CVE-2005-4310 in Tectia Server
Summary
by MITRE
SSH Tectia Server 5.0.0 (A, F, and T), when allowing host-based authentication only, allows users to log in with the wrong credentials.
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Analysis
by VulDB Data Team • 06/12/2019
The vulnerability identified as CVE-2005-4310 affects SSH Tectia Server versions 5.0.0 in its A, F, and T configurations, representing a critical authentication bypass flaw that undermines the fundamental security model of secure shell communications. This issue specifically manifests when the server is configured to permit host-based authentication exclusively, creating a scenario where unauthorized users can gain system access despite providing incorrect authentication credentials. The flaw fundamentally compromises the integrity of the authentication process by allowing credential mismatches to be accepted as valid authentication attempts.
The technical root cause of this vulnerability stems from improper validation of authentication credentials within the host-based authentication mechanism. When SSH Tectia Server operates in host-based authentication mode, it should verify that incoming connection requests originate from authorized hosts and that the associated user credentials match the expected values. However, the implementation contains a logic flaw where the system fails to properly validate the credential combination, enabling attackers to bypass the authentication checks entirely. This represents a classic case of insufficient input validation and authentication control flow management, aligning with CWE-284 access control vulnerabilities that permit unauthorized access through improper privilege management.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the trust model that secure shell protocols are designed to maintain. Attackers exploiting this flaw can establish persistent access to systems without proper authentication, potentially leading to complete system compromise, data exfiltration, and lateral movement within network environments. The vulnerability is particularly dangerous because it operates silently without generating authentication failure logs, making detection difficult and allowing attackers to maintain access undetected for extended periods. This characteristic places the vulnerability in the ATT&CK framework under privilege escalation and persistence techniques, as it enables unauthorized users to gain elevated access without proper authorization.
Organizations utilizing SSH Tectia Server in host-based authentication mode face significant risk exposure from this vulnerability, as it essentially renders the authentication mechanism ineffective. The flaw affects systems where administrators have configured the server to trust specific hosts for authentication purposes, believing that this configuration provides adequate security. However, the vulnerability demonstrates that even when host-based authentication is properly configured, the underlying implementation fails to enforce proper credential validation. Mitigation strategies should include immediate patching of affected systems, implementation of additional authentication layers, and enhanced monitoring of authentication events to detect anomalous access patterns. Organizations should also consider implementing network segmentation and additional access controls to limit the potential impact of such authentication bypasses. The vulnerability highlights the critical importance of thorough testing of authentication mechanisms, particularly in security-critical applications where credential validation failures can lead to complete system compromise.