CVE-2015-3421 in eShop Plugin
Summary
by MITRE
The eshop_checkout function in checkout.php in the Wordpress Eshop plugin 6.3.11 and earlier does not validate variables in the "eshopcart" HTTP cookie, which allows remote attackers to perform cross-site scripting (XSS) attacks, or a path disclosure attack via crafted variables named after target PHP variables.
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Analysis
by VulDB Data Team • 06/19/2024
The vulnerability identified as CVE-2015-3421 affects the WordPress Eshop plugin version 6.3.11 and earlier, specifically within the eshop_checkout function located in checkout.php. This issue represents a critical security flaw that stems from inadequate input validation mechanisms within the plugin's cookie handling process. The vulnerability manifests when the plugin fails to properly sanitize or validate variables contained within the "eshopcart" HTTP cookie, creating an exploitable condition that can be leveraged by remote attackers to execute malicious code on affected systems.
The technical flaw in this vulnerability resides in the improper handling of user-supplied data through HTTP cookies, which directly violates established security principles for input validation and sanitization. When the eshop_checkout function processes the "eshopcart" cookie, it does not adequately validate or escape variables that may correspond to target PHP variables, allowing attackers to inject malicious payloads. This behavior creates a pathway for cross-site scripting attacks where attackers can execute arbitrary JavaScript code within the context of a victim's browser session, as well as path disclosure attacks that can reveal sensitive server path information. The vulnerability specifically aligns with CWE-79, which describes cross-site scripting flaws, and CWE-200, which addresses information exposure through path disclosure.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it provides attackers with multiple attack vectors that can compromise user sessions and potentially escalate to more severe security incidents. Remote attackers can exploit this vulnerability without requiring authentication, making it particularly dangerous in environments where WordPress sites are publicly accessible. The path disclosure component of the attack allows adversaries to gain knowledge of server file structures, which can be used to plan more sophisticated attacks against the underlying system. This vulnerability also aligns with ATT&CK technique T1059.007, which covers scripting through web shell execution, and T1068, which addresses exploit for privilege escalation.
Mitigation strategies for CVE-2015-3421 should prioritize immediate plugin updates to versions that address the input validation deficiencies in the checkout.php file. Administrators should also implement comprehensive cookie validation mechanisms that sanitize all user-supplied data before processing, particularly for variables that may correspond to PHP internal variables or system paths. Network-level protections such as web application firewalls can provide additional defense-in-depth measures by monitoring and blocking suspicious cookie content patterns. Regular security audits of WordPress plugins should include validation of cookie handling practices and input sanitization routines. Organizations should also consider implementing Content Security Policy headers to limit the execution of unauthorized scripts and reduce the impact of potential XSS exploitation. The vulnerability demonstrates the critical importance of proper input validation in web applications and serves as a reminder of the risks associated with legacy plugin versions that may not receive security updates.