CVE-2000-0477 in Norton Antivirus
Summary
by MITRE
Buffer overflow in Norton Antivirus for Exchange (NavExchange) allows remote attackers to cause a denial of service via a .zip file that contains long file names.
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Analysis
by VulDB Data Team • 04/05/2019
The vulnerability identified as CVE-2000-0477 represents a critical buffer overflow flaw within Norton Antivirus for Exchange version 2000 and earlier releases. This security weakness specifically affects the email scanning functionality of the antivirus software when processing zip archive files containing excessively long filenames. The flaw exists in the way the software handles file name parsing during the decompression process, creating an exploitable condition that can be leveraged by remote attackers to disrupt service availability.
The technical implementation of this vulnerability stems from inadequate input validation within the zip file processing module of NavExchange. When the antivirus engine encounters a zip file containing filenames exceeding the allocated buffer size, the software fails to properly terminate or truncate the string data, resulting in memory corruption. This buffer overflow condition occurs during the file extraction and scanning phases, where the system attempts to store the extended filename data beyond the predefined memory boundaries. The flaw is classified under CWE-121 as a stack-based buffer overflow, representing a classic memory safety issue that can be exploited to overwrite adjacent memory locations and potentially execute arbitrary code.
From an operational perspective, this vulnerability presents a significant risk to email server availability and business continuity. Attackers can exploit this weakness by simply sending a malicious email containing a specially crafted zip file with excessively long filenames to a vulnerable server running NavExchange. The remote exploitation capability means that no local access is required, making this attack vector particularly dangerous in enterprise environments where email servers are frequently targeted. The resulting denial of service condition can render email services unavailable for extended periods, potentially affecting thousands of users within an organization.
The impact of this vulnerability extends beyond simple service disruption, as it demonstrates the critical importance of proper input validation in security software. Email antivirus solutions are typically deployed in mission-critical environments where reliability is paramount, yet this flaw reveals how even security tools can contain exploitable weaknesses. Organizations relying on older versions of Norton Antivirus for Exchange faced significant exposure, as the vulnerability could be exploited without requiring advanced technical skills or insider knowledge. The attack surface is particularly broad since email systems are essential infrastructure components that rarely go offline, making this type of denial of service attack particularly damaging.
Mitigation strategies for this vulnerability primarily focus on immediate patch application and system hardening measures. Microsoft recommended upgrading to newer versions of Norton Antivirus for Exchange that contain proper input validation and buffer management. Additionally, organizations should implement email filtering rules that restrict or scan zip file attachments before they reach the antivirus scanning engine. Network segmentation and email server hardening practices can help limit the potential impact of such attacks. The vulnerability also underscores the importance of regular security assessments and vulnerability management programs, as highlighted in the mitre ATT&CK framework under the defense evasion and execution tactics. Organizations should also consider implementing multiple layers of email security controls, including content filtering, sandboxing, and behavioral analysis to detect and prevent exploitation attempts. Regular patch management procedures and security awareness training for administrators are essential components of a comprehensive defense strategy against similar vulnerabilities in security software implementations.