Posts Tagged ‘content-filters’

Post #7 on Why Spam Filters Suck “trickle blog” series

Posted: Wednesday, April 30, 2008
Posted by d.liao.

Slowing Things Down The problem is, typical email systems work in a queue. This means that high spam traffic clogs your network and crowds out legitimate mail. Botnets pour messages into your network, and mail servers receive the messages as quickly as they can. Next, the spam filter analyzes and tries to filter out any messages that appear to be spam. Filters are effective at separating spam from email but do nothing to stop the rising volume of SMTP connections hammering the server. When spam traffic rises, the server becomes overloaded and results in delivery delays for all email, similar to how a backlogged exit ramp can impede the flow of traffic on a highway during peak hours. Today, Internet facing email servers accept thousands of emails per minute. As spam volume increases, so too does the CPU required to process all that mail. The blunt solution is to scale […]

Post #3 on Why Spam Filters Suck “trickle blog” series

Posted: Monday, April 07, 2008
Posted by d.liao.

Once Promising Proposals for a Final Ultimate Solution to the Spam Problem (FUSSP) “Two years from now, spam will be solved.” That was Bill Gates’ famous pronouncement back in 2004. Microsoft, Yahoo and the open source community devised two techniques that they believed would eradicate spam. The first was sender authentication, which allowed email senders to provide a list of the servers permitted to send email for users within their domain. The idea was that sender authentication would eliminate spammers spoofing legitimate email addresses, and allow for the creation of a permanent, ironclad white list of trustworthy domains that never send spam, thus allowing recipients to simply block everything not on the white list and end spam forever. Another idea pitched in 2004 was the computational challenge. Senders would, upon connecting to a receiving email server, have to spend considerable CPU cycles computing the answer to a mathematical challenge provided […]

Taking the text out of the Spam

Posted: Thursday, November 22, 2007
Posted by pwhelan.

For spammers, the trouble with image and video spam is that they have to ultimately give you information. Selling Viagra – you need to know where to buy it. Stock pump and dump – you need to know what stock you need to buy. So, leaving audio based spam aside for now, the text has to be given to you and it has to be readable, or it’s of no use to the spammers. Text-based spam content-filtering has come a long way, so as long as we can extract the text from the images and video, we should be able to run that text through the existing text filters. Many top websites use “Captchas”. This is distorted text, designed to be unreadable by computers (used in automation by spammers), but is readable by humans. This is exactly what spammers are trying to do with image-spam. Whilst websites are using distorted […]