Microsoft Finds (Random) Way to Secure VistaBy Ryan Naraine | Posted 05-30-2006
A security feature used in the open-source world is now helping to harden Windows Vista against buffer overrun exploits.
Microsoft has quietly fitted the feature, called ALSR (Address Space Layout Randomization) in Windows Vista Beta 2 as part of a larger plan to make it more difficult to automate attacks against the operating system.
"Not only is it in Beta 2, it's on by default too," said Michael Howard, senior security program manager at Microsoft in a blog entry announcing the news.
"We added ASLR pretty late in the game, but we decided that adding it to beta 2 and enabling it by default was important so we can understand how well it performs in the field," Howard said.
Howard, who wrote the book on Microsoft's highly-touted SDL (Security Development Lifecycle), stressed that ASLR is not a panacea or a replacement for insecure code but said it could serve as a "useful defense" against malware attacks when used in conjunction with other technologies.
Several open-source security systems OpenBSD, PaX and Exec Shield already implement ASLR, which is described as a security feature that randomly arranges the positions of key data areas to prevent malicious hackers from predicting target addresses.
"[It] is a useful defense because it makes Windows systems look "different" to malware, making automated attacks harder," Howard said.
"In short, when you boot a Windows Vista Beta 2 computer, we load system code into different locations in memory. This helps defeat a well-understood attack called 'return-to-libc', where exploit code attempts to call a system function," Howard explained.
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