The yaml_parser_scan_tag_uri function in scanner.c in LibYAML before 0.1.5 performs an incorrect cast, which allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via crafted tags in a YAML document, which triggers a heap-based buffer overflow.
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2014-291.
#
include("compat.inc");
if (description)
{
script_id(72747);
script_version("1.4");
script_cvs_date("Date: 2018/04/18 15:09:35");
script_cve_id("CVE-2013-6393");
script_xref(name:"ALAS", value:"2014-291");
script_name(english:"Amazon Linux AMI : libyaml (ALAS-2014-291)");
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:
"The yaml_parser_scan_tag_uri function in scanner.c in LibYAML before
0.1.5 performs an incorrect cast, which allows remote attackers to
cause a denial of service (application crash) and possibly execute
arbitrary code via crafted tags in a YAML document, which triggers a
heap-based buffer overflow."
);
script_set_attribute(
attribute:"see_also",
value:"https://alas.aws.amazon.com/ALAS-2014-291.html"
);
script_set_attribute(
attribute:"solution",
value:"Run 'yum update libyaml' to update your system."
);
script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libyaml");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libyaml-debuginfo");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:libyaml-devel");
script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");
script_set_attribute(attribute:"patch_publication_date", value:"2014/02/26");
script_set_attribute(attribute:"plugin_publication_date", value:"2014/03/02");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_copyright(english:"This script is Copyright (C) 2014-2018 Tenable Network Security, Inc.");
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:"libyaml-0.1.4-6.5.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"libyaml-debuginfo-0.1.4-6.5.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"libyaml-devel-0.1.4-6.5.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, "libyaml / libyaml-debuginfo / libyaml-devel");
}