Hackers broke into an online comic strip syndication service Thursday, embedding malicious code that sought to exploit a newly discovered security flaw in Adobe Reader and Acrobat, Security Fix has learned. On Monday, Adobe Systems Inc. said it was investigating reports that criminals were attacking Internet users via a previously unknown security flaw in its Adobe Reader and Acrobat software. Experts warned that the flaw could be used to foist software on unsuspecting users who visit a hacked or booby-trapped Web site. Albany, N.Y.-based Hearst publication Timesunion.com now reports that on Thursday readers of its comics section began complaining of being prompted to download malicious software. In an update posted to its site, Timesunion.com said the attack took advantage of the recently disclosed Adobe flaw. The news outlet said it had traced the attack back to a problem at King Features, which serves comics on its Web site, and that