Vulnerabilities > CVE-2018-12551 - Improper Authentication vulnerability in Eclipse Mosquitto
Summary
When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use a password file for authentication, any malformed data in the password file will be treated as valid. This typically means that the malformed data becomes a username and no password. If this occurs, clients can circumvent authentication and get access to the broker by using the malformed username. In particular, a blank line will be treated as a valid empty username. Other security measures are unaffected. Users who have only used the mosquitto_passwd utility to create and modify their password files are unaffected by this vulnerability.
Vulnerable Configurations
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 family Fedora Local Security Checks NASL id FEDORA_2019-8CBE2A05CD.NASL description Fixes for the following CVES : - CVE-2018-12546 - CVE-2018-12550 - CVE-2018-12551 The list of other fixes addressed in version 1.5.6 is: Broker : - Fixed comment handling for config options that have optional arguments. - Improved documentation around bridge topic remapping. - Handle mismatched handshakes (e.g. QoS1 PUBLISH with QoS2 reply) properly. - Fix spaces not being allowed in the bridge remote_username option. Closes #1131. - Allow broker to always restart on Windows when using log_dest file. Closes #1080. - Fix Will not being sent for Websockets clients. Closes #1143. - Windows: Fix possible crash when client disconnects. Closes #1137. - Fixed durable clients being unable to receive messages when offline, when per_listener_settings was set to true. Closes #1081. - Add log message for the case where a client is disconnected for sending a topic with invalid UTF-8. Closes #1144. Library : - Fix TLS connections not working over SOCKS. - Don last seen 2020-06-01 modified 2020-06-02 plugin id 122285 published 2019-02-19 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/122285 title Fedora 28 : mosquitto (2019-8cbe2a05cd) code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Fedora Security Advisory FEDORA-2019-8cbe2a05cd. # include("compat.inc"); if (description) { script_id(122285); script_version("1.4"); script_cvs_date("Date: 2020/02/12"); script_cve_id("CVE-2018-12546", "CVE-2018-12550", "CVE-2018-12551"); script_xref(name:"FEDORA", value:"2019-8cbe2a05cd"); script_name(english:"Fedora 28 : mosquitto (2019-8cbe2a05cd)"); script_summary(english:"Checks rpm output for the updated package."); script_set_attribute( attribute:"synopsis", value:"The remote Fedora host is missing a security update." ); script_set_attribute( attribute:"description", value: "Fixes for the following CVES : - CVE-2018-12546 - CVE-2018-12550 - CVE-2018-12551 The list of other fixes addressed in version 1.5.6 is: Broker : - Fixed comment handling for config options that have optional arguments. - Improved documentation around bridge topic remapping. - Handle mismatched handshakes (e.g. QoS1 PUBLISH with QoS2 reply) properly. - Fix spaces not being allowed in the bridge remote_username option. Closes #1131. - Allow broker to always restart on Windows when using log_dest file. Closes #1080. - Fix Will not being sent for Websockets clients. Closes #1143. - Windows: Fix possible crash when client disconnects. Closes #1137. - Fixed durable clients being unable to receive messages when offline, when per_listener_settings was set to true. Closes #1081. - Add log message for the case where a client is disconnected for sending a topic with invalid UTF-8. Closes #1144. Library : - Fix TLS connections not working over SOCKS. - Don't clear SSL context when TLS connection is closed, meaning if a user provided an external SSL_CTX they have less chance of leaking references. Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. 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://bodhi.fedoraproject.org/updates/FEDORA-2019-8cbe2a05cd" ); script_set_attribute( attribute:"solution", value:"Update the affected mosquitto package." ); 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:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:mosquitto"); script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:28"); script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/27"); script_set_attribute(attribute:"patch_publication_date", value:"2019/02/18"); script_set_attribute(attribute:"plugin_publication_date", value:"2019/02/19"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof."); script_family(english:"Fedora Local Security Checks"); script_dependencies("ssh_get_info.nasl"); script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/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/RedHat/release"); if (isnull(release) || "Fedora" >!< release) audit(AUDIT_OS_NOT, "Fedora"); os_ver = pregmatch(pattern: "Fedora.*release ([0-9]+)", string:release); if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Fedora"); os_ver = os_ver[1]; if (! preg(pattern:"^28([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 28", "Fedora " + os_ver); if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu); flag = 0; if (rpm_check(release:"FC28", reference:"mosquitto-1.5.6-1.fc28")) flag++; if (flag) { security_report_v4( port : 0, severity : SECURITY_WARNING, 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, "mosquitto"); }
NASL family Debian Local Security Checks NASL id DEBIAN_DSA-4388.NASL description Three vulnerabilities were discovered in the Mosquitto MQTT broker, which could result in authentication bypass. Please refer to https://mosquitto.org/blog/2019/02/version-1-5-6-released/ for additional information. last seen 2020-06-01 modified 2020-06-02 plugin id 122069 published 2019-02-11 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/122069 title Debian DSA-4388-1 : mosquitto - security update NASL family SuSE Local Security Checks NASL id OPENSUSE-2019-233.NASL description This update for mosquitto fixes the following issues : Security issues fixed : - CVE-2018-12546: Fixed an issue with revoked access to topics (bsc#1125019). - CVE-2018-12551: Fixed an issue which allowed malformed data in the password file to be treated as valid (bsc#1125020). - CVE-2018-12550: Fixed an an issue which treats an empty ACL file wrongly (bsc#1125021). last seen 2020-06-01 modified 2020-06-02 plugin id 122417 published 2019-02-25 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/122417 title openSUSE Security Update : mosquitto (openSUSE-2019-233) NASL family Debian Local Security Checks NASL id DEBIAN_DLA-1972.NASL description Several issues have been found in mosquitto, a MQTT version 3.1/3.1.1 compatible message broker. CVE-2017-7655 A Null dereference vulnerability in the Mosquitto library could lead to crashes for those applications using the library. CVE-2018-12550 An ACL file with no statements was treated as having a default allow policy. The new behaviour of an empty ACL file is a default policy of access denied. (this is in compliance with all newer releases) CVE-2018-12551 Malformed authentication data in the password file could allow clients to circumvent authentication and get access to the broker. CVE-2019-11779 Fix for processing a crafted SUBSCRIBE packet containing a topic that consists of approximately 65400 or more last seen 2020-06-01 modified 2020-06-02 plugin id 130285 published 2019-10-28 reporter This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/130285 title Debian DLA-1972-1 : mosquitto security update