A hacker's claim that he compromised the successor to President Obama's campaign Web site appears to be a hoax, according to information that surfaced since the matter came to light early Monday. The kerfuffle started when a hacker and blogger with a history of posting evidence of security vulnerabilities in popular and high-traffic Web sites published evidence indicating that poor security at barackobama.com had exposed internal databases at the site. The hacker, identified only as "Unu," claimed that a security flaw in barackobama.com allows anyone to view the user names and passwords needed to administer the site. With that access,...