Empty spam, PDF spam emerged

After a period of raging, the number of spam images has decreased in recent weeks. But at the same time, a new type of spam emerged, with PDF attachments to entice users to buy shares of a certain company.

" Decline in spam is because security companies have quickly adjusted their products. If it was easy to get through spam filters before, they are now blocked at a decent rate." High, "said Paul Henry, vice president of Secure Computing technology.

In the past, the reason that spam images tricked the filter was because the contents of the email were embedded with an image. This trick makes the filter - which relies on nonsensical combinations or appear in spam to determine what is legitimate email and what is unwanted email - that can't be decrypted.

In early 2007, the number of spam images accounted for more than half of the total spam circulated on the network. But starting from July, they only accounted for 38% and are now down to just 19%.

Data from Symantec also yielded similar conclusions. Accordingly, the amount of spam images began to decline from May, continuously until this time.

" Anti-spam software, black lists and filters have done a great job of them. Now it's time for hackers to find a new direction to make it difficult for the security world ," Symantec predicts.

This wave has not passed, another wave has arrived

Source: CNN Begin to take the place of spam images as PDF spam, spam that spammers use PDF attachments - the format that most filters cannot read. Its content is convincing people to buy stocks.

So far, new security companies have recorded 2 types of PDF spam: One looks very professional, in the form of newsletter and has spread to . 5 billion times within the first few days. The second type looks simpler, with content praising a German stock.

" Within the last 10 days of June, the second category was sent to more than 30 million users, " Symantec said.

Because of the new appearance, spam PDF can not reach the "peak" amount like image spam. As of early July, they only accounted for about 4% of the total spam sent - however, it is clear that its malicious and sophisticated level is much higher.

" Spam PDF shows that spammers are constantly creating and improving their techniques. The battle between spammer and security is always cat and mouse. The anti-smart tool, the spammer is creative 10 ", she Sharon Finney, Director of Information Security for Dekalb Medical Center said.

Trong Cam