Mac OS X gets an unwelcome visitor

A new adware program silently installs on Mac OS X systems and opens web browser windows, according to F-Secure.

The program, dubbed iAdware by the Finnish security company, is possibly the first example of adware for Macs. It is especially interesting since it doesn't require administrative privileges to nestle itself on the computers, said F-Secure.

The F-Secure blog said: "We won't disclose the exact technique used here, it's a feature not a bug, but let's just say that installing a System Library shouldn't be allowed without prompting the user."

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The program is a proof-of-concept sent to F-Secure and it is not out targeting users on the internet.

According to the F-Secure blog: "In theory, this program could be silently installed to your user account and hooked to each application you use. This particular sample successfully launched the Mac's web browser when we used any of a number of applications."

Malicious software that targets Mac OS X systems is rare and has been limited largely to proof-of-concept code, instead of actual attacks. However, there are indications that hackers are increasingly targeting the Mac, which experts have said is not impervious to attacks.

For example, as part of a campaign called the Month of the Kernel Bugs, several new flaws have been disclosed in Apple software, the latest on Monday in the AppleTalk protocol. Last week, exploit code was released for another yet-to-be-fixed flaw in Mac OS X related to disk image structures.

Apple could not immediately be reached for comment.

Joris Evers writes for CNET News.com