Vulnerabilities > CVE-2015-6817 - Improper Authentication vulnerability in Pgbouncer 1.6

047910
CVSS 6.8 - MEDIUM
Attack vector
NETWORK
Attack complexity
MEDIUM
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
PARTIAL
Availability impact
PARTIAL
network
pgbouncer
CWE-287
nessus

Summary

PgBouncer 1.6.x before 1.6.1, when configured with auth_user, allows remote attackers to gain login access as auth_user via an unknown username.

Vulnerable Configurations

Part Description Count
Application
Pgbouncer
1

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Authentication Abuse
    An attacker obtains unauthorized access to an application, service or device either through knowledge of the inherent weaknesses of an authentication mechanism, or by exploiting a flaw in the authentication scheme's implementation. In such an attack an authentication mechanism is functioning but a carefully controlled sequence of events causes the mechanism to grant access to the attacker. This attack may exploit assumptions made by the target's authentication procedures, such as assumptions regarding trust relationships or assumptions regarding the generation of secret values. This attack differs from Authentication Bypass attacks in that Authentication Abuse allows the attacker to be certified as a valid user through illegitimate means, while Authentication Bypass allows the user to access protected material without ever being certified as an authenticated user. This attack does not rely on prior sessions established by successfully authenticating users, as relied upon for the "Exploitation of Session Variables, Resource IDs and other Trusted Credentials" attack patterns.
  • Exploiting Trust in Client (aka Make the Client Invisible)
    An attack of this type exploits a programs' vulnerabilities in client/server communication channel authentication and data integrity. It leverages the implicit trust a server places in the client, or more importantly, that which the server believes is the client. An attacker executes this type of attack by placing themselves in the communication channel between client and server such that communication directly to the server is possible where the server believes it is communicating only with a valid client. There are numerous variations of this type of attack.
  • Utilizing REST's Trust in the System Resource to Register Man in the Middle
    This attack utilizes a REST(REpresentational State Transfer)-style applications' trust in the system resources and environment to place man in the middle once SSL is terminated. Rest applications premise is that they leverage existing infrastructure to deliver web services functionality. An example of this is a Rest application that uses HTTP Get methods and receives a HTTP response with an XML document. These Rest style web services are deployed on existing infrastructure such as Apache and IIS web servers with no SOAP stack required. Unfortunately from a security standpoint, there frequently is no interoperable identity security mechanism deployed, so Rest developers often fall back to SSL to deliver security. In large data centers, SSL is typically terminated at the edge of the network - at the firewall, load balancer, or router. Once the SSL is terminated the HTTP request is in the clear (unless developers have hashed or encrypted the values, but this is rare). The attacker can utilize a sniffer such as Wireshark to snapshot the credentials, such as username and password that are passed in the clear once SSL is terminated. Once the attacker gathers these credentials, they can submit requests to the web service provider just as authorized user do. There is not typically an authentication on the client side, beyond what is passed in the request itself so once this is compromised, then this is generally sufficient to compromise the service's authentication scheme.
  • Man in the Middle Attack
    This type of attack targets the communication between two components (typically client and server). The attacker places himself in the communication channel between the two components. Whenever one component attempts to communicate with the other (data flow, authentication challenges, etc.), the data first goes to the attacker, who has the opportunity to observe or alter it, and it is then passed on to the other component as if it was never intercepted. This interposition is transparent leaving the two compromised components unaware of the potential corruption or leakage of their communications. The potential for Man-in-the-Middle attacks yields an implicit lack of trust in communication or identify between two components.

Nessus

  • NASL familyMisc.
    NASL idPGBOUNCER_1_6_AUTH_BYPASS.NASL
    descriptionThe version of Pgbouncer running on the remote host is affected by an authentication bypass vulnerability due to a flaw in the start_auth_request() function within file client.c when handling requests for invalid users. A remote attacker can exploit this issue to bypass authentication and log into PostgreSQL via Pgbouncer using a random user name.
    last seen2020-06-01
    modified2020-06-02
    plugin id93006
    published2016-08-17
    reporterThis script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/93006
    titlePgbouncer 1.6 Invalid User Authentication Bypass
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(93006);
      script_version("1.6");
      script_cvs_date("Date: 2019/11/19");
    
      script_cve_id("CVE-2015-6817");
    
      script_name(english:"Pgbouncer 1.6 Invalid User Authentication Bypass");
      script_summary(english:"Attempts to log in through Pgbouncer using a random user name.");
    
