Diligence Points out Firewall Vulnerability
- By Scott Bekker
- November 10, 1998
Diligence (London, www.diligence.co.uk
), a security consulting firm discovered a vulnerability in a stateful packet filter-based firewall.
This latest discovery found that a stateful packet inspection firewall allows several types of IP traffic, including DNS, ICMP and RIP to flow unchecked through the firewall to attack systems. Diligence demonstrated that these holes can be exploited with the controversial BackOrifice Trojan horse program. The problem can be patched by changing the default settings.
"Secure firewall design principles require that everything not expressly permitted is prohibited," says Frank Willoughby, president, Fortified Networks Inc. "Therefore, a firewall’s default security rules at installation time should block all network traffic from passing through the firewall, especially DNS, IMCP and RIP."
These vulnerabilities are not typical of all firewalls. Application-level proxy firewalls, for instance, create a secure, fail-safe environment.
However, in making this announcement, Diligence joins the ranks of independent security watch groups that in the past few months have identified at least five critical vulnerabilities associated with firewalls based on stateful packet inspection architecture. Other documented vulnerabilities include unencrypted remote management, stealth scanning and reserved word problems. – Thomas Sullivan, Staff Reporter/Reviews Editor
Scott Bekker is editor in chief of Redmond Channel Partner magazine.