CVE-2015-7823 in Kentico
Summary
by MITRE
Open redirect vulnerability in CMSPages/GetDocLink.ashx in Kentico CMS 8.2 through 8.2.41 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL in the link parameter.
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Analysis
by VulDB Data Team • 06/19/2018
The vulnerability CVE-2015-7823 represents a critical open redirect flaw discovered in Kentico CMS versions 8.2 through 8.2.41 within the CMSPages/GetDocLink.ashx component. This vulnerability falls under the CWE-601 category of URL Redirection to Untrusted Site, which is classified as a security weakness that allows attackers to redirect users to malicious websites. The flaw specifically exists in the handling of URL parameters within the GetDocLink.ashx script, which processes document links within the content management system. The vulnerability enables remote attackers to manipulate the link parameter to redirect users to arbitrary web addresses, making it a significant vector for social engineering attacks.
The technical implementation of this vulnerability occurs when the CMS processes user-supplied URLs without proper validation or sanitization of the link parameter. Attackers can construct malicious URLs that exploit this weakness by including crafted redirect parameters that bypass the system's normal link validation mechanisms. The vulnerability specifically affects the document linking functionality within Kentico CMS, where the GetDocLink.ashx handler fails to properly validate or sanitize the input URL before processing it for redirection. This allows an attacker to inject malicious URLs that will be executed when users click on links within the CMS interface, particularly those that appear to be legitimate internal documents or resources.
The operational impact of this vulnerability is substantial as it enables sophisticated phishing attacks and social engineering campaigns that can compromise user trust and potentially steal credentials or sensitive information. When users are redirected to attacker-controlled websites through seemingly legitimate CMS links, they may unknowingly provide sensitive information or download malicious software. This vulnerability directly maps to the ATT&CK technique T1566.001 which involves phishing attacks through email or web interfaces, and can be leveraged in conjunction with other attack vectors to create comprehensive compromise scenarios. The open redirect vulnerability creates a trust exploitation opportunity where users are led to believe they are accessing legitimate internal resources while actually being redirected to external malicious sites.
Organizations running affected Kentico CMS versions should immediately implement mitigations including input validation and sanitization of all URL parameters, implementing strict URL validation routines that check against known good patterns, and deploying web application firewalls to filter malicious requests. The recommended approach involves modifying the GetDocLink.ashx handler to validate that redirect URLs conform to the expected domain or are explicitly whitelisted, ensuring that only trusted domains are allowed for redirection. Additionally, implementing proper logging and monitoring of redirect operations can help detect suspicious activities and potential exploitation attempts. Organizations should also consider implementing Content Security Policy headers and other browser-based protections to further mitigate the risk of exploitation. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for comprehensive security testing of all user-supplied data handling components within content management systems.