Browser Security

The Future Of Application And Database Security: Part 2, Browser To WAF/Gateway

By Rich

Since Friday is usually "trash" day (when you dump articles you don't expect anyone to read) I don't usually post anything major. But thanks to some unexpected work that hit yesterday, I wasn't able to get part 2 of this series out when I wanted to. If you can tear yourself away from those LOLCatz long enough, we're going to talk about web browsers, WAFs, and web application gateways. These are the first two components of Application and Database Monitoring and Protection (ADMP), which I define as:

Products that monitor all activity in a business application and database, identify and audit users and content, and, based on central policies, protect data based on content, context, and/or activity.

Browser Troubles

As we discussed in part 1, one of the biggest problems in web application security is that the very model of the web browsers and the World Wide Web is not conducive to current security needs. Browsers are the ultimate mashup tool- designed to take different bits from different places and seamlessly render them into a coherent whole. The first time I started serious web application programming (around 1995/96) this blew my mind. I was able to embed disparate systems in ways never before possible. And not only can we embed content within a browser, we can embed browsers within other content/applications. The main reason, as a developer, I converted from Netscape to IE was that Microsoft allowed IE to be embedded in other programs, which allowed us to drop it into our thick VR application. Netscape was stand alone only; seriously limiting its deployment potential.

This also makes life a royal pain on the security front where we often need some level of isolation. Sure, we have the same-origin policy, but browsers and web programming have bloated well beyond what little security that provides. Same-origin isn't worthless, and is still an important tool, but there are just too many ways around it. Especially now that we all use tabbed browsers with a dozen windows open all the time. Browsers are also stateless by nature, no matter what AJAX trickery we use. XSS and CSRF, never mind some more sophisticated attacks, take full advantage of the weak browser/server trust models that result from these fundamental design issues.

In short, we can't trust the browser, the browser can't trust the server, and individual windows/tabs/sessions in the browser can't trust each other. Fun stuff!

WAF Troubles

I've talked about WAFs before, and their very model is also fundamentally flawed. At least how we use WAFs today. The goal of a WAF is, like a firewall, to drop known bad traffic or only allow known good traffic. We're trying to shield our web applications from known vulnerabilities, just like we use a regular firewall to block ports, protocols, sources, and destinations. Actually, a WAF is closer to IPS than it is to a stateful packet inspection firewall.

But web apps are complex beasts; every single one a custom application, with custom vulnerabilities. There's no way a WAF can know all the ins and outs of the application behind it, even after it's well tuned. WAFs also only protect against certain categories of attacks- mostly some XSS and SQL injection. They don't handle logic flaws, CSRF, or even all XSS. I was talking with a reference yesterday of one of the major WAFs, and he had no trouble slicing through it during their eval phase using some standard techniques.

To combat this, we're seeing some new approaches. F5 and WhiteHat have partnered to feed the WAF specific vulnerability information from the application vulnerability assessment. Imperva just announced a similar approach, with a bunch of different partners.

These advances are great to see, but I think WAFs will also need to evolve in some different ways. I just don't think the model of managing all this from the outside will work effectively enough.

Enter ADMP

The idea of ADMP is that we build a stack of interconnected security controls from the browser to the database. At all levels we both monitor activity and include enforcement controls. The goal is to start with browser session virtualization connected to a web application gateway/WAF. Then traffic hits the web server and web application server, both with internal instrumentation and anti-exploitation. Finally, transactions drop to the database, where they are again monitored and protected.

All of the components for this model exist today, so it's not science fiction. We have browser session virtualization, WAFs, SSL-VPNs (that will make sense in a minute), application security services and application activity monitoring, and database activity monitoring. In addition to the pure defensive elements, we'll also tie in to the applications at the design and code level through security services for adaptive authentication, transaction authentication, and other shared services (happy Dre? :) ). The key is that this will all be managed through a central console via consistent policies.

