CVE-2019-5420 in Ruby on Rails
Summary
by MITRE
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.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability identified as CVE-2019-5420 represents a critical remote code execution flaw affecting Ruby on Rails applications running in development mode. This weakness specifically impacts versions prior to 5.2.2.1 and 6.0.0.beta3, where the framework generates predictable secret tokens that can be exploited by malicious actors. The vulnerability stems from insufficient randomness in the secret token generation process, creating a pathway for attackers to compromise application security through predictable cryptographic values. According to CWE-330, this issue falls under the category of using insecurely generated random numbers, which directly enables attackers to bypass authentication mechanisms and gain unauthorized access to application internals.
The technical exploitation of this vulnerability begins with an attacker's ability to guess the development mode secret token through brute force or pattern analysis techniques. Once obtained, this token serves as a foothold that allows attackers to interact with Rails internal components that should normally be protected from external access. The secret token's predictability enables malicious users to manipulate Rails' internal mechanisms, particularly those related to session management and request processing. This exploitation pathway aligns with ATT&CK technique T1210, which describes the use of exploitation for privilege escalation through predictable tokens and credentials. The vulnerability's impact extends beyond simple authentication bypass as it provides attackers with access to critical application internals that can be leveraged for further compromise.
The operational impact of CVE-2019-5420 is severe and far-reaching for organizations running affected Rails applications in development environments. Attackers who successfully exploit this vulnerability can execute arbitrary code on the application server, potentially leading to complete system compromise. The development mode nature of the vulnerability means that applications configured for development environments are particularly at risk, as these environments often contain additional debugging features and less restrictive security controls. Organizations may face data breaches, system infiltration, and potential lateral movement within their network infrastructure. The vulnerability's exploitation requires minimal sophistication, making it attractive to attackers who seek automated exploitation methods. Security teams must consider that this vulnerability can be exploited remotely without requiring user interaction or additional authentication, creating a high-severity threat that can affect applications in production environments if development mode configurations are improperly deployed.
Mitigation strategies for CVE-2019-5420 primarily focus on upgrading to patched versions of Ruby on Rails where the secret token generation has been improved to use cryptographically secure random number generators. Organizations should immediately update their Rails applications to versions 5.2.2.1 or 6.0.0.beta3 and later, which address the predictable token generation issue. Additionally, administrators should ensure that development mode is not enabled in production environments, as this vulnerability specifically targets development configurations. Security configurations should enforce strict access controls and network segmentation to limit exposure of development environments to external threats. The implementation of proper monitoring and logging mechanisms can help detect exploitation attempts, while regular security audits should verify that applications are not running in insecure development modes. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation patterns associated with this vulnerability.