CVE-2015-6099 in .NET Framework
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in ASP.NET in Microsoft .NET Framework 4, 4.5, 4.5.1, 4.5.2, and 4.6 allows remote attackers to inject arbitrary web script or HTML via a crafted value, aka ".NET Elevation of Privilege Vulnerability."
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 06/27/2022
The CVE-2015-6099 vulnerability represents a critical cross-site scripting flaw within Microsoft's ASP.NET framework affecting multiple versions including .NET Framework 4, 4.5, 4.5.1, 4.5.2, and 4.6. This vulnerability falls under the CWE-79 category of Cross-Site Scripting and operates as an elevation of privilege vector that enables remote attackers to inject malicious web scripts or HTML content into affected applications. The flaw specifically exploits how the framework handles certain crafted input values, creating opportunities for attackers to execute arbitrary code within the context of a user's browser session.
The technical exploitation of this vulnerability occurs when ASP.NET applications fail to properly sanitize or validate user input that gets rendered back to users through web pages. Attackers can craft malicious payloads that, when processed by the vulnerable framework, get executed in the victim's browser environment. This creates a persistent threat vector where malicious scripts can steal session cookies, perform actions on behalf of users, redirect traffic, or even establish backdoor connections. The vulnerability is particularly dangerous because it leverages the inherent trust relationship between the web application and the user's browser, allowing attackers to bypass traditional security controls.
The operational impact of CVE-2015-6099 extends beyond simple script injection, as it can enable sophisticated attack chains within the broader ATT&CK framework. Attackers can use this vulnerability to establish persistent access through session hijacking, perform data exfiltration, or create malicious redirects that lead to further exploitation. The vulnerability affects applications that rely on ASP.NET's default request validation mechanisms, making it particularly widespread across enterprise environments that utilize Microsoft's web technologies. Organizations running affected versions of the .NET Framework face significant risk of unauthorized access, data breaches, and potential compromise of entire web application infrastructures.
Mitigation strategies for this vulnerability should include immediate patching of affected systems with Microsoft's security updates, implementation of robust input validation and output encoding mechanisms, and deployment of web application firewalls to detect and block malicious payloads. Organizations should also conduct comprehensive vulnerability assessments to identify all applications running on affected framework versions and implement proper security headers including Content Security Policy to limit script execution capabilities. Additionally, security monitoring should be enhanced to detect unusual patterns of script injection attempts, and regular security training should be provided to development teams to prevent insecure coding practices that could lead to similar vulnerabilities in custom applications.