This vulnerability allows users to manipulate the session return URL, leading to potential open redirection. Specifically, if a user can set the value of session[:return_to] to a URL with multiple leading slashes (e.g., /////example.com), they can be redirected to an external domain (http://example.com). This represents a significant risk, as it could facilitate phishing attacks.
The vulnerability has a CVSS score of 7.6, indicating high severity. The attack vector is network-based, and the attack complexity is low, making this vulnerability particularly concerning for organizations. User interaction is required, which may limit the attack surface but does not mitigate the risk.
Organizations should prioritize patching immediately to mitigate this vulnerability. The affected versions of the clearance package are those prior to 2.5.0. If not addressed, the risk to organizations includes potential unauthorized access through redirection to malicious sites.
No public exploit or proof of concept has been confirmed for this vulnerability, but given its nature, it remains essential for organizations to take proactive measures in addressing it.
Vulnerability Details
The vulnerability affects the thoughtbot clearance package versions earlier than 2.5.0. The CVSS scores vary based on different assessments, with the primary source reporting a base score of 7.6, classifying it as high severity. The CWE classification is CWE-601, indicating the nature of the vulnerability as an open redirect.
Technical Analysis
The root cause of this vulnerability lies in the improper handling of user input for the session return URL. Specifically, the application fails to validate or sanitize the user-provided URL, allowing for multiple leading slashes, which can redirect users to unintended external sites, thereby compromising security.
The attack vector is network-based, with low complexity, meaning attackers can exploit this vulnerability with minimal effort. No privileges are required to exploit this vulnerability, but user interaction is necessary to trigger the attack.
The confidentiality impact is low, as the attacker may not gain direct access to sensitive information, but the integrity impact is also low. However, the availability impact is high, as users can be redirected away from intended content, leading to potential phishing scenarios.
Risk & Impact Analysis
Real-world deployment of this vulnerability poses significant risk to organizations. The potential for redirection to malicious sites can lead to credential theft and unauthorized access. The urgency for organizations is classified as high, given the CVSS score of 7.6 and the lack of any known mitigations or workarounds. Organizations must assess their exposure and take immediate action to patch affected systems.
The blast radius potential is considerable, especially for organizations relying heavily on the clearance package for user authentication and session management. Any vulnerability in such critical components can have cascading effects across the application and its users.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of the clearance package are all versions prior to 2.5.0. Organizations using these versions must upgrade to the latest release to mitigate this vulnerability.
Mitigation & Remediation
To remediate this vulnerability, organizations should update the clearance package to version 2.5.0 or later. If an immediate upgrade is not feasible, organizations should consider implementing input validation on the session return URL to prevent multiple leading slashes and external redirects.
Additionally, organizations can enhance their security posture by instituting proper monitoring for unusual URL patterns and implementing network controls to restrict access to known malicious domains.
Continuous security testing can also help identify similar vulnerabilities in the application.
Detection Guidance
Organizations should monitor logs for unusual redirects and any unexpected changes in session behavior. Behavioral anomalies related to user sessions should be investigated promptly to prevent potential exploitation.
Network signatures for known malicious domains can also assist in detecting attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of input validation and proper session management in web applications. As attackers increasingly leverage such vulnerabilities for exploitation, organizations must prioritize secure coding practices.
Security teams should regularly review their applications for similar weaknesses and consider adopting a comprehensive vulnerability management program to mitigate risks associated with vulnerabilities like CVE-2021-23435.
Furthermore, organizations should stay informed about emerging threats and vulnerabilities by following trusted sources and incorporating penetration testing methodologies into their security strategies.
Engaging in proactive security measures, such as regular security assessments and audits, will help organizations defend against similar vulnerabilities in the future.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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