Can a credit card company attach your bank account when the only income in the account comes from Social Security checks?

No. All SS benefits are 100% exempt from creditor action under federal and state statutes. Likewise workman's compensation insurance, disbility insurance, etc. Credit card companies in themselves cannot levy, garnish, or impede an individual's property. This can only be done by due process through the court of the person's resident state. The exception is a "set off" that can be used by a bank under specific circumstances. But this would NOT apply to SS benefits