Posts Tagged: DEP


5
Nov 13

Microsoft Warns of Zero-Day Attack on Office

Microsoft warned today that attackers are targeting a previously unknown security vulnerability in some versions of Microsoft Office and Windows. The company also has shipped an interim “Fix-It” tool to blunt attacks on the flaw until it has time to develop and release a more comprehensive patch.

crackedwinIn a post on its Technet blog, Microsoft said the attacks observed so far against the vulnerability have been “carefully carried out against selected computers, largely in the Middle East and South Asia.” It added that the exploit needs some user interaction because it arrives disguised as an email that entices potential victims to open a specially crafted Microsoft Word attachment.

The exploit attacks an unpatched security flaw in the way some older versions of Office and Windows process graphical images. According to Microsoft, the exploit combines multiple techniques to bypass exploit mitigation techniques such as data execution prevention (DEP) and address space layout randomization (ASLR). The company says this exploit will not affect Office 2013, but will affect older versions such as Office 2003 and Office 2007.

“Due to the way Office 2010 uses the vulnerable graphic library, it is only affected only when running on older platforms such as Windows XP or Windows Server 2003, but it is not affected when running on newer Windows families (7, 8 and 8.1),” Microsoft wrote.

affectednot

Microsoft’s latest Fix-It tool should help blunt attacks on this vulnerability. Also, while this particular exploit does try to evade DEP and ASLR protections, it’s probably as good a time as any to remind readers about Microsoft EMET, a free tool that can increase the security of third party applications that run on top of Windows.

Interestingly, news of the exploit surfaced less than 48 hours after Microsoft announced it would expand its $100,000 bug bounty program for researchers who can find and report novel exploitation techniques for evading Windows’ built-in defenses.


18
Jun 13

Windows Security 101: EMET 4.0

Several years ago, Microsoft released the Enhanced Mitigation Experience Toolkit (EMET), a free tool that can help Windows users beef up the security of third-party applications. This week, Microsoft debuted EMET 4.0, which includes some important new security protections and compatibility fixes for this unobtrusive but effective security tool.

EMET's main window.

The main window of EMET 4.0

First, a quick overview of what EMET does. EMET allows users to force applications to use several key security defenses built into Windows — including Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP). Put very simply, DEP is designed to make it harder to exploit security vulnerabilities on Windows, and ASLR makes it more difficult for exploits and malware to find the specific places in a system’s memory that they need to do their dirty work.

EMET can force a non-Microsoft application to perform ASLR on every component it loads, whether the program wants it or not. Please note that before you install EMET, you’ll need to have Microsoft’s .NET Framwork 4 platform installed. And while EMET does work on Windows XP (Service Pack 3 only), XP users cannot take advantage of mandatory ASLR and a few other notable protections included in this tool.

However, EMET includes several important security features that can help fortify third-party applications on XP. Namely, its “Structured Exception Handler Overwrite Protection,” or SEHOP protection, which guards against the most common technique for exploiting stack overflows on Windows. Microsoft says this mitigation has shipped with Windows ever since Windows Vista Service Pack 1.

In addition to a revised user interface, EMET 4.0 includes a handful of new features that were bundled with the 3.5 tech preview version, such as novel methods of blocking an exploit technique called return-oriented programming (ROP). Attackers can leverage ROP to bypass DEP protections by using snippets of code that are already present in the targeted application.  

One of the much-hyped new capabilities of EMET 4.0 is its “certificate trust” feature, which is designed to block so-called “man-in-the-middle” attacks that leverage counterfeit SSL certificates in the browser. The past few years saw several attacks that impersonated Webmail providers and other top Internet destinations using fraudulent digital certificates obtained by certificate authorities, including Comodo, DigitNotar and Turktrust. This feature is a nice idea, but it seems somewhat clunky to implement, and only works to protect users who browse the Web with Internet Explorer. For tips on configuring and using this feature of EMET, check out this post.

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18
Sep 12

Internet Explorer Users: Please Read This

Microsoft is urging Windows users who browse the Web with Internet Explorer to use a free tool called EMET to block attacks against a newly-discovered and unpatched critical security hole in IE versions 7, 8 and 9. But some experts say that advice falls short, and that users can better protect themselves by surfing with an alternative browser until Microsoft issues a proper patch for the vulnerability.

The application page of EMET.

EMET, short for the Enhanced Mitigation Experience Toolkit, is a tool that can help Windows users beef up the security of commonly used applications, whether they are made by a third-party vendor or by Microsoft. EMET allows users to force applications to use one or both of two key security defenses built into Windows Vista and Windows 7 — Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP).

Put very simply, DEP is designed to make it harder to exploit security vulnerabilities on Windows, and ASLR makes it more difficult for exploits and malware to find the specific places in a system’s memory that they need to do their dirty work.

Before I get into the how-tos on EMET, a few caveats. EMET is a great layer of security that Windows users can and should use to enhance the security of applications. But EMET may not block the exploit code now publicly available through the Metasploit framework. In fact, Tod Beardlsey, an engineering manager with Rapid7, the security firm that manages Metasploit, told The Associated Press that EMET does not appear to be completely effective against this exploit.

I asked Metasploit founder HD Moore what he thought was the best way to block this exploit, and he pointed out that the exploit available through Metasploit requires the presence of Java on the host machine in order to execute properly on IE 8/9 on Windows 7 and Vista systems (the exploit works fine without Java against IE7 on XP/Vista and IE8 on XP). Obviously, while the lack of Java on a Windows machine may not prevent other exploits against this flaw, it is a great first start. I have consistently urged computer users of all stripes to uninstall Java if they have no specific use for it.

