CVE-2014-1771 in Internet Explorer
Summary
by MITRE
SChannel in Microsoft Internet Explorer 6 through 11 does not ensure that a server's X.509 certificate is the same during renegotiation as it was before renegotiation, which allows man-in-the-middle attackers to obtain sensitive information or modify TLS session data via a "triple handshake attack," aka "TLS Server Certificate Renegotiation Vulnerability."
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Analysis
by VulDB Data Team • 09/12/2025
The CVE-2014-1771 vulnerability represents a critical weakness in Microsoft Internet Explorer's Secure Channel implementation that fundamentally undermines the security assurances provided by TLS protocol renegotiation. This flaw exists within the SChannel API component that handles secure communications, specifically affecting Internet Explorer versions 6 through 11. The vulnerability stems from improper certificate validation during the renegotiation process, creating a window where attackers can exploit the trust relationship between client and server. The issue is particularly dangerous because it operates at the protocol level, affecting the core security mechanisms that protect data integrity and authentication in encrypted communications. This weakness enables attackers to perform sophisticated man-in-the-middle attacks by exploiting the inconsistency in certificate validation between initial connection and subsequent renegotiation phases.
The technical flaw manifests when a TLS session undergoes renegotiation, which is a legitimate protocol feature used for various purposes including authentication refresh or parameter updates. During normal operation, SChannel should maintain consistency in certificate validation throughout the session lifecycle, but this vulnerability allows the server certificate to change during renegotiation without proper verification. This creates what cybersecurity professionals refer to as a "triple handshake attack" where an attacker can manipulate the certificate presented during renegotiation, potentially presenting a malicious certificate while maintaining the appearance of legitimate communication. The vulnerability is classified under CWE-300 as "Communication Channel Security Weakness" and specifically relates to "Lack of Certificate Validation During Renegotiation" which is a well-documented pattern in cryptographic protocol implementations. The flaw exploits the trust model inherent in TLS renegotiation, where the protocol assumes that if a certificate was valid at the start of the session, it remains valid throughout renegotiation.
The operational impact of CVE-2014-1771 extends far beyond simple data interception, as it enables attackers to modify TLS session data while maintaining the appearance of legitimate communication. This vulnerability particularly affects web applications that rely on secure session management, including financial transactions, email communications, and enterprise applications where sensitive data flows through TLS-protected channels. Attackers can leverage this weakness to perform session hijacking, inject malicious content, or capture sensitive information without detection, as the compromised system maintains the illusion of secure communication. The vulnerability affects a wide range of systems since Internet Explorer 6 through 11 were widely deployed across enterprise environments, making the potential attack surface extremely broad. Organizations using older versions of Internet Explorer face heightened risk because these versions lack proper certificate consistency validation during TLS renegotiation, creating persistent security gaps that attackers can exploit to compromise entire communication sessions.
Mitigation strategies for CVE-2014-1771 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. Microsoft released patches for this vulnerability through their regular security updates, but organizations should also implement network monitoring to detect anomalous certificate behavior during renegotiation events. The recommended approach includes disabling TLS renegotiation where possible, implementing certificate pinning mechanisms, and ensuring that all systems are updated to versions that properly validate certificates throughout the session lifecycle. Organizations should also consider deploying network security solutions that can detect and block suspicious certificate changes during renegotiation. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and defense evasion, as attackers can leverage the compromised trust relationship to maintain persistent access while avoiding detection. The vulnerability highlights the importance of proper protocol implementation and the need for continuous security testing of cryptographic components to prevent such fundamental flaws from persisting in widely used software implementations.