Microsoft has been steadily adding memory-protection technologies such as ASLR and DEP to its products over the last few years. These technologies are mitigations, not absolute defenses against exploitation, a researcher says. Microsoft has acknowledged the limitations of DEP from the beginning, and says it is simply one of several tools that can help prevent memory corruption attacks. Even with DEP and ASLR enabled, it s still possible to exploit vulnerabilities in the most recent versions of IE and Windows.
Source: https://threatpost.com/memory-protections-advance-exploits-stay-step-ahead-030810/73642/