Vulnerabilities > CVE-2019-6690 - Improper Input Validation vulnerability in multiple products

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
HIGH
Availability impact
NONE
network
low complexity
python
debian
opensuse
suse
canonical
CWE-20
nessus
NVD
Published: 2019-03-21
Updated: 2023-11-07

Summary

python-gnupg 0.4.3 allows context-dependent attackers to trick gnupg to decrypt other ciphertext than intended. To perform the attack, the passphrase to gnupg must be controlled by the adversary and the ciphertext should be trusted. Related to a "CWE-20: Improper Input Validation" issue affecting the affect functionality component.

Vulnerable Configurations

Part Description Count
Application
Python
1
Application
Suse
1
OS
Debian
2
OS
Opensuse
1
OS
Suse
1
OS
Canonical
3

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

Nessus

  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-3964-1.NASL
    descriptionMarcus Brinkmann discovered that GnuPG before 2.2.8 improperly handled certain command line parameters. A remote attacker could use this to spoof the output of GnuPG and cause unsigned e-mail to appear signed. (CVE-2018-12020) It was discovered that python-gnupg incorrectly handled the GPG passphrase. A remote attacker could send a specially crafted passphrase that would allow them to control the output of encryption and decryption operations. (CVE-2019-6690). 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.
    last seen2020-06-01
    modified2020-06-02
    plugin id124587
    published2019-05-03
    reporterUbuntu Security Notice (C) 2019 Canonical, Inc. / NASL script (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/124587
    titleUbuntu 18.04 LTS / 18.10 / 19.04 : python-gnupg vulnerabilities (USN-3964-1)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3964-1. 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(124587);
  script_version("1.3");
  script_cvs_date("Date: 2019/09/18 12:31:49");

  script_cve_id("CVE-2018-12020", "CVE-2019-6690");
  script_xref(name:"USN", value:"3964-1");

  script_name(english:"Ubuntu 18.04 LTS / 18.10 / 19.04 : python-gnupg vulnerabilities (USN-3964-1)");
  script_summary(english:"Checks dpkg output for updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Ubuntu host is missing one or more security-related
patches."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Marcus Brinkmann discovered that GnuPG before 2.2.8 improperly handled
certain command line parameters. A remote attacker could use this to
spoof the output of GnuPG and cause unsigned e-mail to appear signed.
(CVE-2018-12020)

It was discovered that python-gnupg incorrectly handled the GPG
passphrase. A remote attacker could send a specially crafted
passphrase that would allow them to control the output of encryption
and decryption operations. (CVE-2019-6690).

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/3964-1/"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected python-gnupg and / or python3-gnupg packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/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:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python-gnupg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-gnupg");
  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:18.10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:19.04");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/06/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/02");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/05/03");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2019 Canonical, Inc. / NASL script (C) 2019 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|18\.10|19\.04)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 18.04 / 18.10 / 19.04", "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:"python-gnupg", pkgver:"0.4.1-1ubuntu1.18.04.1")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"python3-gnupg", pkgver:"0.4.1-1ubuntu1.18.04.1")) flag++;
if (ubuntu_check(osver:"18.10", pkgname:"python-gnupg", pkgver:"0.4.1-1ubuntu1.18.10.1")) flag++;
if (ubuntu_check(osver:"18.10", pkgname:"python3-gnupg", pkgver:"0.4.1-1ubuntu1.18.10.1")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python-gnupg", pkgver:"0.4.3-1ubuntu1.19.04.1")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python3-gnupg", pkgver:"0.4.3-1ubuntu1.19.04.1")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    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, "python-gnupg / python3-gnupg");
}
  • NASL familySuSE Local Security Checks
    NASL idOPENSUSE-2019-143.NASL
    descriptionThis update for python-python-gnupg to version 0.4.4 fixes the following issues : Security issue fixed : - CVE-2019-6690: Added a check to disallow certain control characters (
    last seen2020-06-01
    modified2020-06-02
    plugin id121634
    published2019-02-07
    reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/121634
    titleopenSUSE Security Update : python-python-gnupg (openSUSE-2019-143)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from openSUSE Security Update openSUSE-2019-143.
#
# The text description of this plugin is (C) SUSE LLC.
#

include("compat.inc");

if (description)
{
  script_id(121634);
  script_version("1.4");
  script_cvs_date("Date: 2019/04/08 10:48:58");

  script_cve_id("CVE-2019-6690");

  script_name(english:"openSUSE Security Update : python-python-gnupg (openSUSE-2019-143)");
  script_summary(english:"Check for the openSUSE-2019-143 patch");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote openSUSE host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"This update for python-python-gnupg to version 0.4.4 fixes the
following issues :

