileCopyrightText: 2015 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.120060");
  script_cve_id("CVE-2015-1798", "CVE-2015-1799");
  script_tag(name:"creation_date", value:"2015-09-08 11:16:30 +0000 (Tue, 08 Sep 2015)");
  script_version("2025-01-23T05:37:38+0000");
  script_tag(name:"last_modification", value:"2025-01-23 05:37:38 +0000 (Thu, 23 Jan 2025)");
  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_name("Amazon Linux: Security Advisory (ALAS-2015-520)");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2015 Greenbone AG");
  script_family("Amazon Linux Local Security Checks");
  script_dependencies("gather-package-list.nasl");
  script_mandatory_keys("ssh/login/amazon_linux", "ssh/login/release");

  script_xref(name:"Advisory-ID", value:"ALAS-2015-520");
  script_xref(name:"URL", value:"https://alas.aws.amazon.com/ALAS-2015-520.html");
  script_xref(name:"URL", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1196635");
  script_xref(name:"URL", value:"https://forums.aws.amazon.com/ann.jspa?annID=3064");

  script_tag(name:"summary", value:"The remote host is missing an update for the 'ntp' package(s) announced via the ALAS-2015-520 advisory.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable package version is present on the target host.");

  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:"affected", value:"'ntp' package(s) on Amazon Linux.");

  script_tag(name:"solution", value:"Please install the updated package(s).");

  script_tag(name:"solution_type", value:"VendorFix");
  script_tag(name:"qod_type", value:"package");

  exit(0);
}

include("revisions-lib.inc");
include("pkg-lib-rpm.inc");

release = rpm_get_ssh_release();
if(!release)
  exit(0);

res = "";
report = "";

if(release == "AMAZON") {

  if(!isnull(res = isrpmvuln(pkg:"ntp", rpm:"ntp~4.2.6p5~30.24.amzn1", rls:"AMAZON"))) {
    report += res;
  }

  if(!isnull(res = isrpmvuln(pkg:"ntp-debuginfo", rpm:"ntp-debuginfo~4.2.6p5~30.24.amzn1", rls:"AMAZON"))) {
    report += res;
  }

  if(!isnull(res = isrpmvuln(pkg:"ntp-doc", rpm:"ntp-doc~4.2.6p5~30.24.amzn1", rls:"AMAZON"))) {
    report += res;
  }

  if(!isnull(res = isrpmvuln(pkg:"ntp-perl", rpm:"ntp-perl~4.2.6p5~30.24.amzn1", rls:"AMAZON"))) {
    report += res;
  }

  if(!isnull(res = isrpmvuln(pkg:"ntpdate", rpm:"ntpdate~4.2.6p5~30.24.amzn1", rls:"AMAZON"))) {
    report += res;
  }

  if(report != "") {
    security_message(data:report);
  } else if(__pkg_match) {
    exit(99);
  }
  exit(0);
}

exit(0);