CVE-2000-0478 in Norton Antivirus
Summary
by MITRE
In some cases, Norton Antivirus for Exchange (NavExchange) enters a "fail-open" state which allows viruses to pass through the server.
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Analysis
by VulDB Data Team • 04/05/2019
The vulnerability described in CVE-2000-0478 represents a critical security flaw in Norton Antivirus for Exchange software that fundamentally compromises the integrity of email server protection mechanisms. This issue manifests when the antivirus solution enters a fail-open state, which is a dangerous condition where the system continues to allow email traffic to pass through without proper virus scanning. The fail-open behavior essentially creates a security bypass that enables malicious code to traverse the email server undetected, undermining the core purpose of endpoint protection. This vulnerability is particularly concerning in exchange server environments where email traffic flows continuously and contains sensitive organizational data.
The technical flaw underlying this vulnerability stems from improper error handling within the NavExchange antivirus engine. When the antivirus system encounters certain conditions that cause it to fail in performing virus scans, instead of implementing a fail-safe mechanism that blocks email traffic, the software transitions into a state where it permits all incoming and outgoing messages to pass through the server without inspection. This behavior violates fundamental security principles and creates an exploitable condition where attackers can leverage the fail-open state to deliver malware through email channels. The vulnerability is classified under CWE-1004 which relates to security-relevant changes to the software configuration, and it directly impacts the availability and integrity of email communications within enterprise environments.
The operational impact of this vulnerability extends far beyond simple email delivery issues, as it creates a significant attack surface that malicious actors can exploit to compromise entire email infrastructures. Organizations using affected versions of Norton Antivirus for Exchange face the risk of widespread malware infections through email channels, potentially leading to data breaches, unauthorized access to sensitive information, and complete compromise of email server environments. The fail-open state can persist for extended periods without detection, allowing multiple infected emails to pass through the system before administrators recognize the security degradation. This vulnerability aligns with ATT&CK technique T1190 which involves exploiting vulnerabilities in email servers and T1078 which covers valid accounts usage, as the compromised system may be used to send malicious emails or establish persistence within the network.
Mitigation strategies for this vulnerability require immediate implementation of multiple defensive measures including immediate patching of affected Norton Antivirus for Exchange versions, implementation of redundant antivirus solutions, and configuration of proper monitoring to detect fail-open states. Organizations should establish automated alerting mechanisms that monitor antivirus engine status and ensure that any transition into fail-open states triggers immediate administrative intervention. Network segmentation and additional email filtering solutions should be deployed as compensating controls to protect against the specific threat vector. Regular security audits of antivirus configurations and system status monitoring are essential to prevent exploitation of this vulnerability, as the fail-open state can occur due to various conditions including resource exhaustion, corrupted database files, or software conflicts with other system components. The vulnerability underscores the critical importance of proper fail-safe mechanisms in security software and demonstrates the potential consequences when such safeguards are absent from critical infrastructure protection systems.