In my mind, this is the only thing that makes sense. We need to understand the applications and the databases that back them. We have to do something at the browser level since even proper parameterization and server side validation can't meet all our needs. We have to start looking at transactions, business context, and content, rather than just packets and individual requests.

Point solutions at any particular layer have limited effectiveness. But if we stop looking at our web applications as pieces, and rather design security that addresses them as a whole, we'll be in much better shape. Not that anything is perfect, but we're looking at risk reduction, not risk elimination. A web application isn't just a web server, just some J2EE code, or just a DB- it's a collection of many elements working together to perform business transactions, and that's how we need to look at them for effective security.

The Browser and Web Application Gateway

A little while back I wrote about the concept of browser session virtualization. To plagiarize myself and save a little writing time so I can get my behind to happy hour:

What we ideally need is a way to completely isolate our content in the browser. One way to do this is session virtualization, pioneered by GreenBorder, who was later acquired by Google (the GreenBorder site is just in support mode now). When a user connects to our site, we push down some code to create a virtual environment in the browser that we strictly control. We wall off that session, which could just be an isolated iFrame in a page, so that it only accesses content we send it. Basically, we break the normal browser model and hijack what we need. This would, for example, help stop CSRF since other browser elements won't be able to trigger a connection to our application. Done right, it limits man in the middle attacks, even if the user authorizes a bad digital certificate. To work properly, this needs to be tied to a gateway that controls the session. While we could do it from the web/app server itself, I suspect we'll see this as a web application firewall feature, just as we see similar features from SSL-VPNs. I think isolated WAFs have a very limited lifespan, but this is exactly the kind of feature that will extend their value. Better yet, we can tie this in to our Application and Database Monitoring and Protection to build a browser-to-database protected path. We can completely track a transaction or piece of content from the database server to the browser and back. We could even use this to isolate out potentially "bad" content in an in-browser sandbox. For example, it could be a way to enable all those social networking widgets in a more controlled way but locking in potentially bad content instead of known good. Will this protect us from keystroke sniffers or a completely compromised host? Nope, but it will definitely help with a large number of our current browser security issues. If we combine it with full ADMP and additional methods like transaction authentication, I think we can regain a bit of control of the web application security mess.

Thus we see one migration path for a WAF. A user goes to connect to the application and hits the WAF, which is now more of a Web Application Gateway. The gateway, like an SSL-VPN, sends the session virtualization code down to the browser. We do this outside of the web application for performance reasons. The secure virtual session is established and the gateway then allows communications with the application behind it.

For things like retail and financial sites that include only limited third party content if any, we can monitor activity from the browser through to the application and work within the isolated session. It both improves our ability to control what's being sent to the browser, and gives us a higher degree of confidence that what's coming from the browser is safe. We still validate everything, but since we're tied to the application itself we can validate in the browser and at the gateway before we even hit the app (and further validate there). Since in a controlled environment we know what transactions should be allowed (or not), we have more ability to detect and block "bad" transactions like SQL injection from the user.

In less controlled environments- thing MySpace or Gmail and everything in between- the gateway also becomes a filter for third party content. Like Checkpoint's new ForceField. The gateway filters out, to the best of its ability, harmful third party content coming from third party sites. Basically, it becomes an SSL-VPN for secure browsing.

This is obviously not viable for all sites due to bandwidth considerations, and in those circumstances we'll drop this part and stick to the rest of the ADMP stack, or only virtualize our pieces of content knowing the user is at risk for the third party stuff we're still linking them to.

Future of the WAF, Option 2

I've just described a scenario where the WAF extends into a Secure Web Application Gateway that adds virtualization, encryption, and content filtering. That doesn't mean WAFs won't also still exist in non-virtualized situations, since that will still be a massive volume of sites out there.

For these sites the WAF continues to progress with deeper application integration and application understanding, and works with the elements I'll describe later that will be embedded into the applications and databases. Rather than hanging around outside the application with barely any idea what's going on behind it, the WAF will take its cues from the app, help manage sessions, and monitor activity outside the app to block the few things we know we can pick up at that layer.

