Although Apple is selling its new Mac OS X Leopard operating system on its improved security, researchers at Heise Security have already found fault with its firewall. Unlike with Windows Vista, the Apple firewall is not enabled by default and must be enabled by the end user. Even if you had the firewall enabled in a previous version of the Mac OS X, after an upgrade to Leopard the firewall will again be set to “Allow all incoming connections.” It will be disabled.

According to Jürgen Schmidt, editor in chief at Heise Security, if you enable the Apple firewall and set it to “Block all incoming connections,” access from the Internet to certain internal system services will still be allowed. As an example, he said that his team was able to query the NetBIOS Naming Service over a Lan network even with full blocking enabled. The team was also unable to specifically enable UDP filtering within Leopard, which should block access to NetBIOS.