tssci security

What web application security really is

I wanted to do a post about "what web application security really is" because plenty of people out there don't get it. They understand that "security attacks are moving from hosts to the Web", but they have no idea what that means. To most people, web application security is the same thing as website security. I see people trying to approach web application security in the same way that they have tried host security in the past: penetrate (web application security scanner) and patch (web application firewall) -- which won't work.

Web application vulnerabilities are different from regular vulnerabilities in more ways than you would think

Web application vulnerabilities are not a one-time thing. In a similar way, buffer overflows are also not a one-time thing, however we've been lying to ourselves for 20 years about it. The nice thing about buffer overflows is that they have been historically found with random input testing (e.g. fuzz testing) or code review as "one-off scenarios". A security researcher will find one, but that doesn't mean it's exploitable -- better yet it doesn't mean that the entire codebase is riddled with them (however, some repeat offenders obviously suffer from this problem).

With web application vulnerabilities, the more complex the app -- the more likely an adversary can make his or her dreams into an exploit reality

In the case of web application vulnerabilities -- one vulnerability means that there are often thousands of others -- hence the claimed high rate of false positives in automated security review tools -- with specific regard to SQL injection and XSS. What's even more clever about web application vulnerabilities is that they often work together -- they string together to form a bigger attack. A few little bugs equals one giant nasty bug. This also isn't the situation with fat applications -- a stack-based buffer overflow is usually one mean bug, but once it is patched properly the nightmare is [usually] over.

Web application profiling and Google Hacking read the developer's minds like Jedi magic tricks

Another problem with web application vulnerabilities is Google. Yes, Google. Before Google's code search, it was difficult to use Google to find a new buffer overflow. But such is not the case with web application vulnerabilities. All the blame isn't on just Google's search engine, but also MSN Live Search, Yahoo, and many others. It's so easy to just find a login form and start playing with specific, exploratory characters. Buffer overflows require buffers of a certain length with enough room for shellcode to overwrite EIP (or execute via cute pointer tricks) in order to establish a reliable exploit. Web application vulnerabilities don't worry about such restrictions. Once a web application is profiled (which could be as simple as an inurl:login.asp Google search), an intelligent adversary should already know numerous amounts of input techniques which will work against that specific type of application.

Web application vulnerabilities are like Legos for crimeware

Finally, adversaries aren't moving away from client-side vulnerabilities. They're just implementing the attacks differently. Web application vulnerabilities work well along with older host-based vulnerabilities. This isn't only because web application vulnerabilities can get inside the firewall. They open up many different doors for attack. Using Inter-protocol exploitation, it is possible to send shellcode through an XSS/CSRF/XHR worm. But it's also possible to send XSS worms through XSS worms or SQLi worms through XSS worms. Or XSS worms through SQLi worms. An adversary can put these types of attacks together however he or she wants.

Web app security today -- The 2008 SQL Injection Attacks (January - present)

The 2008 SQL Injection Attacks have spawned a lot of talk and controversy about web application vulnerabilties. It appears that if web application vulnerabilities were not mainstream in crimeware -- they now are.

The Microsoft Security Vulnerability Research and Defense blog had an excellent post regarding these SQL Injection Attacks. I think it dispells a lot of the myths about this attack, and it provide a lot of information on what to do about it. Of course, if you're not used to the developer terminology (as an IT security professional or manager), it's probably now as good as time as ever to read up, hire some experts, and get the word out.

There's a lot of links, but the most important one is how to identify and fix the problem. What's interesting is that a lot of the links talk about ASP.NET, but the attacks from Asprox's fake "Microsoft Security Center Extension" SQL injection attack tool only seem to currently target Classic ASP.

If you have access to IIS logs, you can also run the SQLInjectionFinder.exe tool. Of course, if you run a web application security scanner, you may or may not find SQL injections in your Classic ASP web application -- but this doesn't necessarily mean that you are or aren't hosting the Javascript malware. If you have a web application firewall, this doesn't mean that your web application can't be attacked via internal networks (assuming your web servers are listening on different interfaces) -- and it certainly doesn't mean that you aren't hosting the Javascript malware.

A better tool to test if you are hosting the Javascript malware would be to use a tool such as SpyBye.org. You can just set up your web browser to proxy through Spybye.org, or you can run it locally (e.g. to check your Intranet web applications) -- and it can also integrate with ClamAV. TS/SCI Security (well, Marcin and I) discussed this strategy when we did the Network Security Podcast with Rich Mogull and Martin McKeay.

Many faces of the same SQL injection attack

Also mentioned in the Microsoft Security Vulnerability Research and Defense blog post on the SQL Injection Attack is that it's not just one attack tool -- it's a bunch of tools and tactics. For those of you not familiar with Joe Stewart's SecureWorks article on Danmec/Asprox, be sure to give it a full read. Additionally, check out the SANS article from Bojan Zdrnja on the 10,000 web site infection mystery solved. My favorite is a quote from eWeek's article on Botnet Installs SQL Injection Tool:

Researchers are still investigating exactly what vulnerability on the Web sites is being exploited, Stewart said. The Web sites are English-language and their owners include law firms and midsize businesses. A similar attack technique is currently being seen spreading game-password-stealing Trojans from China. Whether the tool is related or only the attack syntax is shared, it is clear that SQL injection attack activity is on the rise from multiple sources, Stewart wrote in his blog.

Why WAF's are the wrong answer if you didn't get it the first or second time

When I see WAF support from organizations like SANS supporting Jeremiah Grossman -- as well as big companies like Imperva -- I immediately question their reliabilty as sources for expertise. If the web applications serving malware are largely owned by law firms and midsize businesses, then these are likely outside of the scope of SOX, PCI-DSS, GLBA, HIPAA, and BITS Shared Assessments. Many of these organizations don't even have the money or administrative staff to support WAF's as an option.

What works in web application security: Take 2

What these companies need is an IT decision to remove, replace, or recode any web applications which clearly demonstrate an affinity for SQL injection vulnerabilities (especially ones written in Classic ASP). If replacement or recoding are used, then it would be a good idea to establish some software risk guidelines such as how web application software is acquired and tested before loaded by a web server. It's not a matter of production or not -- all applications, internal/Intranet/lab/test/etc -- all of these applications need to be asset tagged and approved as tested. It's now considered important enough to know what web applications your organization is running because of the risk involved by a SQL injection (or other web application vulnerability) "drive-by".

Why we need action now

If we just let this malware sit dormant in web applications, we're in for a lot of trouble. All that is required for adversaries is to flip a switch -- and now they can deliver any new zero-day threat they desire. These could be websites you visit everyday. This could be web application code executed by your browser when you start it. It could even be your Intranet server, or a partner site you use. It could be your favorite online shopping site.

Don't hesitate to make a decision. The next wave of these attacks may not work through an antiquated botnet or a standalone tool. They will probably target PHP MySQL applications, ASP.NET applications, both, or even more. There may not be simple tools such as SQLInjectionFinder.exe or SpyBye to help locate these vulnerabilities -- and some could even stand the scrutiny of incident research for some time. How long did it take us to understand these SQL Injection attacks? Longer than 6 or 7 months?

If you think that implementing a WAF will save you (even in the short-term), please let us know why you believe this is the case. TS/SCI Security sees the WAF answer as FUD, lies, and/or short-sightedness. The best answer is to recode or replace while we still have the chance.

Posted by dre on Sunday, June 15, 2008 in Defense, Hacking and Security.

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