Apple has patched nine security flaws in a new update for its Mac OS X operating system, including some that could allow an attacker to take over a system, and a phishing flaw in Safari that was recently fixed in the Mozilla Firefox browser.

The fixes included in Security Update 2005-003 are detailed on Apple's website. The most serious is found in the Cyrus IMAP Server, a component also included in other operating systems based on Unix and Linux, which was first disclosed in November. These flaws could allow a remote attacker to execute malicious code on a system, according to Apple and security experts such as Denmark's Secunia.

Another flaw affects Safari, the built-in Mac browser, and addresses a recently discussed attack taking advantage of a loophole in International Domain Names (IDN) support. "Support for Unicode characters within domain names (International Domain Name support) can allow maliciously registered domain names to visually appear as legitimate sites," Apple noted in its advisory.

The solution - similar to that implemented recently in Firefox - is for Safari to first consult a user-customisable list of scripts that are allowed to be displayed natively, Apple said. "The default list of allowed scripts does not include Roman look-alike scripts," the company stated. Firefox consults a list of domains which are known to have policies blocking this type of spoofing, known as a homograph attack.

The publicity around homograph attacks prompted ICANN to make a statement on the matter last month. While it is concerned about homograph spoofing in IDNs, the organisation said it "is equally concerned about the implementation of countermeasures that may unnecessarily restrict the use and availability of IDNs", for example having IDN support turned off by default.

Other vulnerabilities involve AFP Server, Bluetooth Setup Assistant Cyrus SASL, Mailman and other aspects of OS X, and could allow exposure of sensitive information, privilege escalation and denial of service, Apple said. The problems can all be fixed by installing the patch.