CVE-2011-4408 in Linux
Summary
by MITRE
The Single Sign On Client (ubuntu-sso-client) for Ubuntu 11.04 and 11.10 does not properly validate SSL certificates when using HTTPS, which allows remote attackers to spoof a server and modify or read sensitive data via a man-in-the-middle (MITM) attack.
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Analysis
by VulDB Data Team • 12/04/2021
The vulnerability identified as CVE-2011-4408 affects the Single Sign On Client component known as ubuntu-sso-client in Ubuntu operating systems version 11.04 and 11.10. This flaw represents a critical security weakness in the client's handling of secure communications, specifically within the SSL certificate validation process. The issue stems from insufficient certificate validation mechanisms that fail to properly verify the authenticity and integrity of SSL certificates presented by remote servers during HTTPS connections. This deficiency creates a significant attack surface that malicious actors can exploit to compromise the security of user sessions and sensitive data transmissions.
The technical flaw manifests in the client's inability to perform adequate SSL certificate validation during HTTPS communication establishment. When the ubuntu-sso-client attempts to connect to a server using HTTPS, it does not properly verify the certificate chain, expiration dates, or cryptographic signatures that should confirm the server's identity. This weakness directly aligns with CWE-295, which addresses improper certificate validation in security protocols. The vulnerability enables attackers to execute man-in-the-middle attacks by presenting fraudulent SSL certificates that appear legitimate to the vulnerable client, thereby bypassing the expected security controls designed to protect against unauthorized access and data interception.
The operational impact of this vulnerability is severe and multifaceted, affecting users who rely on Ubuntu's Single Sign On services for authentication and secure access to various applications and online resources. Attackers exploiting this weakness can intercept and modify sensitive data transmitted between the client and legitimate servers, potentially gaining access to user credentials, personal information, and confidential communications. The vulnerability particularly affects users of Ubuntu 11.04 and 11.10 systems who utilize the SSO client for authentication purposes, creating a persistent risk for organizations relying on these platforms. This weakness undermines the fundamental security assurances provided by HTTPS encryption and certificate-based authentication, effectively rendering the security layer ineffective against determined adversaries.
Mitigation strategies for CVE-2011-4408 should prioritize immediate system updates and patches provided by Ubuntu security teams, as the vulnerability was addressed through software updates that strengthened SSL certificate validation mechanisms. Organizations should implement network monitoring solutions to detect potential man-in-the-middle attack attempts and establish robust certificate management practices that include regular validation of SSL certificates. The remediation process involves updating the ubuntu-sso-client package to versions that include proper certificate validation routines, which aligns with ATT&CK technique T1566 for credential harvesting through phishing and social engineering. Additionally, system administrators should consider implementing additional security layers such as network intrusion detection systems and certificate pinning mechanisms to provide defense-in-depth against similar vulnerabilities. The vulnerability serves as a critical reminder of the importance of proper certificate validation in security protocols and the potential consequences of inadequate cryptographic implementation in client applications.