Explanation/Notes: Ordinarily, telecommuters are not skilled on security-related issues, and may inadvertently or negligently leave their computer system and the corporate network open to attack. Telecommuters therefore pose a serious security risk if they are not properly trained. In addition to installing antivirus and anti-Trojan Horse software to protect against malicious code, a firewall is necessary to block any hostile users from obtaining access to any services enabled on the telecommuter's system.