Preventing today's top vulnerability

This article discusses the top vulnerability in Linux/UNIX systems: buffer overflows. This article first explains what buffer overflows are and why they're both so common and so dangerous. It then discusses the new Linux and UNIX methods for broadly countering them -- and why these methods are not enough. It then shows various ways to counter buffer overflows in C/C++ programs, both statically-sized approaches (such as the standard C library and OpenBSD/strlcpy solution) and dynamically-sized solutions, as well as some tools to help you. Finally, the article closes with some predictions on the future of buffer overflow vulnerabilities.

In November 1988, many organizations had to cut themselves off from the Internet because of the "Morris worm," which was a program written by 23-year-old Robert Tappan Morris to attack VAX and Sun machines. By some estimates, this program took down 10% of the entire Internet. In July 2001, another worm named "Code Red" eventually exploited over 300,000 computers worldwide running Microsoft's IIS Web Server. In January 2003, the "Slammer" (also known as "Sapphire") worm exploited a vulnerability in Microsoft SQL Server 2000 software, disabling parts of the Internet in South Korea and Japan, disrupting Finnish phone service, and slowing many U.S. airline reservation systems, credit card networks, and automatic teller machines. All of these attacks -- and many others -- exploited a vulnerability called a buffer overflow.

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