CVE-2020-20640 in ECShop
Summary
by MITRE • 06/29/2021
Cross Site Scripting (XSS) vulnerability in ECShop 4.0 due to security filtering issues, in the user.php file, we can use the html entity encoding to bypass the security policy of the safety.php file, triggering the xss vulnerability.
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Analysis
by VulDB Data Team • 07/03/2021
The CVE-2020-20640 vulnerability represents a critical cross site scripting flaw discovered in ECShop 4.0 e-commerce platform, specifically within the user.php file where inadequate input validation allows malicious actors to bypass established security measures. This vulnerability stems from insufficient sanitization of user-supplied data, creating an exploitable condition that directly impacts the application's security posture. The flaw manifests when attackers leverage html entity encoding techniques to circumvent the security policies implemented in the safety.php file, effectively neutralizing the protective mechanisms designed to prevent malicious script injection. The vulnerability operates under CWE-79 which classifies it as a classic cross site scripting weakness, where the application fails to properly escape or validate user input before rendering it in web pages. From an operational perspective, this vulnerability creates a significant risk for ECShop installations as it allows attackers to inject malicious javascript code that can execute in the context of other users' browsers, potentially leading to session hijacking, data theft, or unauthorized administrative access. The attack vector specifically targets the user.php file where user registration or profile modification functionality exists, making it particularly dangerous as it can be exploited during normal user interactions. Security researchers have identified that the bypass mechanism relies on the application's failure to consistently apply encoding transformations across all input processing stages, creating a gap where html entities can be used to evade validation filters. This weakness aligns with ATT&CK technique T1059.001 which describes the use of scripting languages for code injection, specifically targeting web applications where user input is not properly sanitized. The vulnerability's impact extends beyond simple script execution as it can enable more sophisticated attacks including credential theft through cookie manipulation, redirection to malicious sites, or even privilege escalation within the application's user management system. The root cause lies in the inconsistent application of security controls where the safety.php file implements some filtering mechanisms but fails to account for encoding bypass techniques that allow attackers to submit malicious payloads that appear to be legitimate input. This creates a dangerous scenario where the security layer becomes ineffective against sophisticated attack methods that exploit the gap between input validation and output rendering processes. The vulnerability demonstrates a fundamental flaw in the application's security architecture where multiple layers of protection are bypassed through simple encoding techniques, highlighting the importance of comprehensive input validation and the principle of least privilege in web application security. Organizations running ECShop 4.0 should immediately implement mitigations including enhanced input sanitization, proper output encoding, and regular security audits to prevent exploitation of this vulnerability. The flaw also underscores the critical need for security measures that consider all possible encoding methods attackers might employ to bypass traditional filtering approaches, emphasizing the importance of defense in depth strategies that protect against multiple attack vectors simultaneously.