The company said it is now blocking web beacons, which can be used to help spammers identify active email addresses, and said recently introduced authentication technology has reduced the amount of Hotmail accounts being used by spammers.
Web beacons, also known as web bugs, are invisible single-pixel GIF images that can be included in HTML documents so that each time the page is accessed, the access is logged on the web server where the image is stored.
Marketers use the technology to track surfing patterns. Used in conjunction with cookies, they can be used to single out unique users. Spammers use the beacons to verify that an email sent to an address generated randomly in a dictionary attack is in use.
Microsoft said that from now on all images embedded in HTML email will not be loaded when a user accesses the mail, unless the send is in their contact book or they specifically elect to open the image.
This should prevent web bugs from being used. This in itself will not stop spam arriving, but it will make dictionary-based spam attacks more difficult, as the spammer will have no way of knowing which email addresses are valid.
MSN says that it blocks 2.4 billion spams per day – a whopping 80% of its total incoming email, which is about double the accepted estimate for internet-wide spam volumes – evidence that dictionary attacks are a major problem.
MSN also said yesterday that a recently introduced Human Interactive Proof feature, which requires a person to pass a Turing-style test before they sign up for a new account, has seen the number of new accounts opened drop by 20%.
Previously spammers were able to easily create multiple Hotmail accounts from which to spam by having scripts automatically fill out the forms required to open a new account. HIP requires a human brain to read obscured digits from an image and retype them.
Source: Computerwire
