CVE-2015-9345 in link-log Plugin
Summary
by MITRE
The link-log plugin before 2.0 for WordPress has HTTP Response Splitting.
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Analysis
by VulDB Data Team • 12/04/2023
The CVE-2015-9345 vulnerability represents a critical HTTP Response Splitting flaw discovered in the link-log plugin version 1.9 and earlier for the WordPress content management system. This vulnerability arises from inadequate input validation and sanitization within the plugin's handling of user-supplied data, specifically affecting how the plugin processes and outputs HTTP headers. The issue occurs when malicious actors can inject additional HTTP headers into responses generated by the plugin, potentially enabling various attack vectors including cache poisoning, cross-site scripting, and session hijacking. The vulnerability is particularly concerning as it affects a widely used WordPress plugin that many sites rely upon for link management and logging functionality, creating a significant attack surface for malicious actors targeting WordPress installations.
The technical implementation of this HTTP Response Splitting vulnerability stems from improper validation of user input within the plugin's codebase, where unfiltered data enters the HTTP response generation process. When the link-log plugin processes user-provided links or metadata, it fails to properly sanitize special characters that could be interpreted as HTTP header terminators, particularly the carriage return and line feed characters. This allows attackers to inject malicious headers into the HTTP response, effectively splitting the original response and injecting arbitrary content. The vulnerability is classified under CWE-113 as "Improper Neutralization of CRLF Sequences in HTTP Headers" and aligns with ATT&CK technique T1566.001 for "Phishing via Social Media" as attackers could leverage this to manipulate HTTP headers for malicious redirection or content injection. The flaw demonstrates a fundamental lack of input sanitization and output encoding practices that should be implemented in all web applications handling user data.
The operational impact of this vulnerability extends beyond simple data corruption or display issues, creating potential pathways for more severe security breaches within WordPress installations. Attackers could exploit this vulnerability to manipulate browser behavior through header injection, potentially redirecting users to malicious sites, injecting malicious JavaScript content, or even manipulating session cookies to hijack user sessions. The vulnerability's exploitation could lead to widespread compromise across multiple sites using the affected plugin version, as the flaw exists in the plugin's core functionality rather than requiring specific user interactions. Organizations running vulnerable WordPress installations face significant risk of data theft, service disruption, and reputational damage. The vulnerability's severity is amplified by the fact that many WordPress sites do not regularly update their plugins, leaving them exposed to known vulnerabilities for extended periods. Security researchers have noted that this type of vulnerability often serves as a stepping stone for more sophisticated attacks, as it provides attackers with the ability to manipulate HTTP responses and potentially gain further access to the underlying system.
Mitigation strategies for CVE-2015-9345 focus primarily on immediate plugin updates to version 2.0 or later, which contain the necessary fixes for input validation and header sanitization. System administrators should conduct comprehensive vulnerability assessments to identify all WordPress installations using the affected plugin version and prioritize immediate remediation. Additional protective measures include implementing proper input validation at multiple layers, including application-level filtering, web application firewalls, and network-level monitoring for suspicious HTTP header patterns. Organizations should also establish robust plugin management policies that include regular updates, security scanning, and monitoring for vulnerable components. The remediation process should involve thorough testing of the updated plugin to ensure compatibility with existing site functionality while maintaining security posture. Security teams should implement logging and monitoring for HTTP header injection attempts and establish incident response procedures for potential exploitation of similar vulnerabilities. The vulnerability underscores the importance of maintaining up-to-date third-party components and implementing defense-in-depth strategies to protect against HTTP response splitting attacks that could compromise entire web applications.