Why use the WAF at all? To give us a choke point and offload some of the monitoring and processing that could hurt application performance. Let's be honest- maybe WAFs will eventually go away, but performance problems alone will probably keep next-gen WAFs viable for a while. There are also plenty of things we can now block before they ever hit the application controls, which, by nature of being integrated at the app level, will be more complex and delicate.

But again, by tightly integrating with our other layers, instead of naievely assuming that an external black box will magically solve our problems, we get a much higher level of functionality. Feeding in vulnerability data as we're just starting to do is a good beginning, but once we plug in deeper to the application and database servers we'll get entirely new levels of functionality.

Part 2 Conclusions

What I've described today is how we can build a (more) trusted path from the browser to the face of the application. WAFs will add gateway capabilities, both protecting the applications behind them and the browsers in front of them. Since this won't be the right approach in all circumstances, WAFs will also evolve with tighter integration to the application and other ADMP stack components.

Again, this might sound like little more than the usual analyst fiction, but all the components are here today. Also, I don't expect my predictions to be totally accurate. I'm roughly guessing I'm at 85% or so.

Next week I'll start digging into the application and database. We'll talk about application instrumentation, anti-exploitation, DAM, trusted transaction paths, and shared security services.

–Rich

The Future Of Application And Database Security: Part 1, Setting The Stage

By Rich

I've been spending the past few weeks wandering around the country for various shows, speaking to some of the best and brightest in the world of application and database security. Heck, I even hired one of them. During some of my presentations I laid out my vision for where I believe application (especially web application) and database security are headed. I've hinted at it here on the blog, discussing the concepts of ADMP, the information-centric security lifecycle, and DAM, but it's long past time I detailed the big picture.

I'm not going to mess around and write these posts so they are accessible to the non-geeks out there. If you don't know what secure SDLC, DAM, SSL-VPN, WAF, and connection pooling mean, this isn't the series for you. That's not an insult, it's just that this would drag out to 20+ pages if I didn't assume a technical audience.

Will all of this play out exactly as I describe? No way in hell. If everything I predict is 100% correct I'm just predicting common knowledge. I'm shooting for a base level of 80% accuracy, with hopes I'm closer to 90%. But rather than issuing some proclamation from the mount, I'll detail why I think things are going where they are. You can make your own decisions as to my assumptions and the accuracy of the predictions that stem from them.

Also, apologies to Dre's friends and family. I know this will make his head explode, but that's a cost I'm willing to pay. Special thanks to Chris Hoff and the work we've been doing on disruptive innovation, since that model drives most of what I'm about to describe. Finally, this is just my personal opinion as to where things will go. Adrian is also doing some research on the concept of ADMP, and may not agree with everything I say. Yes, we're both Securosis, but when you're predicting uncertain futures no one can speak with absolute authority. (And, as Hoff says, no one can tell you you're wrong today).

Forces and Assumptions

Based on the work I've been doing with Hoff, I've started to model future predictions by analyzing current trends and disruptive innovations. Those innovations that force change, rather than ones that merely nudge us to steer slightly around some new curves. In the security world, these forces (disruptions) come from three angles- business innovation, threat innovation, and efficiency innovation. The businesses we support are innovating for competitive advantage, as are the bad guys. For both of them, it's all about increasing the top line. The last category is more internal- efficiency innovation to increase the bottom line. Here's how I see the forces we're dealing with today, in no particular order:

