CVE-2018-16758 in tinc
Summary
by MITRE
Missing message authentication in the meta-protocol in Tinc VPN version 1.0.34 and earlier allows a man-in-the-middle attack to disable the encryption of VPN packets.
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Analysis
by VulDB Data Team • 05/25/2023
The vulnerability identified as CVE-2018-16758 represents a critical security flaw in the Tinc VPN software ecosystem that fundamentally undermines the integrity and confidentiality of network communications. This issue affects versions 1.0.34 and earlier, where the meta-protocol implementation lacks proper message authentication mechanisms. The absence of cryptographic verification allows malicious actors to intercept and manipulate communications between VPN nodes, creating a significant attack surface that compromises the core security promises of the VPN infrastructure.
The technical implementation flaw resides in the meta-protocol layer of Tinc VPN where authentication checks are either absent or insufficiently implemented. This vulnerability specifically targets the message authentication process that should validate the integrity and origin of communications between VPN peers. Without proper authentication, attackers can inject malicious packets into the network traffic stream, potentially disrupting communication channels and disabling encryption mechanisms that are fundamental to VPN security. The vulnerability operates at a protocol level, affecting how the software handles authentication tokens and cryptographic signatures during the establishment and maintenance of secure connections.
From an operational perspective, this vulnerability creates a severe man-in-the-middle attack vector that can be exploited by adversaries positioned within the network infrastructure or those who have gained access to network traffic. The impact extends beyond simple data interception, as the attacker can actively disable encryption, rendering the VPN connection vulnerable to eavesdropping and data manipulation. This weakness undermines the entire purpose of using VPN technology for secure communications, particularly affecting users who rely on Tinc VPN for protecting sensitive information and maintaining privacy in their network communications.
The security implications of this vulnerability align with CWE-310, which addresses cryptographic weaknesses in authentication mechanisms, and can be mapped to ATT&CK technique T1041 for data encryption for exfiltration. Organizations using affected Tinc VPN versions face significant risk of unauthorized access to their network traffic, potential data breaches, and compromise of sensitive communications. The vulnerability demonstrates a critical gap in the security model where the system assumes trust in communication channels without proper verification mechanisms. Mitigation strategies should include immediate upgrade to patched versions of Tinc VPN, implementation of additional network monitoring for anomalous traffic patterns, and consideration of alternative VPN solutions with robust authentication protocols. Network administrators must also conduct thorough security assessments of their VPN infrastructure to identify and remediate similar authentication gaps that may exist in other network security components.