CVE-2017-6213 in invoice-sdk-php
Summary
by MITRE
paypal/invoice-sdk-php is vulnerable to reflected XSS in samples/permissions.php via the permToken parameter, resulting in code execution.
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Analysis
by VulDB Data Team • 04/29/2023
The vulnerability identified as CVE-2017-6213 affects the paypal/invoice-sdk-php library, specifically targeting the samples/permissions.php file through improper input validation mechanisms. This reflected cross-site scripting vulnerability arises when the permToken parameter is not adequately sanitized before being rendered in the application's response, creating a pathway for malicious actors to inject arbitrary JavaScript code. The flaw resides in the library's failure to implement proper output encoding or input validation controls, allowing attackers to craft malicious payloads that execute within the context of other users' browsers.
The technical implementation of this vulnerability demonstrates a classic reflected XSS pattern where user-supplied input flows directly into the HTTP response without appropriate sanitization. When the permToken parameter is passed to the permissions.php script, the application fails to validate or escape the input before incorporating it into HTML output. This creates an environment where an attacker can craft a URL containing malicious JavaScript code within the permToken parameter, which when visited by a victim, gets executed in their browser session. The vulnerability is particularly concerning as it operates entirely within the web application layer, requiring no special privileges or access to system resources beyond standard web browsing capabilities.
The operational impact of this vulnerability extends beyond simple script execution, as reflected XSS attacks can lead to session hijacking, credential theft, and unauthorized transactions within the PayPal ecosystem. Attackers could potentially redirect users to malicious sites, harvest session cookies, or inject malware that persists across user sessions. The vulnerability affects users who interact with the PayPal invoice SDK samples, particularly developers who might inadvertently test the permissions functionality with malicious input. The attack surface is expanded when considering that this vulnerability exists within a widely-used payment processing library, meaning that any application integrating this SDK could be compromised, creating cascading security implications across multiple systems.
Security mitigation strategies for CVE-2017-6213 should focus on implementing comprehensive input validation and output encoding mechanisms. The recommended approach involves sanitizing all user inputs through proper validation routines and applying appropriate HTML encoding before rendering any user-supplied data in web responses. Organizations should implement Content Security Policy headers to limit script execution and prevent unauthorized code injection. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1566 which covers social engineering through malicious links. Patch management protocols should prioritize updating the paypal/invoice-sdk-php library to versions that address this specific XSS vulnerability, while developers should adopt secure coding practices that prevent similar issues in custom implementations. Regular security testing including dynamic application security testing and manual code reviews should be implemented to identify and remediate similar input validation weaknesses in the application's attack surface.