Let us create a 3D eBook for you!
Let us create a 3d Digital eBook for you! DigyCat.com

How Spammers Fool Bayesian Filters - And How to Stop Them


Effectively stopping spam over the long-term requires much more than blocking individual IP addresses and creating rules based on keywords that spammers typically use. The increasing sophistication of spam tools coupled with the increasing number of spammers in the wild has created a hyper-evolution in the variety and volume of spam. The old ways of blocking the bad guys just don't work anymore.

Examining spam and spam-blocking technology can illuminate how this evolution is taking place and what can be done to combat spam and reclaim e-mail as the efficient, effective communication tool it was intended to be.

One method used to combat spam is Bayesian Filtering. Named after Thomas Bayes, an English mathematician, Bayesian Logic is used in decision making and inferential statistics. Bayesian Filers maintain a database of known spam and ham, or legitimate email. Once the database is large enough, the system ranks the words according to the probability they will appear in a spam message.

Words more likely to appear in spam are given a high score (between 51 and 100), and words likely to appear in legitimate email are given a low score (between 1 and 50). For example, the words "free" and "sex" generally have values between 95 and 98, whereas the words "emphasis" or "disadvantage" may have a score between 1 and 4. Commonly used words such as "the" and "that", and words new to the Bayesian filters are given a neutral score between 40 and 50 and would not be used in the system's algorithm.

When the system receives an email, it breaks the message down into tokens, or words with values assigned to them. The system utilizes the tokens with scores on the high and low end of the range and develops a score for the email as a whole. If the email has more spam tokens than ham tokens, the email will have a high spam score. The email administrator determines a threshold score the system uses to allow email to pass through to users.

Bayesian filters are effective at filtering spam and minimizing false positives. Because they adapt and learn based on user feedback, Bayesian Filers produce better results as they are used within an organization over time. They are not, however, foolproof. Spammers have learned which words Bayesian Filters consider spammy and have developed ways to insert non-spammy words into emails to lower the message's overall spam score. By adding in paragraphs of text from novels or news stories, spammers can dilute the effects of high-ranking words. Text insertion has also caused normally legitimate words that are found in novels or news stories to have an inflated spam score. This may potentially render Bayesian filters less effective over time.

Another approach spammers use to fool Bayesian filters is to create less spammy emails. For example, a spammer may send an email containing only the phrase, "Here's the link?". This approach can neutralize the spam score and entice users to click on a link to a Web site containing the spammer's message. To block this type of spam, the filter would have to be designed to follow the link and scan the content of the Web site users are asked to visit. This type of filtering is not currently employed by Bayesian filters because it would be prohibitively expensive in terms of server resources and could potentially be used as a method of launching denial of service attacks against commercial servers.

As with all single-method spam filtering methodologies, Bayesian filters are effective against certain techniques spammers use to fool spam filters, but are not a magic bullet to solving the spam problem. Bayesian filters are most effective when combined with other methods of spam detection.

The Solution

When used individually, each anti-spam technique has been systematically overcome by spammers. Grandiose plans to rid the world of spam, such as charging a penny for each e-mail received or forcing servers to solve mathematical problems before delivering e-mail, have been proposed with few results. These schemes are not realistic and would require a large percentage of the population to adopt the same anti-spam method in order to be effective. You can learn more about the fight against spam by visiting our website at www.ciphertrust.com and downloading our whitepapers.

Dr. Paul Judge is a noted scholar and entrepreneur. He is Chief Technology Officer at CipherTrust, the industry's largest provider of enterprise email security. The company's flagship product, IronMail provides a best of breed enterprise anti spam solution designed to stop spam, phishing attacks and other email-based threats. Learn more by visiting http://www.ciphertrust.com/products/spam_and_fraud_protection today.


