Vulnerabilities > CVE-2018-20969 - OS Command Injection vulnerability in GNU Patch

#
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were
# extracted from ZTE advisory NS-SA-2019-0253. The text
# itself is copyright (C) ZTE, Inc.

include('compat.inc');

if (description)
{
  script_id(132496);
  script_version("1.2");
  script_cvs_date("Date: 2020/01/02");

  script_cve_id(
    "CVE-2016-10713",
    "CVE-2018-6952",
    "CVE-2018-20969",
    "CVE-2019-13638"
  );
  script_bugtraq_id(103047, 103063);

  script_name(english:"NewStart CGSL CORE 5.05 / MAIN 5.05 : patch Multiple Vulnerabilities (NS-SA-2019-0253)");

  script_set_attribute(attribute:"synopsis", value:
"The remote machine is affected by multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The remote NewStart CGSL host, running version CORE 5.05 / MAIN 5.05, has patch packages installed that are affected by
multiple vulnerabilities:

  - An issue was discovered in GNU patch before 2.7.6. Out-
    of-bounds access within pch_write_line() in pch.c can
    possibly lead to DoS via a crafted input file.
    (CVE-2016-10713)

  - A double free exists in the another_hunk function in
    pch.c in GNU patch through 2.7.6. (CVE-2018-6952)

  - GNU patch through 2.7.6 is vulnerable to OS shell
    command injection that can be exploited by opening a
    crafted patch file that contains an ed style diff
    payload with shell metacharacters. The ed editor does
    not need to be present on the vulnerable system. This is
    different from CVE-2018-1000156. (CVE-2019-13638)

  - do_ed_script in pch.c in GNU patch through 2.7.6 does
    not block strings beginning with a ! character. NOTE:
    this is the same commit as for CVE-2019-13638, but the !
    syntax is specific to ed, and is unrelated to a shell
    metacharacter. (CVE-2018-20969)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"http://security.gd-linux.com/notice/NS-SA-2019-0253");
  script_set_attribute(attribute:"solution", value:
"Upgrade the vulnerable CGSL patch packages. Note that updated packages may not be available yet. Please contact ZTE for
more information.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-13638");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/02/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/12/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/12/31");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"NewStart CGSL Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/ZTE-CGSL/release", "Host/ZTE-CGSL/rpm-list", "Host/cpu");

  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/ZTE-CGSL/release");
if (isnull(release) || release !~ "^CGSL (MAIN|CORE)") audit(AUDIT_OS_NOT, "NewStart Carrier Grade Server Linux");

if (release !~ "CGSL CORE 5.05" &&
    release !~ "CGSL MAIN 5.05")
  audit(AUDIT_OS_NOT, 'NewStart CGSL CORE 5.05 / NewStart CGSL MAIN 5.05');

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

cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "NewStart Carrier Grade Server Linux", cpu);

flag = 0;

pkgs = {
  "CGSL CORE 5.05": [
    "patch-2.7.1-12.el7_7",
    "patch-debuginfo-2.7.1-12.el7_7"
  ],
  "CGSL MAIN 5.05": [
    "patch-2.7.1-12.el7_7",
    "patch-debuginfo-2.7.1-12.el7_7"
  ]
};
pkg_list = pkgs[release];

foreach (pkg in pkg_list)
  if (rpm_check(release:"ZTE " + release, reference:pkg)) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "patch");
}