1. Web browsers are inherently insecure. The very model of the world wide web is to pull different bits from different places, and render them all in a single view through the browser. Images from over here, text from over here, and, using iframes, entire sites from yet someplace else. It's a powerful tool, and I'm not criticizing this model; it just is what it is. From a security standpoint, this makes our life more than a little difficult. Even with a strictly enforced same origin policy, it's impossible to completely prevent cross-site issues, especially when people keep multiple sessions to multiple sites open all at the same time. That's why we have XSS, CSRF, and related attacks. We are trying to build a trust model where one end can never be fully trusted.
2. We have a massive repository of insecure code that grows daily. I'm not placing the blame on bad programmers; many of the current vulnerabilities weren't well understood when much of this code was written. Even today, some of these issues are complex and not always easy to remediate. We are also discovering new vulnerability classes on a regular basis, requiring review and remediation on any existing code. We're talking millions of applications, never mind many millions of lines of code. Even the coding frameworks and tools themselves have vulnerabilities, as we just saw with the latest Ruby issues.
3. The volume of sensitive data that's accessible online grows daily. The Internet and web applications are powerful business tools. It only makes sense that we connect more of our business operations online, and thus more of our sensitive data and business operations are Internet accessible.
4. The bad guys know technology. Just as it took time for us to learn and adopt new technologies, the bad guys had to get up to speed. That window is closed, and we have knowledgeable attackers.
5. The bad guys have an economic infrastructure. Not only can they steal things, but they have a market to convert the bits to bucks. Pure economics give them viable business models that depend on generating losses for us.
6. Bad guys attack us to steal or assets (information) or hijack them to use against others (e.g., to launch a big XSS attack). They also sometimes attack us just to destroy our assets, but not often (less economic incentive, even for DoS blackmail).
7. Current security tools are not oriented to the right attack vectors. Even WAFs offer limited effectiveness since they are more tied to our network security models than our data/information-centric models.
8. We do not have the resources to clean up all existing code, and we can't guarantee future code, even using a secure SDLC, won't be vulnerable. This is probably my most contentious assumption, but most of the clients I work with just don't have the resources to completely clean what they do have, and even the best programmers will still make mistakes that slip through to production.
9. Code scanning tools and vulnerability analysis tools can't catch everything, and can't eliminate all false positives. They'll never catch logic flaws, and even if we had a perfect tool, the second a new vulnerability appeared we'd have to go back and fix everything we'd built up to that point.
10. We're relying on more and more code and web services developed by others. From machine-generated web applications, to frameworks and off-the-shelf web apps we customize, to mashups where we directly pass content generated by someone else to our users.
11. "Web applications" is a misnomer- we mean the entire stack: web servers, web application servers, the databases behind them, and all the various interconnected n tiers. Many of these are internally accessible, creating an additional vector for attack.

To rephrase these a bit:

1. Bad guys are focused on our web applications, and are intelligent and motivated.
2. We have a lot of insecure code, keep generating more, and can't rely on secure development to fix it all.
3. WAFs and code scanning help, but aren't enough.
4. We need to protect a big, complex stack including content and services outside our control.

Following these forces, I'm drawing some assumptions about what any solution needs to look like:

1. We need to include browser elements, but can't trust the browser.
2. We need to monitor and enforce at the transaction level, both for audibility and for logic flaws and other security issues.
3. Such monitoring and enforcement needs to run from the browser to the database.
4. Any solution needs to understand the application and database, not just layer over it.
5. We need to filter anything we pass on to the user.
6. We need to focus on protecting the information.

I'm not totally thrilled with how I've laid this out, but I think it's reasonably understandable. Tomorrow I'll walk through how I think the technology will develop, and where today's tools fit in. I suspect Adrian will start chiming in, once he gets off the road, with his own interpretations.

–Rich

There Are No Safe Web Sites

By Rich

I spend a reasonable amount of time writing security articles for the consumer audience over at TidBITS, never mind this site. When I talk about browser security, one of my top tips is to avoid risky behavior and "those" sites. Although that's pretty standard advice, it's become a load of bollocks, and I can no longer give it in good conscience.

