Cross-site scripting (XSS) vulnerabilities, particularly stored XSS, pose significant security threats in web applications, allowing attackers to hijack user sessions and steal sensitive information. By exploiting hidden input fields and using clever payloads, vulnerabilities can often be found in overlooked areas. This article illustrates a successful hunt for such a vulnerability and the critical lessons learned. Affected: web applications, user sessions
Keypoints :
- XSS vulnerabilities remain prevalent and dangerous in web security.
- Stored XSS attacks are persistent and can affect all users who load an affected page.
- Hidden input fields are often mistakenly considered secure by developers.
- The use of the pattern attribute and event handlers can expose hidden vulnerabilities.
- Validation should always occur on both client-side and server-side to ensure security.
MITRE Techniques :
- Cross-Site Scripting (T1171) – Stored XSS: An attacker uses a malicious script that gets stored in a website’s database, executing whenever a user loads the page.