UPDATE -- link to interesting article from Channel Insider.

Back in March, we reported on a massive and sophisticated attack on RSA Security's well-known SecurID tokens, used by millions of corporate workers to access sensitive corporate networks.  Yesterday, the security unit of EMC Corp. posted a letter to customers on its website, acknowledging for the first time that intruders had breached its systems at defense contractor Lockheed Martin Corp.   In an interview with the Wall Street Journal [registration may be required], RSA Chairman Art Coviello said that the company is offering to replace SecurID tokens "for virtually every customer we have."

Reuters first reported on a "tenacious" external cyberattack on the Lockheed Martin systems and those of several other US defense contractors on May 27.    The Reuters piece first raised the spectre that the stolen RSA tokens were at the root of the attack:

The hackers learned how to copy the security keys with data stolen from RSA during a sophisticated attack that EMC disclosed in March, according to the source.

EMC declined to comment on the matter, as did executives at major defense contractors.

Rick Moy, president of NSS Labs, an information security company, said the original attack on RSA was likely targeted at its customers, including military, financial, governmental and other organizations with critical intellectual property.

The "security press" has been also ruminating for some days now about whether the compromise of the RSA security tokens was actually at the core of the Lockheed Martin breach.  Some good reading:  New York Times on May 27,  The Raw Story on May 27, Reuters on May 27, InfoSecurity on May 30.