CVE-2015-1855 in Ruby
Summary
by MITRE
verify_certificate_identity in the OpenSSL extension in Ruby before 2.0.0 patchlevel 645, 2.1.x before 2.1.6, and 2.2.x before 2.2.2 does not properly validate hostnames, which allows remote attackers to spoof servers via vectors related to (1) multiple wildcards, (1) wildcards in IDNA names, (3) case sensitivity, and (4) non-ASCII characters.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2015-1855 represents a critical flaw in the OpenSSL extension implementation within Ruby programming language versions prior to specific patch levels. This weakness resides in the verify_certificate_identity function which is responsible for validating SSL/TLS certificate hostnames during secure communications. The flaw enables attackers to bypass hostname validation mechanisms through several specific vectors that exploit the improper handling of certificate verification logic.
The technical implementation of this vulnerability stems from insufficient validation of hostname patterns within SSL certificates, particularly when dealing with wildcard certificates and internationalized domain names. Attackers can exploit multiple aspects of this flaw including scenarios with multiple wildcards in certificate subject alternative names, wildcards present in internationalized domain names using IDNA (Internationalizing Domain Names in Applications) encoding, case sensitivity variations in hostname matching, and handling of non-ASCII character sequences. These specific vectors demonstrate a fundamental weakness in the certificate validation algorithm that fails to properly enforce strict hostname matching rules.
The operational impact of this vulnerability is significant as it allows remote attackers to perform man-in-the-middle attacks against Ruby applications that rely on SSL/TLS certificate validation for security. An attacker could present a malicious certificate that appears to be from a legitimate server due to the improper validation logic, potentially leading to data interception, session hijacking, or unauthorized access to sensitive information. This vulnerability affects a wide range of Ruby applications including web servers, API clients, and any software that establishes secure connections using the OpenSSL extension.
The flaw aligns with CWE-295 which specifically addresses improper certificate validation and relates to the broader category of certificate and public key validation issues. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access through network protocol manipulation and privilege escalation via trusted connection establishment. Organizations using affected Ruby versions face substantial risk as the vulnerability can be exploited without requiring special privileges or user interaction, making it particularly dangerous for web applications and services that handle sensitive data.
Mitigation strategies include immediate upgrading to patched versions of Ruby including 2.0.0 patchlevel 645, 2.1.x version 2.1.6, and 2.2.x version 2.2.2 or later. System administrators should also consider implementing additional monitoring for suspicious certificate validation events and network traffic anomalies. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected Ruby versions and ensure proper patch management processes are in place to prevent similar issues in the future. The vulnerability demonstrates the critical importance of maintaining up-to-date cryptographic libraries and proper certificate validation practices in secure application development.