Linux remains the most attacked online server operating system, according to a new report.

For the month of August, 67 percent of all overt digital attacks against online servers targeted Linux, reports mi2g, a digital risk assessment company based in London. The report also notes that Microsoft's Windows operating system received 23.2 percent of the attacks.

Mi2g notes that 12,892 Linux online servers running eBusiness and information sites were successfully breached in August, followed by 4,626 Windows servers.

Over the last 12 months, Linux remained the most attacked operating system online with 51 percent of all successful overt digital attacks, according to mi2g.

''The proliferation of Linux within the online server community coupled with inadequate knowledge of how to keep that environment secure when running vulnerable third-party applications is contributing to a consistently higher proportion of compromised Linux servers,'' says D.K. Matai, executive chairman of mi2g. ''Microsoft deserves credit for having reduced the proportion of successful online hacker attacks perpetrated against Windows servers.''

An overt digital attack generally is defined as an attack on a computer or digital machine that is known about and verifiable.

Overt digital attacks weren't as costly in August as in previous months. But despite that, August suffered tremendously under covert attacks and viruses.

The economic damage -- which mi2g measures in terms of lost productivity and recovery costs -- through overt digital attacks in August was below average and rang in at $707 million.

But mi2g reported earlier this month that August will go down as setting a new record for digital damage -- largely due to the virus attacks on the Windows operating system.

Thanks to the havoc that Sobig-F and the Blaster worms wreaked, August reportedly has gone down as the worst month in digital history for virus attacks. Last month, viruses, along with overt and covert hacker attacks, caused $32.8 billion in economic damages, according to a new report from mi2g, a digital risk assessment company based in London. Mi2g also notes that the Sobig virus alone accounted for $29.7 billion of economic damages worldwide.

Mi2g also reports that Sobig, which, like Blaster, attacked Microsoft systems, has become the most damaging virus on record, overtaking malicious rivals Klez, Love Bug and Yaha. The Klez worm has been pushed to second place on the infamous list, causing $13.9 billion worth of damage. The Love Bug is now in the third position, accounting for $8.75 billion in damages.