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nessusUbuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.UBUNTU_USN-5200-1.NASL
HistoryDec 18, 2021 - 12:00 a.m.

Ubuntu 18.04 LTS : Python vulnerabilities (USN-5200-1)

2021-12-1800:00:00
Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
34
ubuntu 18.04 lts
python vulnerabilities
usn-5200-1
regular expression denial of service
urllib
abstractbasicauthhandler
cve-2020-8492
cve-2021-3733
cve-2021-3737
http server
http client
cpu consumption

CVSS2

7.1

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

COMPLETE

AV:N/AC:M/Au:N/C:N/I:N/A:C

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

AI Score

8

Confidence

High

EPSS

0.016

Percentile

87.3%

The remote Ubuntu 18.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5200-1 advisory.

It was discovered that the urllib.request.AbstractBasicAuthHandler class

in Python contains regex allowing for catastrophic backtracking. Specially

crafted traffic from a malicious HTTP server could cause a regular expression

denial of service (ReDoS) condition for a client. (CVE-2020-8492)

It was discovered that the urllib.request.AbstractBasicAuthHandler class

in Python contains regex with a quadratic worst-case time complexity.

Specially crafted traffic from a malicious HTTP server could cause a regular

expression denial of service (ReDoS) condition for a client. (CVE-2021-3733)

It was discovered that the Python urllib http client could enter into an infinite

loop when incorrectly handling certain server responses (100 Continue response).

Specially crafted traffic from a malicious HTTP server could cause a denial of

service (DoS) condition for a client. (CVE-2021-3737)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application’s self-reported version number.

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-5200-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(156171);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id("CVE-2020-8492", "CVE-2021-3733", "CVE-2021-3737");
  script_xref(name:"USN", value:"5200-1");
  script_xref(name:"IAVA", value:"2020-A-0103-S");
  script_xref(name:"IAVA", value:"2021-A-0497-S");

  script_name(english:"Ubuntu 18.04 LTS : Python vulnerabilities (USN-5200-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 18.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in
the USN-5200-1 advisory.

    It was discovered that the urllib.request.AbstractBasicAuthHandler class

    in Python contains regex allowing for catastrophic backtracking. Specially

    crafted traffic from a malicious HTTP server could cause a regular expression

    denial of service (ReDoS) condition for a client. (CVE-2020-8492)

    It was discovered that the urllib.request.AbstractBasicAuthHandler class

    in Python contains regex with a quadratic worst-case time complexity.

    Specially crafted traffic from a malicious HTTP server could cause a regular

    expression denial of service (ReDoS) condition for a client. (CVE-2021-3733)

    It was discovered that the Python urllib http client could enter into an infinite

    loop when incorrectly handling certain server responses (100 Continue response).

    Specially crafted traffic from a malicious HTTP server could cause a denial of

    service (DoS) condition for a client. (CVE-2021-3737)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-5200-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-2021-3737");

  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:"2020/01/30");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/12/17");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/12/18");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:idle-python3.7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:idle-python3.8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.7-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.7-minimal");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.7-stdlib");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.7-testsuite");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.8-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.8-minimal");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.8-stdlib");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpython3.8-testsuite");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7-examples");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7-minimal");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.7-venv");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8-examples");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8-minimal");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3.8-venv");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('18.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 18.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '18.04', 'pkgname': 'idle-python3.7', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'idle-python3.8', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.7', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.7-dev', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.7-minimal', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.7-stdlib', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.7-testsuite', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.8', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.8-dev', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.8-minimal', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.8-stdlib', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'libpython3.8-testsuite', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.7', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.7-dev', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.7-examples', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.7-minimal', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.7-venv', 'pkgver': '3.7.5-2ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.8', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.8-dev', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.8-examples', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.8-minimal', 'pkgver': '3.8.0-3ubuntu1~18.04.2'},
    {'osver': '18.04', 'pkgname': 'python3.8-venv', 'pkgver': '3.8.0-3ubuntu1~18.04.2'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'idle-python3.7 / idle-python3.8 / libpython3.7 / libpython3.7-dev / etc');
}

CVSS2

7.1

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

COMPLETE

AV:N/AC:M/Au:N/C:N/I:N/A:C

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

AI Score

8

Confidence

High

EPSS

0.016

Percentile

87.3%