Hackers will often hit third-party service providers as a stepping stone toward more sensitive targets. Earlier this year, online marketer Epsilon Data Management was compromised, forcing dozens of companies, including J.P. Morgan, Verizon, and TiVo, to warn millions of customers that their email addresses had been stolen.

Many of the defaced sheriffs' websites had been restored by Sunday morning. The victims include sheriffs in Arkansas, Mississippi, and Missouri.

The hackers claim to have obtained passwords, contact information and social security numbers from the Missouri Sheriffs' Association's website, which remained offline Sunday.

The IDG News Service