I spend a lot of time these days focusing on web application security and talking with some of the leading web app researchers like Rnake and Jeremiah Grossman. It's increasingly obvious that a combination of cross site scripting and some more nefarious web app attacks are destroying the concept of "safe" websites. We've seen everything from banks, to security vendors, to advertising servers, to major providers like Google and Yahoo, fall victim to attacks where malicious content is embedded or executed in the context of the trusted sites. PayPal may make a big deal about extended validation digital certificates and colorful anti-phishing banners, yet an EV cert doesn't do squat if the bad guy sneaks in a little malicious JavaScript and you've now run the nasty code in a trusted context.

Today, Dark Reading ran an article on some major security sites with cross site scripting vulnerabilities. Combined with a few beers with Rsnake last week, it pushed me over the edge.

These days, it's hard to call any site trusted. Thats one reason I've shifted to my multi-browser/multi-operating system strategy. Realistically, I can't tell everyone in the world to adopt my level of paranoia. In part because as bad as things are, most people aren't suffering real damage because of it. That said, it strongly emphasizes the need not only to keep your system up to date, but to at least split browsers for financial vs. regular sites.

It also strongly points to the need to change the fundamental trust model of browsers, and to push us in the security industry towards solutions like ADMP and browser session virtualization (or better yet, a combination of both).

This isn't a "the world is ending" post. It's merely a recognition that "safe" browsing is only a partial security control these days, and one that's losing effectiveness. We need to think about adopting new strategies before we start seeing more mass exploitation leveraging commonly trusted sites. One that transcends current browser trust models, which do little but make life easier for the smart attackers who take advantage of them.

Oh yeah, and stop wasting money on EV certs.

–Rich

Making The Move To Multiple Browsers

By Rich

For a while now I've been using different web browsers to compartmentalize my risk. Most of my primary browsing is in one browser, but I use another for potentially risky activities I want to isolate more. Running different browsers for different sessions isolates certain types of attacks. For example, unless someone totally pwns you with malware, they can't execute a CSRF attack if you're on the malicious site in one browser, but using a totally separate browser to check your bank balance. Actually, to be totally safe you shouldn't even run both browsers at the same time.

Last night I was talking with Robert "Rsnake" Hansen of SecTheory about this and he finally convinced me to take my paranoia to the next level.

Here's the thing- what I'm about to describe may be overkill for many of you. Because of what I do for a living my risk is higher, so take this as an example of where you can take things, but many of you don't need to be as paranoid as I am. On the other hand, Robert is at even higher risk, and takes even more extreme precautions. I also purposely use a combination of virtualization and browser diversity to further limit my exposure. In all cases there are completely different applications, not just instances of the same platform.

My web browsers break out like this. I won't list which specific browsers I use except in a few cases:

1. Everyday browsing: low risk, low value sites. I use one of the main browsers, and even use it to manage my low value passwords.
2. Everyday browsing 2: slightly higher risk, but even lower value. Basically, it's the browser in my RSS reader.
3. Blog management: a third browser dedicated to running Securosis. This is the bit Robert convinced me to start. I use it for nothing else.
4. Banking: Internet Explorer running in a Windows XP virtual machine. I only use it for visiting financial sites. To be honest, this is as much a reflection of my bank's web app as anything else. I can deposit using my scanner at home, but only in IE on Windows.
5. High risk/research: a browser running in a non-persistent Linux virtual machine. Specifically, it's Firefox running off the Backtrack read-only ISO. Nothing is saved to disk, and that virtual machine doesn't even have a virtual hard drive attached.

This setup isn't really all that hard to manage since it's very task-based. Now the truth is this only protects me from some (major) web based attacks. If my system is compromised at the host OS level, the attacker can just capture everything I'm doing and totally own me. It doesn't prevent the browser from being that vector, so, like everyone, I take the usual precautions to limit the possibility of malware on my system (but no AV, at least not yet).

For average users I recommend the following if you don't want to go as far as I have:

1. One browser for everyday browsing. I like Firefox with NoScript.
2. Another for banking/financial stuff.
3. If you go to "those" sites, stick with a virtual machine. Oh, don't pretend you don't know what I'm talking about.

–Rich