The percentage of targeted attacks exploiting vulnerabilities in Adobe Reader is growing at a significant rate, outstripping Microsoft Word, Excel and PowerPoint, according to the latest figures from security firm F-Secure.

In a new blog posting, the firm urged users to patch a critical vulnerability in the popular software which was discovered last month and is being actively exploited in the wild.

"Our sample was submitted by a European financial organisation and the file name includes a reference to the G20," the blog posting explained.

"The exploit drops a downloader and attempts to make a connection to tiantian.ninth.biz. We detect this attack as Exploit:W32/PDFExploit.G. It doesn't surprise us to see this Adobe Reader vulnerability utilised so quickly."

According to F-Secure's research, targeted attacks exploiting Adobe Reader grew from around 49 per cent last year to over 60 per cent in the first two months of this year.

By comparison, Microsoft Word accounted for around 39 per cent of targeted attacks so far this year, slightly up from 34 per cent in 2009. Excel and PowerPoint attacks stood at around seven per cent.