Vulnerabilities > CVE-2019-5420 - Use of Insufficiently Random Values vulnerability in multiple products
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH network
low complexity
rubyonrails
debian
fedoraproject
CWE-330
critical
nessus
exploit available
metasploit
Summary
A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow an attacker to guess the automatically generated development mode secret token. This secret token can be used in combination with other Rails internals to escalate to a remote code execution exploit.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Brute Force In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset. Examples of secrets can include, but are not limited to, passwords, encryption keys, database lookup keys, and initial values to one-way functions. The key factor in this attack is the attackers' ability to explore the possible secret space rapidly. This, in turn, is a function of the size of the secret space and the computational power the attacker is able to bring to bear on the problem. If the attacker has modest resources and the secret space is large, the challenge facing the attacker is intractable. While the defender cannot control the resources available to an attacker, they can control the size of the secret space. Creating a large secret space involves selecting one's secret from as large a field of equally likely alternative secrets as possible and ensuring that an attacker is unable to reduce the size of this field using available clues or cryptanalysis. Doing this is more difficult than it sounds since elimination of patterns (which, in turn, would provide an attacker clues that would help them reduce the space of potential secrets) is difficult to do using deterministic machines, such as computers. Assuming a finite secret space, a brute force attack will eventually succeed. The defender must rely on making sure that the time and resources necessary to do so will exceed the value of the information. For example, a secret space that will likely take hundreds of years to explore is likely safe from raw-brute force attacks.
- Signature Spoofing by Key Recreation An attacker obtains an authoritative or reputable signer's private signature key by exploiting a cryptographic weakness in the signature algorithm or pseudorandom number generation and then uses this key to forge signatures from the original signer to mislead a victim into performing actions that benefit the attacker.
- Session Credential Falsification through Prediction This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.
Exploit-Db
| file | exploits/linux/remote/46785.rb |
| id | EDB-ID:46785 |
| last seen | 2019-05-02 |
| modified | 2019-05-02 |
| platform | linux |
| port | 3000 |
| published | 2019-05-02 |
| reporter | Exploit-DB |
| source | https://www.exploit-db.com/download/46785 |
| title | Ruby On Rails - DoubleTap Development Mode secret_key_base Remote Code Execution (Metasploit) |
| type | remote |
Metasploit
| description | This module exploits a vulnerability in Ruby on Rails. In development mode, a Rails application would use its name as the secret_key_base, and can be easily extracted by visiting an invalid resource for a path. As a result, this allows a remote user to create and deliver a signed serialized payload, load it by the application, and gain remote code execution. |
| id | MSF:EXPLOIT/MULTI/HTTP/RAILS_DOUBLE_TAP |
| last seen | 2020-06-14 |
| modified | 2019-06-20 |
| published | 2019-04-25 |
| references |
|
| reporter | Rapid7 |
| source | https://github.com/rapid7/metasploit-framework/blob/master//modules/exploits/multi/http/rails_double_tap.rb |
| title | Ruby On Rails DoubleTap Development Mode secret_key_base Vulnerability |
Nessus
| NASL family | Fedora Local Security Checks |
| NASL id | FEDORA_2019-1CFE24DB5C.NASL |
| description | Update Ruby on Rails to 5.2.3. Fixes CVE-2019-5418 CVE-2019-5419 CVE-2019-5420. 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. |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 124724 |
| published | 2019-05-10 |
| 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/124724 |
| title | Fedora 30 : 1:rubygem-actionmailer / 1:rubygem-actionpack / etc (2019-1cfe24db5c) |
| code | |
Packetstorm
| data source | https://packetstormsecurity.com/files/download/152704/rails_double_tap.rb.txt |
| id | PACKETSTORM:152704 |
| last seen | 2019-05-02 |
| published | 2019-05-01 |
| reporter | sinn3r |
| source | https://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.html |
| title | Ruby On Rails DoubleTap Development Mode secret_key_base Remote Code Execution |
References
- https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/
- http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.html
- https://www.exploit-db.com/exploits/46785/
- https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/