CVE-2000-0064 is a vulnerability found in the cgiproc CGI script of the Nortel Contivity HTTP server version 1.0. This vulnerability allows remote attackers to cause a denial of service (DoS) condition by sending a malformed URL containing shell metacharacters to the cgiproc script. The vulnerability arises because the CGI script improperly handles input, allowing shell metacharacters to be interpreted by the underlying system shell. This can lead to the server process crashing or becoming unresponsive, effectively denying legitimate users access to the service. The attack does not require authentication and can be executed remotely over the network, making it relatively easy to exploit. The vulnerability affects only version 1.0 of the Nortel Contivity HTTP server, and no patches or fixes are available. The CVSS score of 5.0 (medium severity) reflects the fact that the impact is limited to availability (denial of service), with no direct impact on confidentiality or integrity. There are no known exploits in the wild, and the vulnerability has been publicly known since January 2000.

For European organizations using Nortel Contivity HTTP server version 1.0, this vulnerability poses a risk of service disruption due to denial of service attacks. The inability to access the HTTP server could impact business operations, especially if the server is used for critical network functions or remote access. Although the vulnerability does not allow data theft or modification, the loss of availability can lead to operational downtime, potential loss of productivity, and reputational damage. Given the age of the vulnerability and the product version affected, it is likely that most organizations have upgraded or replaced this software; however, legacy systems or specialized network appliances still in use could be vulnerable. The lack of a patch means organizations must rely on other mitigation strategies to reduce risk. The impact is more significant for organizations that rely heavily on the affected server for network connectivity or remote management.

Since no patch is available for this vulnerability, European organizations should consider the following specific mitigation steps: 1) Identify and inventory all Nortel Contivity HTTP server instances, particularly version 1.0, within the network. 2) Isolate or segment vulnerable servers from untrusted networks to limit exposure to remote attackers. 3) Implement strict input validation and filtering at network perimeter devices or web application firewalls to block malformed URLs containing shell metacharacters targeting the cgiproc script. 4) Monitor network traffic and server logs for unusual requests or repeated malformed URL attempts that could indicate exploitation attempts. 5) Where possible, upgrade or replace the affected Nortel Contivity HTTP server with a more recent, supported product version or alternative solution that does not contain this vulnerability. 6) Employ intrusion detection/prevention systems configured to detect exploitation patterns related to this vulnerability. 7) Educate network administrators about the risks and signs of exploitation to ensure timely response.