An issue was discovered in zsh before 5.6. The beginning of a #! script file was mishandled, potentially leading to an execve call to a program named on the second line.(CVE-2018-0502)
It was discovered that zsh does not properly validate the shebang of input files and it truncates it to the first 64 bytes. A local attacker may use this flaw to make zsh execute a different binary than what is expected, named with a substring of the shebang one.(CVE-2018-13259)
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2018-1089.
#
include("compat.inc");
if (description)
{
script_id(118044);
script_version("1.3");
script_set_attribute(attribute:"plugin_modification_date", value:"2022/02/10");
script_cve_id("CVE-2018-0502", "CVE-2018-13259");
script_xref(name:"ALAS", value:"2018-1089");
script_name(english:"Amazon Linux 2 : zsh (ALAS-2018-1089)");
script_summary(english:"Checks rpm output for the updated packages");
script_set_attribute(
attribute:"synopsis",
value:"The remote Amazon Linux 2 host is missing a security update."
);
script_set_attribute(
attribute:"description",
value:
"An issue was discovered in zsh before 5.6. The beginning of a #!
script file was mishandled, potentially leading to an execve call to a
program named on the second line.(CVE-2018-0502)
It was discovered that zsh does not properly validate the shebang of
input files and it truncates it to the first 64 bytes. A local
attacker may use this flaw to make zsh execute a different binary than
what is expected, named with a substring of the shebang
one.(CVE-2018-13259)"
);
script_set_attribute(
attribute:"see_also",
value:"https://alas.aws.amazon.com/AL2/ALAS-2018-1089.html"
);
script_set_attribute(
attribute:"solution",
value:"Run 'yum update zsh' to update your system."
);
script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
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:H/I:H/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-2018-13259");
script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
script_set_attribute(attribute:"exploit_available", value:"false");
script_set_attribute(attribute:"plugin_type", value:"local");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:zsh");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:zsh-debuginfo");
script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:zsh-html");
script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
script_set_attribute(attribute:"vuln_publication_date", value:"2018/09/05");
script_set_attribute(attribute:"patch_publication_date", value:"2018/10/08");
script_set_attribute(attribute:"plugin_publication_date", value:"2018/10/11");
script_set_attribute(attribute:"generated_plugin", value:"current");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_copyright(english:"This script is Copyright (C) 2018-2022 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 != "2")
{
if (os_ver == 'A') os_ver = 'AMI';
audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}
if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
flag = 0;
if (rpm_check(release:"AL2", reference:"zsh-5.5.1-2.amzn2.0.1")) flag++;
if (rpm_check(release:"AL2", reference:"zsh-debuginfo-5.5.1-2.amzn2.0.1")) flag++;
if (rpm_check(release:"AL2", reference:"zsh-html-5.5.1-2.amzn2.0.1")) flag++;
if (flag)
{
if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get());
else security_hole(0);
exit(0);
}
else
{
tested = pkg_tests_get();
if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
else audit(AUDIT_PACKAGE_NOT_INSTALLED, "zsh / zsh-debuginfo / zsh-html");
}