CVE-2013-4339 in WordPress
Summary
by MITRE
WordPress before 3.6.1 does not properly validate URLs before use in an HTTP redirect, which allows remote attackers to bypass intended redirection restrictions via a crafted string.
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Analysis
by VulDB Data Team • 05/24/2021
WordPress versions prior to 3.6.1 contained a critical validation flaw in their URL handling mechanism that enabled remote attackers to exploit HTTP redirect functionality for unauthorized access. This vulnerability specifically affected the wp_redirect function which failed to properly sanitize and validate URL inputs before executing redirection operations. The flaw allowed malicious actors to craft specially formatted strings that could bypass intended security restrictions and redirect users to arbitrary destinations, potentially leading to phishing attacks or malicious payload delivery.
The technical implementation of this vulnerability stems from insufficient input validation within WordPress core redirect functionality. When WordPress processes redirect requests, it accepts user-provided URLs without adequate sanitization, allowing attackers to inject malicious protocols or manipulate the redirect target. This weakness is particularly dangerous because it operates at the application layer and can be exploited through various attack vectors including malicious comments, contact forms, or crafted URLs in HTTP requests. The vulnerability enables what is known as open redirect attacks where an attacker can force a legitimate website to redirect users to malicious sites, potentially bypassing security controls such as URL filtering or content security policies.
The operational impact of CVE-2013-4339 extends beyond simple redirection manipulation and represents a significant threat to user security and website integrity. Attackers could leverage this vulnerability to create convincing phishing campaigns by redirecting users to fraudulent login pages that appear legitimate, or to deliver malware through malicious redirects. The vulnerability affects all WordPress installations running versions earlier than 3.6.1, making it particularly widespread and dangerous for websites that failed to keep their core software updated. This flaw directly aligns with CWE-601 Open Redirect vulnerability classification, which specifically addresses situations where web applications fail to properly validate redirect URLs.
The exploitation of this vulnerability demonstrates a clear pathway for threat actors to perform social engineering attacks while maintaining the appearance of legitimate website behavior. The attack surface is extensive since many WordPress installations use various user input mechanisms that can trigger the vulnerable redirect functionality. Organizations and website administrators who failed to patch this vulnerability were left exposed to potential data theft, credential harvesting, and reputation damage. This vulnerability also maps to several ATT&CK techniques including T1566 Phishing and T1071.004 Application Layer Protocol HTTP, highlighting its potential for both initial access and lateral movement within compromised networks.
Mitigation strategies for CVE-2013-4339 require immediate patching of WordPress installations to version 3.6.1 or later, which implements proper URL validation and sanitization. Additionally, administrators should implement comprehensive monitoring for suspicious redirect patterns and consider implementing additional security layers such as content security policies that restrict redirect behavior. The vulnerability underscores the importance of regular security updates and proper input validation practices within web applications, as demonstrated by the remediation measures that were implemented in the patched versions of WordPress. Organizations should also conduct thorough security assessments of their web applications to identify similar validation flaws that could present analogous security risks.