MORE RESOURCES:

Spam Blocker - Google News

This RSS feed URL is deprecated

This RSS feed URL is deprecated, please update. New URLs can be found in the footers at https://news.google.com/news

How To Block Robocalls: Automated Calls Are Rising, Here's How ... - International Business Times


International Business Times

How To Block Robocalls: Automated Calls Are Rising, Here's How ...
International Business Times
The Federal Trade Commission reported complaints about robocalls reached a new high in 2017. Here's how to block the unwanted calls from ringing your phone.

and more »

Cryptojacking Has Gotten Out of Control | WIRED - WIRED


WIRED

Cryptojacking Has Gotten Out of Control | WIRED
WIRED
Cryptojacking, which exploded in popularity this fall, has an ostensibly worthy goal: Use an untapped resource to create an alternative revenue stream for games or media sites, and reduce reliance on ads. It works by embedding a JavaScript component in ...

and more »

Digital publishers cry foul as Google exerts more control over an industry it already dominates - Times of India


Times of India

Digital publishers cry foul as Google exerts more control over an industry it already dominates
Times of India
Here's how the new Chrome browser ad blocking set-up will work: Chrome will have an ad blocker turned on by default. This will block "disruptive" or "intrusive" ads on web pages. Industry body Coalition for Better Ads (CBA), which Google joined this ...
An update on Better Ads | Web | Google Developers Google Developers
Microsoft removes Google's Chrome installer from the Windows Store The Verge

all 97 news articles »

Stop spam calls with the best call- and text-blocker apps - Digital Trends


Digital Trends

Stop spam calls with the best call- and text-blocker apps
Digital Trends
Unwanted calls and texts are a serious problem. There were almost 30 billion robocalls in the U.S. last year according to YouMail research. Thankfully, the Federal Communications Commission is acting to try and protect consumers from unwanted ...

T-Mobile's spam call blocking is coming to MetroPCS - The Verge - The Verge


The Verge

T-Mobile's spam call blocking is coming to MetroPCS - The Verge
The Verge
Back in March, T-Mobile introduced Scam ID and Scam Block, two features that help users avoid annoying robocalls, and now it's bringing the service to MetroPCS. Starting tomorrow, all MetroPCS users will automatically get Scam ID, the feature that ...
MetroPCS Fights Spam Calls Through Scam ID, Scam Block Android Headlines
MetroPCS customers get Scam ID and Scam Block this week TmoNews
Scam ID and Scam Block coming to Metro PCS to stop scammers ... 9to5Mac
T-Mobile Newsroom
all 19 news articles »

Verizon is charging for anti-spam features T-Mobile and AT&T give away for free - The Verge


The Verge

Verizon is charging for anti-spam features T-Mobile and AT&T give away for free
The Verge
More important, however, is the fact that competing carriers offer robocall and spam warnings to their subscribers for free. T-Mobile, for instance, even does so on a network level, so you don't have to download an extraneous app. T-Mobile announced ...

and more »

How to Stop Spam Calls Before You Kill Your Phone - Gizmodo


Gizmodo

How to Stop Spam Calls Before You Kill Your Phone
Gizmodo
Nomorobo, which is used by some carriers, just launched on iOS and identifies spam calls in a similar way—it will set you back $1.99 a month, but unlike Hiya, it won't touch your contacts or call history. Meanwhile, Should I Answer? is free for ...

BT's spam blocker IDs accident claims as top nuisance call • The ... - The Register


The Register

BT's spam blocker IDs accident claims as top nuisance call • The ...
The Register
BT's free spam filter, launched earlier this year to crack down on nuisance calls, has identified accident claims as the worst offender for nuisance calls with 12 million made in the first week of March. Some two million customers have signed up to the ...

and more »

How to block spam on your phone | Fox News - Fox News


Fox News

How to block spam on your phone | Fox News
Fox News
Ting! You've received a new message. You put down your shopping bags, dig into your pocket and pull out your smartphone — and then you frown, because it's from a phone number you've never seen in your life, and the message reads: “REAL ROLEX 90% OFF!”

and more »

LargeFriends.com - the best dating site for plus-sized singles!
SuccessfulMatchCentral.com - the best dating site for plus-sized singles!

PreLaunchX

DigyCat Domain Is For Sale - $105,000 For Enquiries eMail Us

© www.DigyCat.com - 2012

home | site map | links