Monster.com and Monster-powered government job site USAJOBS are the victims of a large-scale data breach of job seeker information. See this article for details. If you have accounts on these sites, read the article for advice on how to take precautions.
Best suggestion? Remove your resume and profile from Monster completely. Being the largest career site on the internet, Monster is unfortunately also the biggest target. Since anyone with a credit card can view resumes on Monster, and Monster has a long history of losing job seeker data, having your resume only on ClearanceJobs.com makes sense.