Lest readers think “catastrophic” is too exaggerated a description for the critical defect affecting an estimated two-thirds of the Internet’s Web servers, consider this: at the moment this article was being prepared, the so-called Heartbleed bug was exposing end-user passwords, the contents of confidential e-mails, and other sensitive data belonging to Yahoo Mail and almost certainly countless other services.
The two-year-old bug is the result of a mundane coding error in OpenSSL, the world’s most popular code library for implementing HTTPS encryption in websites, e-mail servers, and applications. The result of a missing bounds check in the source code, Heartbleed allows attackers to recover large chunks of private computer memory that handle OpenSSL processes. The leak is the digital equivalent of a grab bag that hackers can blindly reach into over and over simply by sending a series of commands to vulnerable servers. The returned contents could include something as banal as a time stamp, or it could return far more valuable assets such as authentication credentials or even the private key at the heart of a website’s entire cryptographic certificate.
Underscoring the urgency of the problem, a conservatively estimated two-thirds of Internet’s Web servers use OpenSSL to cryptographically prove their legitimacy and to protect passwords and other sensitive data from eavesdropping. Many more e-mail servers and end-user computers rely on OpenSSL to encrypt passwords, e-mail, instant messages and other sensitive data. OpenSSL developers have released version 1.0.1g that readers should install immediately on any vulnerable machines they maintain. But given the stakes and the time it takes to update millions of servers, the risks remain high.