Core Security Technologies issued a security advisory for Microsoft Virtual PC software – calls out a proof of concept where virtual machine monitor allows memory pages above 2GB level to be read from or written to by user-space programs running within a guest operating system. Advisory explicitly calls into question the effectiveness of many of the security hardening features of Windows, including DEP, SafeSEH, and ASLR. “First and foremost, this advisory doesn’t affect security of Windows 7 systems directly. Security safeguards (DEP, ASLR, SafeSEH, etc.) that’re in place remain effective at helping protect users from malware on that system. In addition, Our Windows Server virtualization technology, Hyper-V, is alson’t affected by this advisory. Apps running inside a Hyper-V guest continue to benefit from these same security safeguards. Functionality described only affects guest OS running within a VPC environment. In practice, guest OS in a VPC environment is typically Windows XP as part of Windows XP Mode. Of the safeguards Core calls out, it should be noted that only DEP is available in XP SP3; XP doesn't contain ASLR. The net result? An attacker can only exploit a vulnerable app running "inside" guest VM on XP, rather than Win7! Customers who need XP Mode, should look to install only required subset of apps that need XP in order to function properly while planning to move those apps to Win7 in future,” explained Microsoft.