CVE-2017-11879 in ASP.NET Core
Summary
by MITRE
ASP.NET Core 2.0 allows an attacker to steal log-in session information such as cookies or authentication tokens via a specially crafted URL aka "ASP.NET Core Elevation Of Privilege Vulnerability".
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Analysis
by VulDB Data Team • 01/23/2021
The vulnerability identified as CVE-2017-11879 represents a critical elevation of privilege flaw within ASP.NET Core 2.0 frameworks that enables attackers to harvest sensitive authentication data through manipulated web requests. This vulnerability specifically targets the session management mechanisms employed by the framework, creating a pathway for unauthorized access to user credentials and authentication tokens that are typically protected by the application's security controls. The flaw manifests when the system processes specially crafted URLs that exploit weaknesses in how authentication information is handled during session establishment and maintenance phases.
The technical root cause of this vulnerability stems from inadequate input validation and improper handling of authentication tokens within the ASP.NET Core 2.0 pipeline. When users navigate to maliciously constructed URLs, the framework fails to properly sanitize or validate the parameters being passed, allowing attackers to manipulate session cookies or authentication tokens that are typically stored in HTTP headers or URL parameters. This flaw falls under the category of CWE-20, which describes improper input validation, and specifically relates to CWE-352, which addresses cross-site request forgery vulnerabilities, though the implementation here focuses on session token manipulation rather than CSRF attacks. The vulnerability enables attackers to construct URLs that can be used to extract session identifiers and authentication tokens from legitimate user sessions.
The operational impact of CVE-2017-11879 extends beyond simple credential theft, as it can lead to complete account compromise and unauthorized access to protected resources within applications built on the ASP.NET Core 2.0 framework. Attackers can leverage this vulnerability to impersonate legitimate users, access sensitive data, perform unauthorized transactions, and potentially escalate their privileges within the application environment. The attack vector is particularly dangerous because it can be executed through simple web navigation without requiring complex exploitation techniques or specialized tools, making it accessible to attackers with minimal technical expertise. This vulnerability directly maps to ATT&CK technique T1548.002, which covers abuse of cloud platforms and session management flaws, and T1566.001, which addresses spearphishing with links, as the malicious URLs can be delivered through social engineering campaigns.
Organizations running applications built on ASP.NET Core 2.0 are particularly vulnerable to this attack vector, especially those that rely heavily on session-based authentication or token management for user access control. The vulnerability affects applications that do not properly implement secure session handling practices or that fail to validate the integrity of authentication tokens passed through URL parameters. Mitigation strategies should include implementing proper input validation for all URL parameters, employing secure session management practices that do not rely on URL-based token passing, and ensuring that authentication tokens are properly encrypted and validated before being processed by the application framework. Additionally, organizations should consider implementing web application firewalls, monitoring for unusual URL patterns, and conducting regular security assessments to identify and remediate similar vulnerabilities in their web applications. The vulnerability underscores the importance of following secure coding practices as outlined in OWASP Top Ten and NIST cybersecurity guidelines for web application security.