Feeds

Researchers penetrate last bastion of Windows security

With a little help from Adobe

Internet Security Threat Report 2014

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.

By using the JIT-spraying technique, however, Blazakis was able to bypass the measures and cause IE 8 to open the Windows calculator, proof that he could exploit the Adobe bug to execute code of his choice.

Similarly, a potent flaw used to pierce the defenses of Google and other large companies was present in all recent versions of IE, but only exploitable on version 6, which was released in 2001.

But using a similar JIT-spraying attack, researchers at Miami-based security firm Immunity have figured out how to reliably exploit the bug in IE 8 running on Windows 7. The attack was released Wednesday to the early updates section for Immunity's Canvas tool sold to penetration testers.

Nicolas Pouvesle, the Immunity senior security researcher who developed the exploit, said overcoming the protections wasn't easy. First, he had to figure out how to locate his malicious shellcode in Windows 7 memory. Then he had to figure out how to overcome DEP, which prevents data loaded into memory from being executed.

"ASLR and DEP in IE 8 on Windows 7 provides a really good protection against these kinds of exploits," he said. "It took us quite some time to put everything together."

After using Flash to spray "lots of big Flash files" into memory, Pouvesle overcame DEP by converting action script into machine code and lacing it with camouflaged shellcode.

This isn't the first time attackers have figured out how to bypass memory protections built into Microsoft software. After a technique known as heap spraying came into vogue, Microsoft added protections to thwart it in IE 8, Pouvesle said. This time around, it's not at all clear Microsoft will be able to prevent the newfangled attacks so easily.

"A change in the memory allocator could prevent" JIT-spraying," he said. "That is, I think, way too complex to do. I don't think we're going to see that happen anytime soon." ®

Internet Security Threat Report 2014

More from The Register

next story
George Clooney, WikiLeaks' lawyer wife hand out burner phones to wedding guests
Day 4: 'News'-papers STILL rammed with Clooney nuptials
Shellshock: 'Larger scale attack' on its way, warn securo-bods
Not just web servers under threat - though TENS of THOUSANDS have been hit
Apple's new iPhone 6 vulnerable to last year's TouchID fingerprint hack
But unsophisticated thieves need not attempt this trick
PEAK IPV4? Global IPv6 traffic is growing, DDoS dying, says Akamai
First time the cache network has seen drop in use of 32-bit-wide IP addresses
Oracle SHELLSHOCKER - data titan lists unpatchables
Database kingpin lists 32 products that can't be patched (yet) as GNU fixes second vuln
Researchers tell black hats: 'YOU'RE SOOO PREDICTABLE'
Want to register that domain? We're way ahead of you.
Stunned by Shellshock Bash bug? Patch all you can – or be punished
UK data watchdog rolls up its sleeves, polishes truncheon
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.