CVE-2011-5082 in s2Member
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the s2Member Pro plugin before 111220 for WordPress allows remote attackers to inject arbitrary web script or HTML via the s2member_pro_authnet_checkout[coupon] parameter (aka Coupon Code field).
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Analysis
by VulDB Data Team • 04/13/2017
The CVE-2011-5082 vulnerability represents a critical cross-site scripting flaw discovered in the s2Member Pro WordPress plugin version 111220 and earlier. This vulnerability specifically targets the payment processing functionality of the plugin, creating a pathway for malicious actors to execute arbitrary web scripts within the context of authenticated user sessions. The vulnerability stems from inadequate input validation and output sanitization mechanisms within the plugin's handling of the Coupon Code field, which is part of the Authorize.net checkout process. The affected parameter s2member_pro_authnet_checkout[coupon] receives user input without proper sanitization, allowing attackers to inject malicious code that persists in the application's response.
This vulnerability operates under the CWE-79 classification as a classic cross-site scripting attack, where the malicious input is not properly escaped or filtered before being rendered back to users. The flaw enables attackers to exploit the trust relationship between the web application and its users, potentially allowing them to steal session cookies, deface websites, or redirect users to malicious sites. The s2Member Pro plugin's failure to implement proper input validation on the coupon parameter creates an attack surface that can be leveraged by remote threat actors without requiring authentication or privileged access to the WordPress installation. The vulnerability affects the core web application security model by allowing persistent XSS attacks that can compromise user sessions and potentially escalate to full system compromise.
The operational impact of CVE-2011-5082 extends beyond simple data theft, as it can enable attackers to manipulate the payment processing workflow and potentially intercept sensitive financial information. When users enter coupon codes during the Authorize.net checkout process, their input becomes vulnerable to injection attacks that can modify the checkout experience or redirect payments to attacker-controlled accounts. The vulnerability's remote exploitability means that attackers can target any website using the vulnerable plugin version without requiring physical access or local network presence, making it particularly dangerous in multi-tenant hosting environments. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1566.001 for initial access through malicious links and T1059.001 for command and control through script injection. The impact is amplified when considering that the s2Member Pro plugin typically handles user authentication and payment processing, making it a prime target for attackers seeking to compromise user accounts and financial data.
Mitigation strategies for CVE-2011-5082 must focus on immediate remediation through plugin updates to version 111220 or later, which contain the necessary input validation patches. Organizations should implement comprehensive input sanitization measures that escape or filter all user-supplied data before processing, particularly for fields that are rendered back to users in web responses. Network-level protections such as web application firewalls can provide additional defense-in-depth by monitoring for suspicious patterns in the coupon parameter values. Security monitoring should include detection of anomalous checkout behavior and unusual coupon code patterns that may indicate exploitation attempts. The vulnerability highlights the importance of regular security auditing of third-party plugins and maintaining up-to-date software versions to prevent exploitation of known vulnerabilities. Additionally, implementing proper content security policies and output encoding mechanisms can further reduce the risk of XSS exploitation, as these measures create multiple layers of protection against malicious script injection attacks.