Sept. 19 — A computer security researcher was able to edit and alter wire stories posted on Yahoo.com"s news pages this week, according to SecurityFocus.com. The researcher rewrote a story, subtly changing some facts and attributing faked comments to President George W. Bush. According to SecurityFocus.com, the researcher had access to Yahoo"s publishing tools for about three weeks, but Yahoo has since closed the security hole. Still, the incident makes real a threat that has been imagined for some time — that a determined hacker might be able to influence millions of readers by breaking into a popular source of news on the Internet and secretly changing its content.