A zero-day for Windows 7 back in July of this year also bypassed Windows UAC.

Once again a serious zero-day has hit Windows, this time an unpatched vulnerability in the Kernel. So far it only seems to be a local exploit, for full devastating effect hackers will need to combine this with a remote zero-day to get access to the machine and then elevate their permissions and bypass UAC with this.

Microsoft is investigating reports of an unpatched vulnerability in the Windows kernel that could be used by attackers to sidestep an important operating system security measure.

One security firm dubbed the bug a potential “nightmare,” but Microsoft downplayed the threat by reminding users that hackers would need a second exploit to launch remote attacks.

The exploit was disclosed Wednesday — the same day proof-of-concept code went public — and lets attackers bypass the User Account Control (UAC) feature in Windows Vista and Windows 7. UAC, which was frequently panned when Vista debuted in 2007, displays prompts that users must read and react to. It was designed to make silent malware installation impossible, or at least more difficult.

“Microsoft is aware of the public posting of details of an elevation of privilege vulnerability that may reside in the Windows kernel,” said Jerry Bryant, a group manager with the Microsoft Security Response Center, in an e-mail. “We will continue to investigate the issue and, when done, we will take appropriate action.”

The bug is in the “win32k.sys” file, a part of the kernel, and exists in all versions of Windows, including XP, Vista, Server 2003, Windows 7 and Server 2008, said Sophos researcher Chet Wisniewski in a Thursday blog post.

Microsoft is aware of the flaw but has not yet issued a statement as to when they will be patching this, I’d imagine given their past that will wait for the next Patch Tuesday before pushing the patch out. And plus the fact it’s a kernel bug it, it may take a little more time to fix.

The security companies seem to be taking this one quite seriously as the publicly-released code is confirmed working across multiple versions of Windows.

There is a very slight chance that Microsoft might push an Out-of-band-patch for this, but I find it unlikely as it’s not a remote vulnerability.

Several security companies, including Sophos and Vupen, have confirmed the vulnerability and reported that the publicly-released attack code works on systems running Vista, Windows 7 and Server 2008.

Hackers cannot use the exploit to remotely compromise a PC, however, as it requires local access, a fact that Microsoft stressed. “Because this is a local elevation-of-privilege issue, it requires attackers to be already able to execute code on a targeted machine,” said Bryant.

“On its own, this bug does not allow remote code execution, but does enable non-administrator accounts to execute code as if they were an administrator,” added Wisniewski.

Although many Windows XP users, especially consumers and those in very small businesses, run the OS via administrator accounts, Microsoft added UAC to Vista and later operating systems as one way to limit user privileges, and thus malware’s access to the PC.

Attackers would have to combine the exploit with other malicious code that takes advantage of another vulnerability on the machine — not necessarily one in Windows, but in any commonly-installed application, such as Adobe Reader, for example — to hijack a PC and bypass UAC.

“This exploit allows malware that has already been dropped on the system to bypass [UAC] and get the full control of the system,” said Prevx researcher Marco Giuliani in an entry on that security company’s blog Thursday.

Prevx reported the vulnerability to Microsoft earlier in the week.

Microsoft has changed the way UAC functions before when it was demonstrated that it could be easily bypassed. The next patch cycle is due on Tuesday, Dec. 14 – which thankfully isn’t too long. I’d be expecting a kernel patch for this issue by then.

There is more info about the issue here:

Sophos – New Windows zero-day flaw bypasses UAC
Prevx – Windows 0-day exploit: Q&A session

Source: Network World

There have been a few stories about Windows 7, even one about Windows 7 UAC before and now it’s officially on sale I’d expect there to be many more.

As always malware and mass infections is a numbers game so the bad guys will always target the most popular and prolific operating systems to increase their chances of widespread infections.

For me personally UAC in Windows Vista was simply a pain in the ass, so much so I just turned it off completely as did most people rendering it completely ineffective. They seem to have toned it down in Windows 7 to make it less invasive and perhaps as a byproduct have made it less effective.

A researcher at Sophos reports putting Windows 7′s User Account Control feature to the test and finding the technology failed to block numerous pieces of malware. Microsoft, however, stresses that UAC is only one part of Windows 7′s security.

A researcher at Sophos called the UAC feature in Windows 7 ineffective after numerous pieces of malware snuck by the technology in a test.

Microsoft first introduced User Account Control in Windows Vista to improve security. After some users complained the number of alerts it generated were annoying, the company pledged to cut down on the number of prompts in Windows 7. The move however has raised concerns in the security community, and Sophos Senior Security Adviser Chester Wisniewski said his test proves Microsoft took it a step too far.

Wisniewski wrote on his blog Nov. 3 that seven of the 10 pieces of malware he tested ran with the default AUC enabled in Windows 7 without generating any prompts. As part of the test, no antivirus software was installed on the system. Two of the malware samples did not work in Windows 7; of the remaining eight, only one generated a prompt, and that one still would have been installed had the user clicked yes, Wisniewski told eWEEK.

I’d imagine it only throws an alert if the software being installed tries to modify system files or place itself in system directories (c:/windows etc).

That would make sense to me, and yes it would make it ineffective against malware and even more ineffective when the bad guys work out how it functions and adapt to that.

Nothing much new here though is it, run anything on Windows XP and you’ll get no warnings..so just be vigilant. I’d rather Microsoft try an educate people on good security practice rather than trying to implement half-arsed technical measures to protect against wetware ignorance.

When asked about the test, Microsoft officials pointed to the other features of Windows 7 that have improved security.

“Windows 7 is built upon the security platform of Windows Vista, which included a defense-in-depth approach to help protect customers from malware; this includes features like Security Development Lifecycle (SDL), User Account Control (UAC), Kernel Patch Protection, Windows Service Hardening, Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP),” a spokesperson said.

“Windows 7 retains all of the development processes, including going through the Security Development Lifecycle, and technologies that made Windows Vista the most secure Windows operating system ever released,” the spokesperson added. “Coupled with Internet Explorer 8—which includes added malware protection with its SmartScreen Filter—and Microsoft Security Essentials, Windows 7 provides flexible security protection against malware and intrusions.”.

All the above technologies are great and they do help a LOT when it comes to exploitation of vulnerabilities and trying to execute shell-code. But that’s not the biggest threat, the biggest threat is idiot users installing malware ‘by accident‘ on their own computers.

So yes, however obvious it may seem to us – you still need to install Anti-virus software on Windows 7.

Source: eWeek