Don't leave it all to the firewall

摘要

Although firewalls form the first line of defence for most companies, it is becoming clear that a layered approach is vital to cope with a battlefront that is becoming much more mobile. Firewalls are no longer sufficient to protect a corporate network from viruses, system penetration, spoofing, data and network sabotage, and denial of service attacks. The majority of large companies have firewalls in place and security experts still consider they should form the first line of defence in a corporate IT security policy. But firewalls cannot stop everything; they need to allow data to pass through into a network and that is what makes them vulnerable. Bob Walder, director of the independent NSS Group security testing labs, says, "The problem is that many exploits take advantage of the weaknesses in the protocols that are allowed through the firewall perimeters." One such problem area is the web server. "Once the web server has been compromised, this can be used as a springboard to launch additional attacks on other internal servers," he says.