Researchers penetrate last bastion of Windows security
Security researchers have defeated vulnerability protections baked into the latest versions of Internet Explorer, demonstrating that it’s possible to poke holes in a safety net that’s widely relied on to keep end users safe from drive-by exploits.
By exploiting weaknesses in Adobe Systems’ Flash Player, researchers have devised two separate attacks that bypass mitigations Microsoft put into IE 7 and 8. Known as ASLR, or address space layout randomization, and DEP, or data execution prevention, the technologies are designed to lessen the severity of bugs by making it hard for them to cause the execution of malicious code.
Both techniques wield the so-called just-in-time compiler in Flash so that a computer’s memory is blanketed with large chunks of identical shellcode. The “JIT-spray” allows attackers to overcome ASLR, which normally thwarts execution by picking a different memory location to load system components each time an operating system is started.
“With this JIT-spray, it works fairly reliably, so at least nine out of 10 times you’ll guess the right position,” said Dionysus Blazakis, a researcher who is demonstrating one of the attacks on Wednesday at the Black Hat security conference in Washington, DC. “The compilers do this optimizing, so it wasn’t just a given that this was possible.”
The attacks are more than a mere academic exercise because ASLR and DEP have been some of the only defenses preventing lethal exploits of buffer overflows and other bugs in software running on Windows PCs. Last month’s unusually advanced attacks on Adobe’s Reader application didn’t work on IE 8, thanks to the protections.
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