Date: Thu, 12 Jun 2003 20:06:55 -0500 From: David Kelly <dkelly@HiWAAY.net> To: chat@FreeBSD.org Subject: Re: Antivirus for (mailservers on) FreeBSD Message-ID: <200306122006.55906.dkelly@HiWAAY.net> In-Reply-To: <3EE8DB83.4040609@potentialtech.com> References: <5.2.1.1.2.20030612202321.02e28008@194.184.65.4> <20030612193524.GA31199@grumpy.dyndns.org> <3EE8DB83.4040609@potentialtech.com>
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On Thursday 12 June 2003 02:58 pm, Bill Moran wrote: > David Kelly wrote: > > How does "antivirus mail filtering" differ significantly from spam > > filtering? Seems to me these two should be one and the same as > > "spam" is a form of malicious code. > > No, no, no. Not even close. > > While it may seem that way to an end-user, programatically it's very > different. > > Bayesan matching is generally done for spam, as it seems to be the > best approach. This involves checking for a LARGE number of > conditions and assigning a percentage likelihood for each that it is > indicative of spam. Once _every_ condition has been checked, the > email is labeled spam or not based on the sum of the liklihoods of > all matched rules. This is VERY cpu intensive. So what? If you are already pushing the message thru a spam filter then while you are at it and have the message in hand then run a malicious code check. If you are going to check for malicious code anyhow then it shouldn't ultimately take more CPU cycles to do it from the spam filter interface. No matter such malicious code is often hidden in .zip or .exe attachments. Simply look there too. I am not suggesting use of optimized-for-spam search techniques against malicious code, but optimized-for-code techniques from within the same framework. -- David Kelly N4HHE, dkelly@hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system.
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