CVE-2020-20701 in S-CMS PHP
Summary
by MITRE • 07/30/2021
A stored cross site scripting (XSS) vulnerability in /app/config/of S-CMS PHP v3.0 allows attackers to execute arbitrary web scripts or HTML via a crafted payload.
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Analysis
by VulDB Data Team • 08/06/2021
The stored cross site scripting vulnerability identified as CVE-2020-20701 resides within the S-CMS PHP v3.0 application's configuration handling system at the /app/config/ path. This flaw represents a critical security weakness that enables attackers to inject malicious scripts into the application's persistent storage mechanisms. The vulnerability specifically affects how the CMS processes and stores user-supplied input, creating an environment where malicious code can be permanently embedded within the system's configuration files. When legitimate users access pages that retrieve and display this stored data, the malicious scripts execute in their browsers, potentially compromising the entire user session and system integrity.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output sanitization within the application's configuration management module. Attackers can craft malicious payloads that exploit the CMS's failure to properly escape or filter user input before storing it in the database or configuration files. The vulnerability operates as a stored XSS attack because the malicious code is not merely reflected in response headers but is permanently saved within the application's data storage, making it persistent across multiple user sessions. This characteristic distinguishes it from reflected XSS attacks where the malicious code must be injected with each request, making stored XSS particularly dangerous as it affects all users who interact with the compromised content.
The operational impact of this vulnerability extends far beyond simple script execution, creating significant risks for organizations utilizing S-CMS PHP v3.0. Attackers can leverage this weakness to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious websites, or even establish persistent backdoors within the compromised system. The stored nature of the vulnerability means that a single successful attack can compromise multiple users over extended periods, as the malicious code remains active in the system's configuration files. This vulnerability directly violates security principles outlined in CWE-79, which specifically addresses cross site scripting flaws, and aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments or links, as attackers may exploit this vulnerability to deliver malicious payloads to unsuspecting users.
Organizations affected by CVE-2020-20701 should implement immediate mitigations including comprehensive input validation, output encoding, and proper sanitization of all user-supplied data before storage. The recommended approach involves implementing Content Security Policy headers, utilizing secure coding practices for input handling, and conducting thorough security testing of all configuration management components. Additionally, organizations should consider implementing web application firewalls to detect and block suspicious payloads, perform regular security audits of configuration files, and establish proper access controls to limit who can modify system configurations. The vulnerability demonstrates the critical importance of validating and sanitizing all input within web applications, particularly in administrative interfaces where configuration data is processed, as highlighted in OWASP Top 10 2017 category A03: Injection and the broader security framework established by NIST SP 800-53 control families related to input validation and output encoding.