      script_set_attribute(attribute:"synopsis", value:
    "The remote database connection pooler is affected by an
    authentication bypass vulnerability.");
      script_set_attribute(attribute:"description", value:
    "The version of Pgbouncer running on the remote host is affected by an
    authentication bypass vulnerability due to a flaw in the
    start_auth_request() function within file client.c when handling
    requests for invalid users. A remote attacker can exploit this issue
    to bypass authentication and log into PostgreSQL via Pgbouncer using a
    random user name.");
      script_set_attribute(attribute:"see_also", value:"https://seclists.org/oss-sec/2015/q3/495");
      script_set_attribute(attribute:"see_also", value:"https://github.com/pgbouncer/pgbouncer/issues/69");
      # https://web.archive.org/web/20150911232806/http://comments.gmane.org/gmane.comp.db.postgresql.pgbouncer.general/1251
      script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?342233a3");
      script_set_attribute(attribute:"solution", value:
    "Upgrade to Pgbouncer version 1.6.1 or later. Alternatively, disable
    'auth_user' in the Pgbouncer configuration.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/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:H/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-2015-6817");
    
      script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
      script_set_attribute(attribute:"exploit_available", value:"false");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2015/08/27");
      script_set_attribute(attribute:"patch_publication_date", value:"2015/09/03");
      script_set_attribute(attribute:"plugin_publication_date", value:"2016/08/17");
    
      script_set_attribute(attribute:"plugin_type", value:"remote");
      script_set_attribute(attribute:"cpe", value:"x-cpe:/a:pgbouncer:pgbouncer");
      script_end_attributes();
    
      script_category(ACT_ATTACK);
      script_family(english:"Misc.");
    
      script_copyright(english:"This script is Copyright (C) 2016-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
    
      script_dependencies("pgbouncer_detect.nbin");
      script_exclude_keys("global_settings/supplied_logins_only");
      script_require_ports("Services/pgbouncer", 5432, 6432);
    
      exit(0);
    }
    
    include("audit.inc");
    include("global_settings.inc");
    include("misc_func.inc");
    include("pgbouncer_func.inc");
    
    app = 'pgbouncer';
    port = get_service(svc:"pgbouncer", exit_on_fail:TRUE);
    
    if (!get_port_state(port)) audit(AUDIT_NOT_LISTEN, app, port);
    
    if (supplied_logins_only) audit(AUDIT_SUPPLIED_LOGINS_ONLY);
    
    user = rand_str(length:16); # generate random user name
    res = pgbouncer_login(port:port, user:user, database:'postgres');
    
    # look for indication of successful login
    if (!empty_or_null(res) &&
        "server_version" >< res &&
        "is_superuser" >< res &&
        "application_name" >< res
      )
    {
      report =
        '\n  Nessus was able to log into PostgreSQL via Pgbouncer using' +
        '\n  the following randomly generated user name:' +
        '\n    ' + user;
      security_report_v4(port:port, severity:SECURITY_WARNING, extra:report);
      exit(0);
    }
    else audit(AUDIT_LISTEN_NOT_VULN, app, port);
    
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_D76961DA56F611E5934B002590263BF5.NASL
    descriptionPgBouncer reports : New auth_user functionality introduced in 1.6 allows login as auth_user when client presents unknown username. It
    last seen2020-06-01
    modified2020-06-02
    plugin id85894
    published2015-09-10
    reporterThis script is Copyright (C) 2015-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/85894
    titleFreeBSD : pgbouncer -- failed auth_query lookup leads to connection as auth_user (d76961da-56f6-11e5-934b-002590263bf5)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from the FreeBSD VuXML database :
    #
    # Copyright 2003-2018 Jacques Vidrine and contributors
    #
    # Redistribution and use in source (VuXML) and 'compiled' forms (SGML,
    # HTML, PDF, PostScript, RTF and so forth) with or without modification,
    # are permitted provided that the following conditions are met:
    # 1. Redistributions of source code (VuXML) must retain the above
    #    copyright notice, this list of conditions and the following
    #    disclaimer as the first lines of this file unmodified.
    # 2. Redistributions in compiled form (transformed to other DTDs,
    #    published online in any format, converted to PDF, PostScript,
    #    RTF and other formats) must reproduce the above copyright
    #    notice, this list of conditions and the following disclaimer
    #    in the documentation and/or other materials provided with the
    #    distribution.
    # 
    # THIS DOCUMENTATION IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"
    # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
    # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
    # BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
    # OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
    # OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
    # BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
    # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
    # OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION,
    # EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(85894);
      script_version("2.5");
      script_cvs_date("Date: 2018/11/23 12:49:57");
    
      script_cve_id("CVE-2015-6817");
    
      script_name(english:"FreeBSD : pgbouncer -- failed auth_query lookup leads to connection as auth_user (d76961da-56f6-11e5-934b-002590263bf5)");
      script_summary(english:"Checks for updated package in pkg_info output");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote FreeBSD host is missing a security-related update."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "PgBouncer reports :
    