Security issue fixed :

  - CVE-2019-6690: Added a check to disallow certain control
    characters ('\r', '\n', NUL) in passphrases
    (boo#1123498)."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.opensuse.org/show_bug.cgi?id=1123498"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected python-python-gnupg packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/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:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:python2-python-gnupg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:python3-python-gnupg");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:opensuse:15.0");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/21");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/03/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/02/07");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"SuSE Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/SuSE/release", "Host/SuSE/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/SuSE/release");
if (isnull(release) || release =~ "^(SLED|SLES)") audit(AUDIT_OS_NOT, "openSUSE");
if (release !~ "^(SUSE15\.0)$") audit(AUDIT_OS_RELEASE_NOT, "openSUSE", "15.0", release);
if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);



flag = 0;

if ( rpm_check(release:"SUSE15.0", reference:"python2-python-gnupg-0.4.4-lp150.2.6.1") ) flag++;
if ( rpm_check(release:"SUSE15.0", reference:"python3-python-gnupg-0.4.4-lp150.2.6.1") ) 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, "python2-python-gnupg / python3-python-gnupg");
}
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-1675.NASL
    descriptionAlexander Kj&auml;ll and Stig Palmquist discovered a vulnerability in python-gnupg, a wrapper around GNU Privacy Guard. It was possible to inject data through the passphrase property of the gnupg.GPG.encrypt() and gnupg.GPG.decrypt() functions when symmetric encryption is used. The supplied passphrase is not validated for newlines, and the library passes --passphrase-fd=0 to the gpg executable, which expects the passphrase on the first line of stdin, and the ciphertext to be decrypted or plaintext to be encrypted on subsequent lines. By supplying a passphrase containing a newline an attacker can control/modify the ciphertext/plaintext being decrypted/encrypted. For Debian 8
    last seen2020-06-01
    modified2020-06-02
    plugin id122195
    published2019-02-15
    reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/122195
    titleDebian DLA-1675-1 : python-gnupg security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory DLA-1675-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(122195);
  script_version("1.4");
  script_cvs_date("Date: 2019/04/08 10:48:58");

  script_cve_id("CVE-2019-6690");

  script_name(english:"Debian DLA-1675-1 : python-gnupg security update");
  script_summary(english:"Checks dpkg output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Alexander Kj&auml;ll and Stig Palmquist discovered a vulnerability in
python-gnupg, a wrapper around GNU Privacy Guard. It was possible to
inject data through the passphrase property of the gnupg.GPG.encrypt()
and gnupg.GPG.decrypt() functions when symmetric encryption is used.
The supplied passphrase is not validated for newlines, and the library
passes --passphrase-fd=0 to the gpg executable, which expects the
passphrase on the first line of stdin, and the ciphertext to be
decrypted or plaintext to be encrypted on subsequent lines.

By supplying a passphrase containing a newline an attacker can
control/modify the ciphertext/plaintext being decrypted/encrypted.

For Debian 8 'Jessie', this problem has been fixed in version
0.3.6-1+deb8u1.

We recommend that you upgrade your python-gnupg packages.

NOTE: Tenable Network Security has extracted the preceding description
block directly from the DLA 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://lists.debian.org/debian-lts-announce/2019/02/msg00021.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/jessie/python-gnupg"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Upgrade the affected python-gnupg, and python3-gnupg packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/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:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python-gnupg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python3-gnupg");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:8.0");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/21");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/02/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/02/15");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Debian Local Security Checks");

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

  exit(0);
}


include("audit.inc");
include("debian_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (deb_check(release:"8.0", prefix:"python-gnupg", reference:"0.3.6-1+deb8u1")) flag++;
if (deb_check(release:"8.0", prefix:"python3-gnupg", reference:"0.3.6-1+deb8u1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:deb_report_get());
  else security_warning(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");

References