Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) - Nessus

Critical Plugin ID: 134299

This page contains detailed information about the Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) Nessus plugin including available exploits and PoCs found on GitHub, in Metasploit or Exploit-DB for verifying of this vulnerability.

Table Of Contents

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Plugin Overview
Vulnerability Information

Synopsis
Description
Solution

Public Exploits
Risk Information
Plugin Source
How to Run
References
Version

Plugin Overview

ID: 134299
Name: Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1)
Filename: ubuntu_USN-4294-1.nasl
Vulnerability Published: 2020-02-25
This Plugin Published: 2020-03-06
Last Modification Time: 2020-03-10
Plugin Version: 1.2
Plugin Type: local
Plugin Family: Ubuntu Local Security Checks
Dependencies: ssh_get_info.nasl
Required KB Items [?]: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Vulnerability Information

Severity: Critical
Vulnerability Published: 2020-02-25
Patch Published: 2020-03-02
CVE [?]: CVE-2020-8793, CVE-2020-8794
CPE [?]: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:19.10, p-cpe:/a:canonical:ubuntu_linux:opensmtpd

Synopsis

The remote Ubuntu host is missing a security-related patch.

Description

It was discovered that OpenSMTPD mishandled certain input. A remote, unauthenticated attacker could use this vulnerability to execute arbitrary shell commands as any non-root user. (CVE-2020-8794)

It was discovered that OpenSMTPD did not properly handle hardlinks under certain conditions. An unprivileged local attacker could read the first line of any file on the filesystem. (CVE-2020-8793).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Solution

Update the affected opensmtpd package.

Public Exploits

Target Network Port(s): N/A
Target Asset(s): N/A
Exploit Available: True (Metasploit Framework, Exploit-DB, GitHub)
Exploit Ease: Exploits are available

Here's the list of publicly known exploits and PoCs for verifying the Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) vulnerability:

Metasploit: exploit/unix/local/opensmtpd_oob_read_lpe
[OpenSMTPD OOB Read Local Privilege Escalation]
Exploit-DB: exploits/linux/local/48185.rb
[EDB-48185: OpenSMTPD - OOB Read Local Privilege Escalation (Metasploit)]
Exploit-DB: exploits/linux/remote/48139.c
[EDB-48139: OpenSMTPD 6.6.3 - Arbitrary File Read]
Exploit-DB: exploits/openbsd/remote/48140.c
[EDB-48140: OpenSMTPD < 6.6.3p1 - Local Privilege Escalation + Remote Code Execution]
GitHub: https://github.com/rpie/OpenSMTPD
[CVE-2020-8793: A mass exploitation tool for CVE 2020-8793]
GitHub: https://github.com/Mr-xn/Penetration_Testing_POC
[CVE-2020-8794]

Before running any exploit against any system, make sure you are authorized by the owner of the target system(s) to perform such activity. In any other case, this would be considered as an illegal activity.

WARNING: Beware of using unverified exploits from sources such as GitHub or Exploit-DB. These exploits and PoCs could contain malware. For more information, see how to use exploits safely.

Risk Information

CVSS V2 Vector [?]: AV:N/AC:L/Au:N/C:C/I:C/A:C/E:F/RL:OF/RC:C

CVSS Base Score:	10.0 (High)
Impact Subscore:	10.0
Exploitability Subscore:	10.0
CVSS Temporal Score:	8.3 (High)
CVSS Environmental Score:	NA (None)
Modified Impact Subscore:	NA
Overall CVSS Score:	8.3 (High)

CVSS V3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

CVSS Base Score:	9.8 (Critical)
Impact Subscore:	5.9
Exploitability Subscore:	3.9
CVSS Temporal Score:	9.1 (Critical)
CVSS Environmental Score:	NA (None)
Modified Impact Subscore:	NA
Overall CVSS Score:	9.1 (Critical)

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Plugin Source

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4294-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include("compat.inc");

if (description)
{
  script_id(134299);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/10");

  script_cve_id("CVE-2020-8793", "CVE-2020-8794");
  script_xref(name:"USN", value:"4294-1");

  script_name(english:"Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1)");
  script_summary(english:"Checks dpkg output for updated package.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Ubuntu host is missing a security-related patch."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"It was discovered that OpenSMTPD mishandled certain input. A remote,
unauthenticated attacker could use this vulnerability to execute
arbitrary shell commands as any non-root user. (CVE-2020-8794)

It was discovered that OpenSMTPD did not properly handle hardlinks
under certain conditions. An unprivileged local attacker could read
the first line of any file on the filesystem. (CVE-2020-8793).

