Spam By Dan Sterrett

Overview ► What is spam? ► Why it’s a problem ► The source of spam ► How spammers get your address ► Preventing Spam ► Possible solutions

What is Spam? ► Unsolicited commercial ► Sent in bulk ► Advertisements (weight loss, prescription drugs, etc)

Problem with spam ► Annoying ► Time consuming  You could have a hundred spam messages for each legitimate message ► Spam filters aren’t perfect ► More internet traffic ► Cheap for the spammer

Example Subject: Adobe Suppose we tell you that you could really lose up to 82% of your unwanted body fat and keep it off in just a few months, would you be interested? We certainly hope so! Please visit our web site - Click here!

Spam Stats ► In a single day in May 2003:  AOL blocked 2 billion spam messages  MSN blocked 2.4 billion spam messages

Where do they get my address? ► Spambots  Search engines that spider the web looking for the sign. ► Newsgroups and chat rooms  Especially in big companies like AOL, people often use their screen names in chat rooms  In newsgroups people leave their actual addresses  Spammers have pieces of software that automatically extract these screen names and addresses

Where do they get my address? ► Websites created specifically to attract addresses Win $1 million!!! Just type your address here!"

Where do they get my address? ► Websites sell your address  Created "opt-in" lists by asking, "Would you like to receive newsletters from our partners?"

Where do they get my address? ► "dictionary" search of the servers of large hosting companies like MSN, AOL or Hotmail  Software opens a connection with the server and sends millions of random addresses and records which ones are “live” ► Spammers sell your address to other spammers

Where do they get my address? ► Spammers buy addresses  Google add

Preventing Spam ► Spam filtering software  Simplest filters use keywords in the subject line to identify spam  Looks for words such as sex, viagra, etc.  Spammers change the spelling ► s-e-x ► Via9ra  Hard for filtering software to keep up  Sometimes blocks legitimate

Spam Filters ► Heuristic filters  Scan message statistically looking at word patterns and word frequency.  Spammers use shorter messages

Prevention ► Large ISPs tried blocking multiple s with the same subject line or message body ► Unwanted side-effect  blocked newsletters  ISPs made "white lists" to identify legitimate newsletter senders.  Then spammers sidestepped the issue by inserting different random characters into each subject line and message body.

Prevention ► You could get an with a subject line  Women Wanted puklq  The letters “puklq” are random and are attached at the end of the subject line for each sent out. ► Organizations that list IP addresses used by spammers (Spamhaus.org is an example) ► Companies that host accounts can check the source IP address

Prevention ► Spammers can get around this by changing IP addresses often  The next person to receive one of these IP addresses won’t be able to send . ► Zombie machines  Viruses can be sent out to recruit “zombie machines”  Usually personal computers of unsuspecting people. Spammers route spam through these machines.  Have been used for DoS attacks on places like Spamhaus.org

Prevention ► Hide addresses on websites  Use javascript, etc.  Simple spambots won’t recognize it

Possible Solutions ► “Do Not Spam List”  Not a good idea ► Online forms  Use instead of  Drawbacks ► Need your own website ► Time consuming to send a message

Sources ► tm ► html html html ► 63.php