Vulnerabilities > CVE-2018-12546 - Incorrect Permission Assignment for Critical Resource vulnerability in Eclipse Mosquitto
Attack vector
NETWORK Attack complexity
LOW Privileges required
LOW Confidentiality impact
NONE Integrity impact
HIGH Availability impact
NONE Summary
In Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) when a client publishes a retained message to a topic, then has its access to that topic revoked, the retained message will still be published to clients that subscribe to that topic in the future. In some applications this may result in clients being able cause effects that would otherwise not be allowed.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Accessing Functionality Not Properly Constrained by ACLs In applications, particularly web applications, access to functionality is mitigated by the authorization framework, whose job it is to map ACLs to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application or can run queries for data that he is otherwise not supposed to.
- Privilege Abuse An adversary is able to exploit features of the target that should be reserved for privileged users or administrators but are exposed to use by lower or non-privileged accounts. Access to sensitive information and functionality must be controlled to ensure that only authorized users are able to access these resources. If access control mechanisms are absent or misconfigured, a user may be able to access resources that are intended only for higher level users. An adversary may be able to exploit this to utilize a less trusted account to gain information and perform activities reserved for more trusted accounts. This attack differs from privilege escalation and other privilege stealing attacks in that the adversary never actually escalates their privileges but instead is able to use a lesser degree of privilege to access resources that should be (but are not) reserved for higher privilege accounts. Likewise, the adversary does not exploit trust or subvert systems - all control functionality is working as configured but the configuration does not adequately protect sensitive resources at an appropriate level.
- Directory Indexing An adversary crafts a request to a target that results in the target listing/indexing the content of a directory as output. One common method of triggering directory contents as output is to construct a request containing a path that terminates in a directory name rather than a file name since many applications are configured to provide a list of the directory's contents when such a request is received. An adversary can use this to explore the directory tree on a target as well as learn the names of files. This can often end up revealing test files, backup files, temporary files, hidden files, configuration files, user accounts, script contents, as well as naming conventions, all of which can be used by an attacker to mount additional attacks.
- Accessing, Modifying or Executing Executable Files An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
- Exploiting Incorrectly Configured Access Control Security Levels An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack. Most commonly, attackers would take advantage of controls that provided too little protection for sensitive activities in order to perform actions that should be denied to them. In some circumstances, an attacker may be able to take advantage of overly restrictive access control policies, initiating denial of services (if an application locks because it unexpectedly failed to be granted access) or causing other legitimate actions to fail due to security. The latter class of attacks, however, is usually less severe and easier to detect than attacks based on inadequate security restrictions. This attack pattern differs from CAPEC 1, "Accessing Functionality Not Properly Constrained by ACLs" in that the latter describes attacks where sensitive functionality lacks access controls, where, in this pattern, the access control is present, but incorrectly configured.
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)