Michael Howard (of the Secure Development Lifecycle team at Microsoft) has posted a detailed analysis of the recent MS07-017 security vulnerability, and the lessons learned from examining the code responsible for the vulnerability.  Great read.

A core tenet of the SDL is to take and incorporate lessons learned when we issue a security update, and there is a great deal to learn from the recent animated cursor bug, MS07-017, so I want to spend a few minutes to go over some of the things we have learned from this bug.

First of all, this code is pretty old; is in Windows 2000, and predates the SDL. The SDL has parts (i.e., design review, threat modeling, testing, and security push) that focus on the product as a whole, and parts (i.e., code review and use of tools) that are focused on code. In the Windows Vista process, we banned certain APIs, like strcpy and strncpy, and changed well over 140,000 calls to use safer calls. memcpy wasn’t on that list. We also built in a lot of defense-in-depth measures because we know that the SDL can’t catch everything. Let’s start by looking at some of the defense-in-depth measures we have in place that didn’t stop the threat:

Read the rest of the post here.