CVE-2011-3417 in .NET Framework
Summary
by MITRE
The Forms Authentication feature in the ASP.NET subsystem in Microsoft .NET Framework 1.1 SP1, 2.0 SP2, 3.5 SP1, 3.5.1, and 4.0, when sliding expiry is enabled, does not properly handle cached content, which allows remote attackers to obtain access to arbitrary user accounts via a crafted URL, aka "ASP.NET Forms Authentication Ticket Caching Vulnerability."
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 03/20/2021
The CVE-2011-3417 vulnerability represents a critical security flaw in Microsoft's ASP.NET authentication system that specifically affects versions 1.1 SP1 through 4.0 of the .NET Framework. This vulnerability exploits the Forms Authentication feature when sliding expiration is enabled, creating a scenario where attackers can manipulate cached authentication tickets to gain unauthorized access to user accounts. The flaw stems from improper handling of cached content within the authentication subsystem, which fundamentally undermines the security model designed to protect user sessions and maintain proper access controls. The vulnerability is particularly dangerous because it operates at the core authentication layer of web applications built on the .NET platform, making it applicable to a vast ecosystem of enterprise and web applications.
The technical root cause of this vulnerability lies in how ASP.NET handles cached authentication tickets when sliding expiration is configured. When sliding expiration is enabled, the system is designed to extend the validity period of authentication tickets when users perform legitimate activities, thereby maintaining active sessions without requiring constant re-authentication. However, the implementation contains a flaw where cached content is not properly invalidated or updated when authentication states change, creating a window where cached tickets can be reused or manipulated. This issue manifests when the system caches authentication data and fails to properly synchronize this cache with the actual authentication state, allowing attackers to craft specific URLs that leverage these cached tickets to impersonate legitimate users. The vulnerability is classified under CWE-284 Access Control, as it represents a weakness in the authorization mechanism that allows unauthorized access to protected resources.
The operational impact of CVE-2011-3417 extends far beyond simple privilege escalation, as it enables attackers to gain access to arbitrary user accounts within applications that rely on ASP.NET Forms Authentication with sliding expiration enabled. This vulnerability can be exploited by remote attackers without requiring any special privileges or local access, making it particularly dangerous in web environments where applications are exposed to untrusted networks. The attack surface is extensive since the vulnerability affects multiple versions of the .NET Framework, meaning that organizations running applications on any of these versions are potentially at risk. Successful exploitation can result in complete account compromise, data theft, privilege escalation, and potential lateral movement within networks where these vulnerable applications exist. The vulnerability also has implications for compliance with security standards such as those outlined in the NIST Cybersecurity Framework, as it represents a failure to maintain proper access controls and authentication integrity.
Mitigation strategies for CVE-2011-3417 require immediate attention from system administrators and security teams responsible for maintaining .NET Framework applications. The most effective immediate solution involves applying the relevant security updates and patches provided by Microsoft, which address the underlying caching mechanism flaw in the Forms Authentication implementation. Organizations should also consider disabling sliding expiration for applications that are particularly sensitive or where the risk of exploitation is high, though this may impact user experience. Additional mitigations include implementing proper session management controls, monitoring for suspicious authentication patterns, and ensuring that authentication tickets are properly validated before being accepted. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access, specifically T1078 Valid Accounts and T1566 Phishing, as attackers may use compromised accounts to gain further access to systems. Organizations should also implement network monitoring to detect unusual authentication patterns that might indicate exploitation attempts, and consider implementing additional authentication layers such as multi-factor authentication to provide defense in depth against potential exploitation of this vulnerability.