A newly discovered flaw in a critical piece of Internet infrastructure software could put more than half the Internet’s e-mail servers at risk, researchers say. The flaw exists in Sendmail, a program that sorts and delivers most e-mail. A single message sent at a flawed e-mail server could allow an attacker to take control of the server, read its contents and use it to organize a massive denial of service attack. But officials are hopeful that a month’s work of secret efforts to shore up defenses against the flaw — which included informing top federal offices and foreign governments — will minimize its impact.
THE FLAW WAS ACTUALLY found in late December, but not revealed until today. That gave the Department of Homeland Security time to organize efforts that would protect against possible attacks, said Alan Paller, director of research at security firm The SANS Institute.
Because there are so many different flavors of Sendmail, twenty software vendors had to develop a variety of patches for the flaw. The flaw impacts principally Unix and Linux systems, as well as a limited number of Windows servers that run Sendmail — but it doesn’t affect desktop computers and won’t require action by typical consumers.
But estimates say between 50 and 75 percent of all the Internet’s e-mail is handled by the various versions of Sendmail, making the flaw particularly pervasive — even more than the flaws that led to the now-infamous Code Red and Slammer worms.