On 11-Sep-08, at 8:24 PM, Likarish, Peter F wrote:

> I'm a grad student doing anti-phishing research and lately I've been  
> comparing the performance of FF2 and FF3 with regard to site  
> detection.  FF2 has been substantially outperforming FF3 against our  
> test set of phishing attacks (generally garnered from published  
> online repositories of phishing attacks).  Based on my outsider's  
> perspective, I was under the impression that both relied on Google's  
> Safebrowsing and was surprised by the disparity between versions.  I  
> am wondering if this is a generally observed phenomenon or if we are  
> doing something odd in testing that could be causing it?  If anyone  
> has a chance to enlighten me, I would greatly appreciate it.


Hi Peter,

Can I ask what your methodology looks like?  We've had some  
conversations with another grad student doing similar research, and  
found that his set up involved running the tests immediately after the  
browser started up with a new profile, or in short bursts.  Because we  
use a local DB for the checks rather than pinging out to a network  
host to check every URL, Firefox needs to pull down a complete  
database of blocked sites before it will be effective.  Because we  
don't want to eat up all our users bandwidth, this is done in pulses,  
so it can take several hours to get a complete list.  Once the  
database has been built out, incremental updates are delivered about  
every 30 minutes which include any additions or deletions since the  
last update.  In typical usage scenarios, where a user will be using  
the browser regularly over the course of months or years, this build- 
out time is an acceptable lag, but in a test environment it could  
easily confuse your results.

Does this sound like it could be something that's tripping you up as  
well?  In the case of the other researcher, he was able to get much  
more accurate data by leaving Firefox idle for a day to build up a  
complete profile before starting his tests.

Cheers,

Johnathan

---
Johnathan Nightingale
Human Shield
[EMAIL PROTECTED]



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