My favorite talk, as expected, was the Sotirov/Dowd talk on How To Impress Girls With Browser Memory Protection Bypasses. The attack is a conceptually simple, yet completely reliable technique for exploiting vulnerabilities in web browsers. Of course, the media has sensationalized the impact of their findings, but ultimately, this is still significant as far as browser-based exploits are concerned. It’s worth mentioning that part of the technique allowing them to load a .NET DLL at an arbitrary location under Vista was reliant on an implementation bug wherein the OS disables ASLR if the version in the .NET COR header was below a certain value. However, the address space spraying and stack spraying techniques are likely to be extended to other platforms utilizing similar memory protection mechanisms.

As for the girls? I can report first-hand that the ladies at TAO on Wednesday night were hanging on Alex’s every word. They were particularly impressed when he whipped out the laptop for a live demo. Unfortunately, none of the dozen iPhone owners in the immediate vicinity thought to snap a picture (too busy Twittering). Oh well.

I also enjoyed Hovav Shacham’s talk on return-oriented programming. Simply put, he described a generalization of the return-to-libc shellcode approach with the intent to demonstrate that one could achieve Turing-complete computation using “found code” in process images. By chaining together series of mini-computations ending in return (RET) instructions, it was possible to build higher-level programming constructs such as branches and loops. The nature of the x86 instruction set provides some flexibility because instructions are interpreted differently depending on how you align the instruction pointer (i.e. the old shellcode trick of searching the process image for any JMP EBX instruction and using that as your EIP). In RISC architectures such as SPARC, however, you don’t have that luxury; if your %pc isn’t aligned properly you get a bus error. So it was quite interesting to see that they were able to extend the concept to RISC. The practicality of the attack technique is limited by the fact that the shellcode is tuned to a particular binary image — if the shellcode was built using instructions extrapolated from glibc 2.3.5, it won’t work for a system running glibc 2.4.

I thought Scott Stender’s talk on Concurrency Attacks in Web Applications was interesting as well. In a nutshell, spewing thousands of simultaneous requests at web application transactions that are not thread-safe can create interesting problems. In the presentation, Scott ran his demo against a VM running on the attack machine. I found myself wondering how effective the same attack would be over the Internet — would it be significantly less reliable (or not at all)? Race conditions are generally easier to exploit locally than remotely due to more predictable execution conditions. Certainly this is an under-tested vulnerability class though.

One presentation I wasn’t able to attend but want to follow up on is Nate McFeters, John Heasman, and Rob Carter’s talk which discussed the GIFAR attack I’ve been hearing so much about lately. The gist is that you can create a file that is both a valid GIF and a valid JAR, then use some Java applet tricks to initiate HTTP requests on behalf of the victim.

Finally, the Pwnie Awards didn’t fail to disappoint. Drama ensued over the Most Overhyped award, but at least this year some of the winners showed up to claim their awards! Halvar rapping Symantec lyrics was also quite memorable.

All in all, a fun and informative week, but as usual, I was relieved to get the hell out of Vegas and head home on Friday morning.

P.S. For a much more entertaining BlackHat/Defcon Recap, read Jennifer Jabbusch’s account of the week’s events. It’s my favorite one so far!

My favorite talk, as expected, was the Sotirov/Dowd talk on How To Impress Girls With Browser Memory Protection Bypasses. The attack is a conceptually simple, yet completely reliable technique for exploiting vulnerabilities in web browsers. Of course, the media has sensationalized the impact of their findings, but ultimately, this is still significant as far as browser-based exploits are concerned (here is a more accurate report). It’s worth mentioning that part of the technique allowing them to load a .NET DLL at an arbitrary location under Vista was reliant on an implementation bug wherein the OS disables ASLR if the version in the .NET COR header was below a certain value. However, the address space spraying and stack spraying techniques are likely to be extended to other platforms utilizing similar memory protection mechanisms.

As for the girls? I can report first-hand that the ladies at TAO on Wednesday night were hanging on Alex’s every word. They were particularly impressed when he whipped out the laptop for a live demo. Unfortunately, none of the dozen iPhone owners in the immediate vicinity thought to snap a picture (too busy Twittering). Oh well.

I also enjoyed Hovav Shacham’s talk on return-oriented programming. Simply put, he described a generalization of the return-to-libc shellcode approach with the intent to demonstrate that one could achieve Turing-complete computation using “found code” in process images. By chaining together series of mini-computations ending in return (RET) instructions, it was possible to build higher-level programming constructs such as branches and loops. The nature of the x86 instruction set provides some flexibility because instructions are interpreted differently depending on how you align the instruction pointer (i.e. the old shellcode trick of searching the process image for any JMP EBX instruction and using that as your EIP). In RISC architectures such as SPARC, however, you don’t have that luxury; if your %pc isn’t aligned properly you get a bus error. So it was quite interesting to see that they were able to extend the concept to RISC. The practicality of the attack technique is limited by the fact that the shellcode is tuned to a particular binary image — if the shellcode was built using instructions extrapolated from glibc 2.3.5, it won’t work for a system running glibc 2.4.

I thought Scott Stender’s talk on Concurrency Attacks in Web Applications was interesting as well. In a nutshell, spewing thousands of simultaneous requests at web application transactions that are not thread-safe can create interesting problems. In the presentation, Scott ran his demo against a VM running on the attack machine. I found myself wondering how effective the same attack would be over the Internet — would it be significantly less reliable (or not at all)? Race conditions are generally easier to exploit locally than remotely due to more predictable execution conditions. Certainly this is an under-tested vulnerability class though.

