Spammers Mounting Directory Harvest Attacks Against Corporate Email at Record Levels

March 2, 2005
Email security provider says February levels bested previous records

REDWOOD CITY, Calif. -- Postini, the industry's leading provider of email security and management for the enterprise, today announced that directory harvest attacks (DHAs) by spammers against corporate email reached record levels in February. Postini also reported that unwanted email has remained virtually unchanged at 88 percent while only 12 percent of all email is legitimate. Postini's findings are based on the 14.8 billion messages it processed in February.

DHAs are brute force attempts by spammers to connect to a business e-mail server and guess at addresses until finding valid emails from corporate directories. Those addresses are then harvested for use in later spam campaigns.

"February was the worst month ever for DHAs," said Andrew Lochart, director of product marketing for Postini. "In fact, the five worst days ever recorded by Postini were in February. The average Postini customer was attacked 224 times per day, with each attack comprising 166 invalid message delivery attempts. That total of 37,184 invalid delivery attempts per day could have crippled customer email servers if left unchecked." The company protected its customers from over 25 million DHAs that attempted 4.2 billion invalid delivery attempts during the month.

Despite the rash of new viruses that were detected in February, the percentage of email infected with a virus actually fell slightly in February from 0.9 percent to 0.7 percent. The top ten viruses were:

Virus Name				 Quantity Detected
1.  netsky				  17,728,871
2.  mime				   8,626,995
3.  bagle				   7,803,583
4.  zafi				   4,834,140
5.  sober				   3,098,191
6.  mydoom				   2,028,145
7.  bankfraud				   1,964,803
8.  phish-bankfraud			   1,288,160
9.  lovgate				     988,250
10. new malware-e			     694,528

Postini's managed services model uses patented preEMPT(TM) preemptive email protection technology to protect enterprise email at the perimeter, stopping spam and viruses before they enter the network. The solution handles enterprise email system security and management, offering spam and virus filtering, content and policy management, disaster recovery, industry specific content filtering, and protection from email attacks such as directory harvest attacks and email denial of service attacks. Postini processes approximately 3 billion messages each week through its array of distributed data centers, five times more than any other email security services provider, making Postini the fourth-largest email system in the world.

Postini's Email Stat Track is available to users at and provides the most up-to-date statistics on the latest viruses, spam and DHA attacks.