Spammers Exploit NDR to Send Mass Phony E-mails

According to a research completed by computer security researchers, 90% of e-mails arriving at company inboxes are spam, while spammers use a number of ways to elude spam filters adjusted in the anti-spam systems.

Also, as researchers themselves defined, spam, which used to be chiefly text-based, has now changed into e-mails with embedded images and attach common file types such as Excel documents and MP3s that help spammers to gain access to the users' mailboxes.

Researchers at McAfee Avert Labs commented that the latest choice of the spam criminals is the 'Non-Delivery Report' (NDR) spam. In May 2008, McAfee said in its monthly report that NDR spam then accounted for about 2% of the entire spam and that it had been 4% less than the amount observed two weeks earlier.

Describing NDR, researchers said that users get NDRs when a particular e-mail does not come to a person's address and a notification is dispatched to the e-mail's sender. NDR spam is classified into three chief categories, an NDR containing the complete message, an NDR containing just the spammy titles, and an NDR without any spam at all. Nevertheless, there could be a significant increase in NDR activity thanks to spammers who send their junk e-mails widely.

Interestingly, while some NDRs are authentic, others are phony, and are used for generating NDR messages by changing the 'From' address to replace it with a genuine domain sender.

Describing the NDR-type of spam as the most damaging, researchers said that it is necessary to take action otherwise e-mail servers could be flooded with irrelevant e-mails leading to drainage of resources and slow down of performance.

Hence, according to security analysts and researchers, the most effective way to prevent NDR spam is to use anti-spam solutions that would detect spam in NDRs and subsequently delete them.

Meanwhile, GFI Software has introduced a 'White Paper.' The paper explains the nature of NDR spam and the way administrators can adopt effective measures for reducing its impact on their respective e-mail servers, as reported by SECURITYPARK on June 13, 2008.

Related article: Spammers Continue their Campaigns Successfully

» SPAMfighter News - 6/27/2008