    New auth_user functionality introduced in 1.6 allows login as
    auth_user when client presents unknown username. It's quite likely
    auth_user is superuser. Affects only setups that have enabled
    auth_user in their config."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://pgbouncer.github.io/2015/09/pgbouncer-1-6-1/"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://github.com/pgbouncer/pgbouncer/issues/69"
      );
      # http://www.openwall.com/lists/oss-security/2015/09/04/3
      script_set_attribute(
        attribute:"see_also",
        value:"https://www.openwall.com/lists/oss-security/2015/09/04/3"
      );
      # https://vuxml.freebsd.org/freebsd/d76961da-56f6-11e5-934b-002590263bf5.html
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?81940f79"
      );
      script_set_attribute(attribute:"solution", value:"Update the affected package.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:pgbouncer");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2015/09/03");
      script_set_attribute(attribute:"patch_publication_date", value:"2015/09/09");
      script_set_attribute(attribute:"plugin_publication_date", value:"2015/09/10");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2015-2018 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"FreeBSD Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("freebsd_package.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    if (!get_kb_item("Host/FreeBSD/release")) audit(AUDIT_OS_NOT, "FreeBSD");
    if (!get_kb_item("Host/FreeBSD/pkg_info")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    
    if (pkg_test(save_report:TRUE, pkg:"pgbouncer=1.6.0")) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:pkg_report_get());
      else security_warning(0);
      exit(0);
    }
    else audit(AUDIT_HOST_NOT, "affected");
    
  • NASL familyGentoo Local Security Checks
    NASL idGENTOO_GLSA-201701-24.NASL
    descriptionThe remote host is affected by the vulnerability described in GLSA-201701-24 (PgBouncer: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in PgBouncer. Please review the CVE identifiers referenced below for details. Impact : A remote attacker might send a specially crafted package possibly resulting in a Denial of Service condition. Furthermore, a remote attacker might bypass authentication in configurations using the &ldquo;auth_user&rdquo; feature. Workaround : There is no known workaround at this time.
    last seen2020-06-01
    modified2020-06-02
    plugin id96418
    published2017-01-12
    reporterThis script is Copyright (C) 2017-2018 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/96418
    titleGLSA-201701-24 : PgBouncer: Multiple vulnerabilities
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were
    # extracted from Gentoo Linux Security Advisory GLSA 201701-24.
    #
    # The advisory text is Copyright (C) 2001-2018 Gentoo Foundation, Inc.
    # and licensed under the Creative Commons - Attribution / Share Alike 
    # license. See http://creativecommons.org/licenses/by-sa/3.0/
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(96418);
      script_version("$Revision: 3.4 $");
      script_cvs_date("$Date: 2018/01/26 17:15:57 $");
    
      script_cve_id("CVE-2015-4054", "CVE-2015-6817");
      script_xref(name:"GLSA", value:"201701-24");
    
      script_name(english:"GLSA-201701-24 : PgBouncer: Multiple vulnerabilities");
      script_summary(english:"Checks for updated package(s) in /var/db/pkg");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:
    "The remote Gentoo host is missing one or more security-related
    patches."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "The remote host is affected by the vulnerability described in GLSA-201701-24
    (PgBouncer: Multiple vulnerabilities)
    
        Multiple vulnerabilities have been discovered in PgBouncer. Please
          review the CVE identifiers referenced below for details.
      
    Impact :
    
        A remote attacker might send a specially crafted package possibly
          resulting in a Denial of Service condition. Furthermore, a remote
          attacker might bypass authentication in configurations using the
          &ldquo;auth_user&rdquo; feature.
      
    Workaround :
    
        There is no known workaround at this time."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://security.gentoo.org/glsa/201701-24"
      );
      script_set_attribute(
        attribute:"solution", 
        value:
    "All PgBouncer users should upgrade to the latest version:
          # emerge --sync
          # emerge --ask --oneshot --verbose '>=dev-db/pgbouncer-1.7.2'"
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:gentoo:linux:pgbouncer");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:gentoo:linux");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2017/01/11");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/01/12");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2017-2018 Tenable Network Security, Inc.");
      script_family(english:"Gentoo Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/Gentoo/release", "Host/Gentoo/qpkg-list");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("global_settings.inc");
    include("qpkg.inc");
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    if (!get_kb_item("Host/Gentoo/release")) audit(AUDIT_OS_NOT, "Gentoo");
    if (!get_kb_item("Host/Gentoo/qpkg-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    
    if (qpkg_check(package:"dev-db/pgbouncer", unaffected:make_list("ge 1.7.2"), vulnerable:make_list("lt 1.7.2"))) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:qpkg_report_get());
      else security_warning(0);
      exit(0);
    }
    else
    {
      tested = qpkg_tests_get();
      if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
      else audit(AUDIT_PACKAGE_NOT_INSTALLED, "PgBouncer");
    }