Bugtraq mailing list archives
Re: Sanctum AppScan 4 misses potential vulnerabilities in wrapped links
From: Valdis.Kletnieks () vt edu
Date: Fri, 26 Sep 2003 11:49:53 -0400
On Fri, 26 Sep 2003 09:35:46 +0200, "Dawes, Rogan (ZA - Johannesburg)" <rdawes () deloitte co za> said:
I am inclined to agree with Sanctum's position here. Without actually executing the javascript, and triggering all the possible events, and would be overlooked by this technique. I'm still of the opinion that *no* automated tool can provide complete coverage of an arbitrary web application, simply because of the potential complexity. It's like solving the halting problem, to my mind.
That's because it *is* the Turing Halting Problem, more or less. Fortunately, we can mostly work around the problem by applying some constraints to the problem space - for instance, we can simulate the Javascript and see if what pops out is "legal" or "illegal". We then finesse the Turing issues by simply declaring that any Javascript that takes over X amount of resources (CPU, memory, network accesses, whatever) is tossed in the "illegal" pile. This is demonstrably free of both Turing issues (since every test is guaranteed to produce a result in X or less) and fulfills the Principle of Least Surprise ("I'd not have asked to visit that webpage if I knew it would take 2 hours to do so"). The biggest remaining issue is the totally b0rked Javascript security model - it isn't clear that it's possible to write an accurate simulator that does it correctly. The proof of this statement is the obvious fact that if it WERE possible to write such a beast, vendors would be shipping it as their Javascript interpreter. ;)
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Current thread:
- RE: Sanctum AppScan 4 misses potential vulnerabilities in wrapped links Dawes, Rogan (ZA - Johannesburg) (Sep 26)
- Re: Sanctum AppScan 4 misses potential vulnerabilities in wrapped links Valdis . Kletnieks (Sep 26)