CVE-2019-17488 in Symphony
Summary
by MITRE
b3log Symphony (aka Sym) before 3.6.0 has XSS via the HTTP User-Agent header.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability CVE-2019-17488 represents a cross-site scripting flaw in the b3log Symphony web application framework that affects versions prior to 3.6.0. This issue specifically manifests through improper input validation of the HTTP User-Agent header, which is commonly used by web servers to identify client software and browser characteristics. The User-Agent header is typically sent by browsers and other HTTP clients to provide information about their identity, version, and capabilities to the server. In the context of web applications, this header is often processed and displayed within administrative interfaces or log monitoring systems without adequate sanitization.
The technical implementation of this vulnerability stems from insufficient sanitization of user-supplied input within the Symphony framework's processing logic. When the application receives HTTP requests containing User-Agent headers, it fails to properly escape or validate the content before rendering it in web pages or storing it in databases. This oversight creates an opportunity for attackers to inject malicious scripts that can execute in the context of other users' browsers who view affected pages. The vulnerability is classified as a classic reflected cross-site scripting issue where the malicious payload is embedded in the User-Agent header and subsequently reflected back to users through the application's interface.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious sites. An attacker could craft a User-Agent header containing JavaScript code that, when processed by the Symphony application, would execute in the browser of any administrator or user who views the affected administrative panels. This could lead to unauthorized access to sensitive administrative functions, data exfiltration, and potential complete compromise of the application environment. The vulnerability affects the confidentiality, integrity, and availability of the system by creating an entry point for malicious actors to exploit.
Security professionals should note that this vulnerability aligns with CWE-79 which describes improper neutralization of input during web output creation, and maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments or links. The recommended mitigations include upgrading to Symphony version 3.6.0 or later, implementing proper input sanitization for all user-supplied headers, and deploying web application firewalls to detect and block malicious User-Agent patterns. Organizations should also consider implementing Content Security Policy headers to limit script execution and regularly audit their applications for similar input validation flaws. Additionally, monitoring logs for unusual User-Agent patterns and implementing proper output encoding for all dynamic content can significantly reduce the risk of exploitation. The vulnerability demonstrates the critical importance of validating all input sources, including HTTP headers, and applying defense-in-depth strategies to protect web applications from common injection attacks.