Note that Tenable Network Security has extracted the preceding
description block directly from the Ubuntu security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://usn.ubuntu.com/4294-1/"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected opensmtpd package."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:F/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:F/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'OpenSMTPD OOB Read Local Privilege Escalation');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:opensmtpd");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:19.10");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/02/25");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/03/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/03/06");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Ubuntu Local Security Checks");

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

  exit(0);
}


include("audit.inc");
include("ubuntu.inc");
include("misc_func.inc");

if ( ! get_kb_item("Host/local_checks_enabled") ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/Ubuntu/release");
if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu");
release = chomp(release);
if (! preg(pattern:"^(18\.04|19\.10)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 18.04 / 19.10", "Ubuntu " + release);
if ( ! get_kb_item("Host/Debian/dpkg-l") ) 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, "Ubuntu", cpu);

flag = 0;

if (ubuntu_check(osver:"18.04", pkgname:"opensmtpd", pkgver:"6.0.3p1-1ubuntu0.2")) flag++;
if (ubuntu_check(osver:"19.10", pkgname:"opensmtpd", pkgver:"6.0.3p1-6ubuntu0.2")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "opensmtpd");
}

The latest version of this script can be found in these locations depending on your platform:

Linux / Unix:
/opt/nessus/lib/nessus/plugins/ubuntu_USN-4294-1.nasl
Windows:
C:\ProgramData\Tenable\Nessus\nessus\plugins\ubuntu_USN-4294-1.nasl
Mac OS X:
/Library/Nessus/run/lib/nessus/plugins/ubuntu_USN-4294-1.nasl

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How to Run

Here is how to run the Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) as a standalone plugin via the Nessus web user interface (https://localhost:8834/):

Click to start a New Scan.
Select Advanced Scan.
Navigate to the Plugins tab.
On the top right corner click to Disable All plugins.
On the left side table select Ubuntu Local Security Checks plugin family.
On the right side table select Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) plugin ID 134299.
Specify the target on the Settings tab and click to Save the scan.
Run the scan.

Here are a few examples of how to run the plugin in the command line. Note that the examples below demonstrate the usage on the Linux / Unix platform.

Basic usage:

/opt/nessus/bin/nasl ubuntu_USN-4294-1.nasl -t <IP/HOST>

Run the plugin with audit trail message on the console:

/opt/nessus/bin/nasl -a ubuntu_USN-4294-1.nasl -t <IP/HOST>

Run the plugin with trace script execution written to the console (useful for debugging):

/opt/nessus/bin/nasl -T - ubuntu_USN-4294-1.nasl -t <IP/HOST>

Run the plugin with using a state file for the target and updating it (useful for running multiple plugins on the target):

/opt/nessus/bin/nasl -K /tmp/state ubuntu_USN-4294-1.nasl -t <IP/HOST>

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References

USN | Ubuntu Security Notice:

4294-1

See also:

Similar and related Nessus plugins:

134094 - Debian DSA-4634-1 : opensmtpd - security update
133970 - FreeBSD : OpenSMTPd -- LPE and RCE in OpenSMTPD's default install (40c75597-574a-11ea-bff8-c85b76ce9b5a)
133971 - FreeBSD : OpenSMTPd -- Local information disclosure (76f1ce19-5749-11ea-bff8-c85b76ce9b5a)
133973 - FreeBSD : OpenSMTPd -- LPE and RCE in OpenSMTPD's default install (f0683976-5779-11ea-8a77-1c872ccb1e42)

Version

This page has been produced using Nessus Professional 10.1.2 (#68) LINUX, Plugin set 202205072148.
Plugin file ubuntu_USN-4294-1.nasl version 1.2. For more plugins, visit the Nessus Plugin Library.

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Ubuntu 18.04 LTS / 19.10 : OpenSMTPD vulnerabilities (USN-4294-1) - Nessus

Plugin Overview

Vulnerability Information

Synopsis

Description

Solution

Public Exploits

Risk Information

Plugin Source

How to Run

References

Version

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