This week Finnish security company F-Secure discovered that the file had been under their noses all along. Someone — the company assumes it was an employee of RSA or its parent firm, EMC — had uploaded the malware to an online virus scanning site back on March 19, a little over two weeks after RSA is believed to have been breached on March 3. The online scanner, VirusTotal, shares malware samples it receives with security vendors and malware researchers.
RSA had already revealed that it had been breached after attackers sent two different targeted phishing e-mails to four workers at its parent company EMC. The e-mails contained a malicious attachment that was identified in the subject line as “2011 Recruitment plan.xls.”
None of the recipients were people who would normally be considered high-profile or high-value targets, such as an executive or an IT administrator with special network privileges. But that didn’t matter. When one of the four recipients clicked on the attachment, the attachment used a zero-day exploit targeting a vulnerability in Adobe Flash to drop another malicious file — a backdoor — onto the recipient’s desktop computer. This gave the attackers a foothold to burrow farther into the network and gain the access they needed.