Home Page

Firewalls

Email & Spam

Security Terminology

Security Topics

VPN & Cryptography

Wireless

 

Email Security and Spam Terminology

Zero Day Window

BATV

Bayesian Algorithm

Content and Connection control

Directory Harvesting Attacks

Email Encryption

Email Archiving

File attachments

Image scanning

Email Load balancing

Port forwarding and MX records

Reputation filters

Encrypted attachments

Grey Listing

Email Monitoring

Internal Email Security

Open Relay

Outbound email filtering

Per user quarantine area

Reverse DNS lookup & SPF

RFC Compliant emails

SMTP IMAP4 or POP3

Spoofed email

Stopping spam for Networks guide

Email Throttling

What is Spam

Which Spam filter

Whitelists and Blacklists

 

Security Products Guide

Which Anti-Virus Software?

Which Firewall?

Which Spam Filter?

Which Internet Security Suite?

 

What is Guide

What is a Firewall?

What is a Virus?

What is Spam?

 

Essential Security Guides

Securing Windows XP Guide

Securing Windows Vista Guide

A Guide to Wireless Security

 

Other

Top 8 Internet Security Tips

Why both, Firewall and Anti Virus?

Free or purchased security - Which one?

 

 

 

 

Image Scanning

 

Images can just as easily break laws, send out abusive immoral messages, offend staff and damage company reputation. Images coming from your company can make you liable to prosecution and attract unwanted media. Some firewall proxy servers support image scanning usually purchased as an additional subscription, which can detect pornography and other unsuitable material.

Image Manager from Clearswift's MIMEsweeper for SMTP not only scans for images within the body of an email, but also scans for images deep within attached files, completely breaking them down extracting embedded images and passing them on to Image Manager to scan for unwanted images.

When Image Manager is scanning for images, first it checks its pre-populated database. It checks the hash of the image and compares this hash with hashes within it's database. These hashes within the database are a bulk of known images downloaded from Clearswift servers periodically.

If there is no match within the database then image manager scans the image and looks for certain characteristics within the image to classify appropriately. These features and characteristics are compared to it's built in image feature database. This database contains values for thousands of features, and if the feature matches with one in the database or even a close match, then appropriate action is taken depending on the classification of the matched feature within the database. So if the feature that it is matched to within the database is known to be a violent image, then image manager will classify this scanned image as spam.

Further Reading

Wikipedia's guide to Spam Techniques