As an epidemic of computer hacking incidents targeting companies and government agencies has raised computer security concerns across the board, one particular attack on a computer security firm has upped the ante in the battle between hackers and companies who must protect the sensitive data of customers, partners, and employees.

In March, Art Coviello, executive chairman of RSA, the security division of storage provider EMC Corp., posted a letter online to RSA customers, acknowledging that RSA had discovered an attack by hackers. The company is not saying how close it is to identifying any suspects in the attacks.

The attack on ...