CVE-2002-0994 in SunPCi II VNC
Summary
by MITRE
SunPCi II VNC uses a weak authentication scheme, which allows remote attackers to obtain the VNC password by sniffing the random byte challenge, which is used as the key for encrypted communications.
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Analysis
by VulDB Data Team • 03/08/2025
The vulnerability described in CVE-2002-0994 affects SunPCi II VNC implementations that utilize a weak authentication mechanism. This flaw represents a significant security weakness in remote desktop protocol implementations that rely on outdated cryptographic practices. The vulnerability specifically targets the authentication process where the system employs a random byte challenge that serves as the encryption key for secure communications, creating an exploitable weakness that can be leveraged by remote attackers.
The technical flaw stems from the implementation of a weak cryptographic scheme where the random byte challenge used for authentication is directly employed as the encryption key. This approach violates fundamental cryptographic principles and creates a predictable vulnerability that allows attackers to capture and analyze the challenge-response mechanism. The weakness enables man-in-the-middle attacks where an attacker can intercept network traffic and extract the authentication credentials through passive network sniffing techniques. This vulnerability aligns with CWE-326, which addresses weak encryption and improper cryptographic key handling, and represents a classic example of how cryptographic key derivation can be compromised when the same value is used for both authentication and encryption purposes.
The operational impact of this vulnerability is substantial as it allows remote attackers to gain unauthorized access to systems protected by SunPCi II VNC implementations. Once an attacker successfully sniffs the random byte challenge, they can potentially reconstruct the authentication credentials and gain full access to the remote desktop session. This creates a critical security risk for organizations that rely on VNC for remote administration, as it undermines the fundamental security assumptions of the remote access protocol. The vulnerability can be exploited from any network location where the attacker has access to the network traffic, making it particularly dangerous in environments where network monitoring is insufficient or where unencrypted communication channels exist.
Mitigation strategies for this vulnerability should focus on implementing stronger authentication mechanisms and cryptographic practices that do not rely on the same values for both authentication and encryption purposes. Organizations should upgrade to modern VNC implementations that support strong cryptographic protocols such as TLS encryption and proper key management practices. The implementation of additional network security measures including encrypted communication channels, network segmentation, and proper access controls can help reduce the attack surface. This vulnerability demonstrates the importance of following security standards such as those outlined in the NIST Cybersecurity Framework and aligns with ATT&CK technique T1071.004 for application layer protocol tunneling, where attackers exploit weak authentication to establish unauthorized access to remote systems. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar weaknesses in remote access implementations across the organization's infrastructure.