CVE-2015-9373 in PayPal Pro Add-on for iThemes Exchange
Summary
by MITRE
PayPal Pro Add-on for iThemes Exchange before 1.1.0 for WordPress has XSS via add_query_arg() and remove_query_arg().
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2015-9373 affects the PayPal Pro Add-on for iThemes Exchange version prior to 1.1.0 within the WordPress ecosystem. This security flaw resides in the handling of URL query parameters through the WordPress functions add_query_arg() and remove_query_arg() which are commonly used for constructing and manipulating URLs in web applications. The issue manifests as a cross-site scripting vulnerability that could potentially allow attackers to inject malicious scripts into web pages viewed by other users. The vulnerability specifically impacts the iThemes Exchange platform which is a popular e-commerce solution for WordPress sites, making it a target for attackers seeking to exploit web application flaws in online payment processing systems.
The technical implementation of this vulnerability stems from inadequate input sanitization and output escaping within the PayPal Pro Add-on's handling of query parameters. When the add_query_arg() and remove_query_arg() functions process user-supplied data, they fail to properly validate or escape the input before incorporating it into the HTML output. This creates an environment where malicious actors can craft specially formatted URLs containing script payloads that get executed in the context of other users' browsers when they visit pages that utilize these functions. The vulnerability is particularly concerning because it operates at the web application layer where user interactions with payment processing systems occur, potentially allowing attackers to steal session cookies, perform unauthorized transactions, or redirect users to malicious sites.
The operational impact of this vulnerability extends beyond simple script injection as it specifically targets e-commerce functionality within WordPress environments. Attackers could exploit this flaw to manipulate payment flows, redirect users to fraudulent payment pages, or extract sensitive information from user sessions. The vulnerability affects not just individual users but could compromise entire e-commerce operations by undermining user trust and potentially enabling financial fraud. Given that iThemes Exchange is designed for business use cases involving financial transactions, the implications are severe as attackers could target merchant sites to gain access to payment information or disrupt commerce operations. This type of vulnerability also represents a significant risk to the broader WordPress ecosystem as it demonstrates how third-party plugins can introduce security weaknesses that affect the entire platform's security posture.
Organizations should implement immediate mitigations including updating to the patched version 1.1.0 or later of the PayPal Pro Add-on for iThemes Exchange. The fix should involve proper input validation and output escaping of query parameters before they are processed by add_query_arg() and remove_query_arg() functions. Security measures should include implementing content security policies to prevent unauthorized script execution, conducting regular security audits of WordPress plugins, and establishing monitoring for suspicious URL parameter patterns. This vulnerability aligns with CWE-79 - Cross-site Scripting and maps to ATT&CK technique T1212 - Exploitation for Credential Access, as it could potentially lead to session hijacking and credential theft. Organizations should also consider implementing web application firewalls to detect and block malicious query parameter patterns and maintain comprehensive logging of URL access patterns for security monitoring purposes. The vulnerability demonstrates the critical importance of securing all components within web application ecosystems, particularly those handling financial transactions, as even minor flaws in third-party plugins can have significant security implications for entire platforms.