CVE-2002-2125 in Internet Explorer
Summary
by MITRE
Internet Explorer 6.0 does not warn users when an expired certificate authority (CA) certificate is submitted to the user and a newer CA certificate is in the user s local repository, which could allow remote attackers to decrypt web sessions via a man-in-the-middle (MITM) attack.
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Analysis
by VulDB Data Team • 07/10/2024
The vulnerability described in CVE-2002-2125 represents a critical security flaw in Internet Explorer 6.0's certificate validation mechanism that directly impacts the integrity of secure web communications. This issue stems from the browser's failure to properly alert users when encountering expired certificate authority certificates, creating a significant gap in the trust model that attackers can exploit. The vulnerability specifically affects the certificate validation process where the browser does not warn users when an expired CA certificate is presented by a web server, even when a newer, valid CA certificate exists locally in the user's certificate repository. This behavior fundamentally undermines the security assurances that SSL/TLS connections are designed to provide, as it allows malicious actors to present expired certificates without triggering user warnings that would normally prompt caution.
The technical flaw manifests in Internet Explorer's certificate chain validation algorithm which does not properly compare the presented certificate against the local certificate store to identify expired CA certificates that might be used to impersonate legitimate authorities. According to CWE-295, this vulnerability falls under improper certificate validation, where the system fails to properly validate the authenticity and timeliness of certificates used in secure communications. The implementation defect lies in the browser's certificate trust model where expired certificates are not adequately flagged as suspicious, particularly when newer versions of the same CA certificate exist locally. This creates a dangerous scenario where the browser's security warnings are bypassed, allowing attackers to establish fraudulent secure connections that appear legitimate to users who may not be aware of the expired certificate status.
The operational impact of this vulnerability is severe and directly enables man-in-the-middle attack scenarios where remote attackers can intercept and decrypt web sessions without user awareness. When an attacker can present an expired CA certificate that is accepted by the vulnerable browser, they can establish a trusted connection with users and subsequently decrypt their web traffic, potentially gaining access to sensitive information including login credentials, personal data, and financial information. This vulnerability aligns with ATT&CK technique T1573.002 for "Encrypted Channel" and represents a critical failure in the certificate validation process that allows attackers to establish trusted communication channels without proper user notification. The attack vector specifically exploits the trust relationship between the browser and certificate authorities, where the browser's failure to warn users about expired certificates creates a window for attackers to conduct successful MITM operations.
The security implications extend beyond simple session interception to encompass potential data breaches and credential theft across all HTTPS communications. Users operating with Internet Explorer 6.0 are particularly vulnerable as the browser's certificate validation is fundamentally flawed, allowing attackers to impersonate legitimate websites and gain access to user sessions. This vulnerability demonstrates the critical importance of proper certificate validation and user warnings in maintaining secure communications, as the lack of explicit alerts when expired certificates are encountered creates a false sense of security. Organizations and individuals using this vulnerable browser configuration are at significant risk of having their sensitive communications intercepted and decrypted by malicious actors who exploit this validation flaw. The vulnerability also highlights the importance of maintaining up-to-date certificate repositories and proper certificate validation policies that would normally prevent such scenarios from occurring in properly configured systems.