One presentation I wasn’t able to attend but want to follow up on is Nate McFeters, John Heasman, and Rob Carter’s talk which discussed the GIFAR attack I’ve been hearing so much about lately. The gist is that you can create a file that is both a valid GIF and a valid JAR, then use some Java applet tricks to initiate HTTP requests on behalf of the victim.

Finally, the Pwnie Awards didn’t fail to disappoint. Drama ensued over the Most Overhyped award, but at least this year some of the winners showed up to claim their awards! Halvar rapping Symantec lyrics was also quite memorable.

All in all, a fun and informative week, but as usual, I was relieved to get the hell out of Vegas and head home on Friday morning.

P.S. For a much more entertaining BlackHat/Defcon Recap, read Jennifer Jabbusch’s account of the week’s events. It’s my favorite one so far!

From Secunia:

Description:
Some vulnerabilities and a security issue have been reported in Apple Safari, which can be exploited by malicious people to disclose sensitive information or to compromise a user’s system.

1) A boundary error within the handling of BMP and GIF images can be exploited to trigger an out-of-bounds read and disclose content in memory.

2) A security issue exists due to Safari automatically launching downloaded executable files from sites in a Internet Explorer 7 zone with the “Launching applications and unsafe files” option set to “Enable”, or sites in the Internet Explorer 6 “Local intranet” or “Trusted sites” zone.

3) An unspecified error in the handling of Javascript arrays can be exploited to cause a memory corruption when a user visits a specially crafted web page.

Successful exploitation of this vulnerability may allow execution of arbitrary code.

The vulnerabilities are reported in Safari for Windows prior to version 3.1.2.

If you’re running it patch ‘er up. Or conversely you could just bite the bullet and get a Mac. (right, and use Firefox with NoScript. thx folks)

Article Link

Below is a screenshot of some of the user-generated comics that can be viewed. I’ve magnified the last pane of one of the strips using Flash’s “Zoom In” feature. Notice anything interesting?

Yep, it’s our old friend URL encoding, commonly used by web browsers to include non-alphanumeric characters into an HTTP request. Just interpret the %XX as a hex number, so %20 is the space character (decimal 32), %21 is an exclamation point (decimal 33) and so on. But why is it showing up in a Dilbert mashups?

My first thought was that someone must be poking around the Dilbert site looking for security holes. But then I noticed that it wasn’t just the one strip; a lot of them had the same problem. And it seemed unlikely that there were that many security-minded people messing with the site relative to the rest of the cubicle dwellers trying to come up with funny things for Dilbert to say.

My next thought was just that some developer just forgot to call urlDecode() — or whatever the Flash equivalent is — on the user-supplied punch line. Except that’s an oversimplication because: 1) it doesn’t happen on every strip, 2) the web server usually strips off the first layer of URL encoding so the backend wouldn’t see it unless it was double encoded (e.g. %2520), and 3) if you click on one of the thumbnail comics with the URL encoding anomaly, the full-size rendered version of the comic looks fine:

So clearly the “preview” code and the “full-size render” code are doing slightly different things with the same data, which may or may not have been properly decoded prior to being inserted into the database.

Any thoughts, readers? The pen tester in me wants to get to the bottom of this, but unlike some of the web app security people out there, I tend to be more conservative about hacking stuff without a signed contract. Also, I don’t think I can stand to read any more un-funny punch lines. But my gut tells me there is something fairly interesting going on behind the scenes here.

Oh finally, here’s a tip from Scott Adams himself on avoiding the Flash navigation and viewing the daily comic as a plain ol’ GIF.

What are the telltale signs that your company is already Computing in the Cloud?

Is it when the CIO makes a big announcement at the monthly IT meeting?

Is it when the IT newsletter drops a reference to pilot testing of some ‘web based’ software?

Or, is it when the secretary whips out the boss’s Corporate Credit Card and signs up to a Cloud Service?

Here are 12 indicators that your company is *already* part of the Cloud:

1. Your internal helpdesk reports fewer password resets.
2. Finance contacts you to confirm all the DVD readers are disabled - they are puzzled by the number of recurring credit card charges for Amazon (are the secretaries spreading out their orders for “Lost” DVDs again?).
3. You are asked to authorise a network change ticket to send all outbound network traffic via the perimeter firewall, before being routed back to the internal server room (for performance reasons). 
4. You walk into the Data Center and it feels cooler than usual.
5. When the builders next door accidentally saw through the company Internet connection, people complain there must be a DoS attack going on as they can’t get to their files.
6. During physical inspections, you notice unexplained gaps in server cabinets.
7. Login failures go down, in fact login “attempts” in general go down but the company car park is full.
8. As you walk through the office, you notice all the “Security Awareness” posters have been replaced with pictures of Jeff Bezos (!)
9. You are asked to authorise a visit from the local environment group.  Fearing protesters, you are surprised to learn that your company has won a prize for reducing its Carbon Footprint
10. Your Intrusion Prevention System is preventing the call center from uploading contracts stored as GIF files.
11. You detect the presence of ‘malware’ in the form of unexplained ‘Machine Images’ on IT’s desktops.
12. You stop finding Windows passwords under keyboards, instead you find random hex digits next to the words ‘Access Key’ and ‘Secret Key’.  You sigh, but at least they are setting difficult to guess passwords now!

If you are charged with IT security in your company, you may want to start checking your web proxy logs for telltale signs that people are talking to the Cloud…or just talk to finance.