CVE-2015-9240 in Keystone Module
Summary
by MITRE
Due to a bug in the the default sign in functionality in the keystone node module before 0.3.16, incomplete email addresses could be matched. A correct password is still required to complete sign in.
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Analysis
by VulDB Data Team • 02/09/2020
The vulnerability identified as CVE-2015-9240 affects the keystone node module, a popular web application framework for node.js that provides administrative interfaces and content management capabilities. This security flaw resides in the default sign in functionality of keystone versions prior to 0.3.16, creating a potential authentication bypass vector that could be exploited by malicious actors. The issue specifically involves a flaw in how the system handles email address validation during the authentication process, allowing for incomplete email addresses to be matched against user records. This vulnerability represents a significant concern for applications relying on keystone for their administrative interfaces, as it could potentially enable unauthorized access to sensitive systems. The vulnerability is categorized under CWE-287 which addresses improper authentication issues, and aligns with ATT&CK technique T1110.003 for credential access through brute force or password guessing attacks. The flaw demonstrates a classic case of insufficient input validation where the system fails to properly verify the completeness and validity of email addresses before attempting authentication matching.
The technical implementation of this vulnerability stems from the way keystone processes email addresses during the sign in procedure. When users attempt to log in, the system performs a lookup based on the provided email address to locate the corresponding user account. However, due to the bug in the authentication logic, the system accepts partial email addresses or malformed email formats that should normally be rejected during validation. This incomplete matching process allows an attacker to potentially exploit the system by using truncated email addresses or email formats that match partial user records. The authentication mechanism still requires a valid password to complete the login process, but the initial email matching step becomes vulnerable to manipulation. The vulnerability essentially creates a window where attackers can bypass the standard email validation checks, potentially leading to account enumeration or session hijacking scenarios. This flaw demonstrates poor input sanitization practices and highlights the importance of robust email address validation in authentication systems.
The operational impact of CVE-2015-9240 extends beyond simple authentication bypass scenarios and could enable more sophisticated attack vectors within affected systems. Organizations using keystone versions before 0.3.16 face potential risks including unauthorized access to administrative interfaces, data breaches through session manipulation, and possible account takeover attacks. The vulnerability could be particularly dangerous in environments where administrative access provides access to sensitive databases, user management systems, or critical business applications. Attackers might leverage this flaw to perform account enumeration by testing various email address formats to identify valid user accounts, which could then be targeted through password spraying or brute force attacks. The fact that a correct password is still required for final authentication provides some mitigation but does not eliminate the risk entirely, as the initial email matching step could still provide attackers with information about valid user accounts. This vulnerability affects the principle of least privilege by potentially allowing unauthorized access to systems that should only be accessible to authenticated administrators.
Mitigation strategies for CVE-2015-9240 primarily focus on upgrading to keystone version 0.3.16 or later, which contains the necessary fixes to address the incomplete email matching logic. Organizations should immediately implement this upgrade across all affected systems and verify that the authentication process properly validates complete email addresses before attempting user lookups. Additional defensive measures include implementing rate limiting on authentication attempts to prevent automated enumeration attacks, configuring proper logging to detect suspicious authentication patterns, and ensuring that email validation is performed consistently throughout the application. Security teams should also conduct thorough audits of all authentication mechanisms to identify similar vulnerabilities in custom implementations or other third-party modules. The fix implemented in keystone 0.3.16 addresses the core issue by enforcing stricter email address validation and ensuring that only complete, properly formatted email addresses are accepted during the sign in process. Organizations should also consider implementing multi-factor authentication as an additional layer of security to protect against potential exploitation of similar vulnerabilities. Regular security assessments and dependency updates should be part of ongoing security practices to prevent similar issues from arising in the future, particularly given the ATT&CK framework's emphasis on credential access techniques and the importance of maintaining up-to-date software components to prevent exploitation of known vulnerabilities.