CVE-2012-4545 in ELinks
Summary
by MITRE
The http_negotiate_create_context function in protocol/http/http_negotiate.c in ELinks 0.12 before 0.12pre6, when using HTTP Negotiate or GSS-Negotiate authentication, delegates user credentials through GSSAPI, which allows remote servers to authenticate as the client via the delegated credentials.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability described in CVE-2012-4545 affects ELinks 0.12 versions prior to 0.12pre6 and relates to improper handling of GSSAPI authentication contexts during HTTP Negotiate authentication. This flaw exists within the http_negotiate_create_context function located in protocol/http/http_negotiate.c, which is responsible for managing authentication negotiations between the client and remote servers. The issue stems from the application's failure to properly manage credential delegation when establishing secure connections, creating a significant security risk for users who authenticate through GSSAPI-enabled protocols.
The technical flaw manifests when ELinks processes HTTP Negotiate or GSS-Negotiate authentication mechanisms, where the application incorrectly delegates user credentials to remote servers without proper validation or restriction of credential usage. This delegation occurs through the GSSAPI framework, which is designed to provide secure authentication services across networked applications. When a client connects to a server using these authentication methods, the system creates a GSSAPI context that should normally be restricted to the specific server being authenticated against. However, the vulnerability allows remote servers to obtain and utilize delegated credentials to impersonate the client, effectively bypassing the normal authentication boundaries that should protect user credentials.
The operational impact of this vulnerability is severe as it enables remote attackers to perform unauthorized authentication on behalf of legitimate users. This credential delegation attack vector allows malicious servers to gain access to resources that would normally require valid user credentials, potentially leading to unauthorized data access, privilege escalation, and further network compromise. The vulnerability is particularly dangerous in environments where users access multiple services through a single authentication context, as it could enable attackers to move laterally across systems using stolen delegated credentials. According to CWE-284, this represents an improper access control issue where the system fails to properly restrict access to authentication credentials.
The implications of this vulnerability extend beyond simple credential theft, as it undermines the fundamental security model of GSSAPI authentication. The attack follows patterns consistent with credential delegation abuse techniques documented in various security frameworks, including those related to Kerberos authentication mechanisms. When users authenticate to servers using GSSAPI, they expect their credentials to be used only for the specific authentication transaction and not to be available for reuse by other systems. The vulnerability essentially removes this protection layer, making the authentication process vulnerable to man-in-the-middle attacks and credential harvesting. Organizations using ELinks for web browsing or web-based application access are particularly at risk, as this vulnerability can be exploited without requiring special privileges or advanced technical knowledge from the attacker.
Mitigation strategies for this vulnerability include immediate upgrading to ELinks version 0.12pre6 or later, which contains the necessary patches to properly handle GSSAPI credential delegation. System administrators should also implement network monitoring to detect suspicious authentication patterns and credential usage that might indicate exploitation attempts. Additional protective measures include configuring network firewalls to restrict access to GSSAPI-enabled services, implementing proper certificate validation procedures, and educating users about the risks of accessing untrusted websites. The vulnerability highlights the importance of proper credential management in authentication protocols and demonstrates how seemingly minor implementation flaws can create significant security risks. Organizations should also consider implementing additional authentication layers or using alternative authentication mechanisms that do not rely on potentially vulnerable credential delegation models. This vulnerability serves as a reminder of the critical importance of proper security testing and validation of authentication mechanisms, particularly those involving complex security frameworks like GSSAPI and Kerberos.