CVE-2015-9372 in Membership Add-on for iThemes Exchange
Summary
by MITRE
Membership Add-on for iThemes Exchange before 1.3.0 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-2015-9372 affects the Membership Add-on for iThemes Exchange plugin version prior to 1.3.0 within the WordPress ecosystem. This represents a cross-site scripting vulnerability that specifically targets the plugin's handling of URL query parameters through the add_query_arg() and remove_query_arg() WordPress functions. The flaw exists in the plugin's user input validation and output sanitization mechanisms, creating an avenue for malicious actors to inject arbitrary JavaScript code into the application's response. The vulnerability is particularly concerning as it operates within a widely used e-commerce plugin that integrates with WordPress, potentially affecting thousands of websites that rely on this functionality for membership management and user access control.
The technical exploitation of this vulnerability occurs when the plugin processes user-supplied input through the WordPress query argument handling functions without adequate sanitization or output encoding. When a user visits a page that utilizes these functions with unfiltered input, the malicious payload can be executed within the context of another user's browser session. The add_query_arg() and remove_query_arg() functions are designed to manipulate URL query strings, but in this case, they fail to properly sanitize the input parameters before incorporating them into the HTML response. This creates a classic XSS vector where attackers can inject malicious scripts that execute in the victim's browser, potentially stealing session cookies, performing unauthorized actions, or redirecting users to malicious sites. The vulnerability is categorized under CWE-79 as Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly sanitize user input before it is rendered in web pages.
The operational impact of CVE-2015-9372 extends beyond simple script execution as it can enable attackers to compromise user sessions and potentially gain elevated privileges within the affected WordPress environment. Attackers could leverage this vulnerability to execute malicious scripts that steal authentication tokens, modify user permissions, or redirect users to phishing sites. The vulnerability is particularly dangerous in the context of membership-based systems where users may have elevated privileges or access to sensitive data. When combined with other attack vectors, this XSS flaw could provide attackers with a foothold to escalate privileges within the WordPress installation, potentially leading to complete system compromise. The attack requires minimal sophistication and can be automated, making it attractive to threat actors seeking to exploit vulnerable WordPress installations at scale.
Mitigation strategies for this vulnerability should include immediate patching of the iThemes Exchange Membership Add-on to version 1.3.0 or later, which contains the necessary input sanitization fixes. Organizations should also implement proper output encoding for all dynamic content generated from user inputs, particularly when using WordPress functions that manipulate query arguments. The implementation of Content Security Policy headers can provide additional defense-in-depth by restricting the sources from which scripts can be loaded and executed. Security monitoring should be enhanced to detect suspicious query parameter patterns that might indicate exploitation attempts. Additionally, the principle of least privilege should be enforced by ensuring that membership plugin functionality operates with minimal required permissions and that user inputs are thoroughly validated before processing. This vulnerability demonstrates the importance of proper input validation and output encoding practices, aligning with ATT&CK technique T1203 for Exploitation for Credential Access and T1566 for Phishing, as attackers could leverage this vector to obtain user credentials or redirect users to malicious content.