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9
Jul 12

How to Break Into Security, Grossman Edition

I recently began publishing a series of advice columns for people who are interested in learning more about security as a craft or profession. For the third installment in this series, I interviewed Jeremiah Grossman, chief technology officer of WhiteHat Security, a Web application security firm.

A frequent speaker on a broad range of security topics, Grossman stressed the importance of coding, networking, and getting your hands dirty (in a clean way, of course).

BK: How did you get started in computer security?

Grossman: For me it was…I could hack stuff and I did it in my spare time and someone offered me a job — which was Yahoo. But before that, I was just a UNIX admin. I was thinking about this question a lot, and what occurred to me is that I don’t know too many people in infosec who chose infosec as a career. Most of the people who I know in this field didn’t go to college to be infosec pros, it just kind of happened. They followed opportunity.

BK: You might have seen that the last two experts I asked had somewhat different opinions on this question, but how important is it that someone interested in this field know how to code?

Grossman: It’s tough to give solid advice without knowing more about a person. For instance, are they interested in network security or application security? You can get by in IDS and firewall world and system patching without knowing any code; it’s fairly automated stuff from the product side. But with application security, it is absolutely mandatory that you know how to code and that you know software. So with Cisco gear, it’s much different from the work you do with Adobe software security. Infosec is a really big space, and you’re going to have to pick your niche, because no one is going to be able to bridge those gaps, at least effectively.

BK: So would you say hands-on experience is more important that formal security education and certifications?

Grossman: The question is are people being hired into entry level security positions straight out of school? I think somewhat, but that’s probably still pretty rare. There’s hardly anyone coming out of school with just computer security degrees. There are some, but we’re probably talking in the hundreds. I think the universities are just now within the last 3-5 years getting masters in computer security sciences off the ground. But there are not a lot of students in them.

BK:  What do you think is the most important qualification to be successful in the security space, regardless of a person’s background and experience level?

Grossman: The ones who can code almost always [fare] better. Infosec is about scalability, and application security is about scalability. And if you can understand code, you have a better likelihood of being able to understand how to scale your solution. On the defense side, we’re out-manned and outgunned constantly. It’s “us” versus “them,” and I don’t know how many of “them,” there are, but there’s going to be too few of “us “at all times.  So whatever your solution is or design criteria, you’re going to have to scale it. For instance, you can imagine Facebook…I’m not sure many security people they have, but…it’s going to be a tiny fraction of a percent of their user base, so they’re going to have to figure out how to scale their solutions so they can protect all those users.

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9
May 11

Security Group Claims to Have Subverted Google Chrome’s Sandbox

A French security research firm boasted today that it has discovered a two-step process for defeating Google Chrome‘s sandbox, the security technology designed to protect the browser from being compromised by previously unknown security flaws. Experts say the discovery, if true, marks the first time hackers have figured out a way around the vaunted security layer, and almost certainly will encourage attackers to devise similar methods of subverting this technology in Chrome and other widely used software.

In an advisory released today, VUPEN Security said: “We are (un)happy to announce that we have official Pwnd Google Chrome and its sandbox.” The post includes a video showing the exploitation of what VUPEN claims is a previously undocumented security hole in Chrome v.11.0.696.65 on Microsoft Windows 7 SP1 (x64).

“While Chrome has one of the most secure sandboxes and has always survived the Pwn2Own contest during the last three years, we have now uncovered a reliable way to execute arbitrary code on any installation of Chrome despite its sandbox, ASLR and DEP,” the advisory notes. ASLR and DEP are two of the key security defenses built into Windows Vista and Windows 7

Google spokesman Jay Nancarrow said the company was unable to verify VUPEN’s claims, because VUPEN hadn’t shared any information about their findings. “Should any modifications become necessary, users will be automatically updated to the latest version of Chrome,” Nancarrow wrote in an email to KrebsOnSecurity.

Chaouki Bekar, VUPEN’s CEO and head of research, confirmed that the company had no plans to share any details about their findings with Google, nor was it aware of any steps users could take to mitigate the threat from this attack.

“No, we did not alert Google as we only share our vulnerability research with our Government customers for defensive and offensive security,” Bekar wrote in response to an emailed request for comment. “Unfortunately, we are not aware of any mitigation to protect against these vulnerabilities.”

Jeremiah Grossman, a Web application security expert and chief technology officer for the security consultancy WhiteHat Security, called the news “quite serious.”

“We have governments competing for 0days, and we’re not even sure who the buyers are, maybe the US government didn’t get the 0day,” Grossman said “One way or the other, consumers are unprotected from an 0day we can’t really verify but probably exists. I think that’s quite serious.”

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23
Dec 10

Exploit Published for New Internet Explorer Flaw

Hackers have released exploit code that can be used to compromise Windows PCs through a previously unknown security flaw present in all versions Internet Explorer, Microsoft warned today.

Dave Forstrom, director of trustworthy computing at Microsoft, said although the software giant is not aware of any attacks wielding this flaw against Windows users, “given the public disclosure of this vulnerability, the likelihood of criminals using this information to actively attack our customers may increase.”

Microsoft’s security advisory says the problem has to do with the way IE handles CSS style sheets. A posting on Microsoft’s Security Research & Defense blog notes that the Metasploit Project recently published an exploit for this flaw that evades two of the key security defenses built into Windows Vista and Windows 7 — Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP).

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