An NDR (non-delivery report) is an email automatically sent by mail systems to advise senders of problems delivering their messages.
These messages are usually legitimate, but this mail server function is being exploited by spammers to distribute spam, using the sender's real name. The spam content is usually sent as an attachment to the fake non-delivery notice. Although in most cases users have not sent the supposedly undelivered email, they still become curious and open it.
According to Luis Corrons, technical director of PandaLabs, "there is presently no consensus on whether NDRs are a technique to evade anti-spam filters or a collateral effect of dictionary attacks; either way, this technique is now among the most widely used. These waves of spam are usually generated through botnets (infected PCs controlled by attackers to launch spam, etc.). Since most NDRs are legitimate emails and, part of the mail server functionality, many traditional anti-spam techniques did not detect or block them up until now".
Panda Security's perimeter and corporate network security solutions include specific technologies for this type of spam. More information: http://www.pandasecurity.com/enterprise/solutions/security-appliances/
About PandaLabs Since 1990, its mission has been to detect and eliminate new threats as rapidly as possible to offer our clients maximum security. To do so, PandaLabs has an innovative automated system that analyzes and classifies thousands of new samples a day and returns automatic verdicts (malware or goodware). This system is the basis of collective intelligence, Panda Security's new security model which can even detect malware that has evaded other security solutions.
Currently, 99.4% of malware detected by PandaLabs is analyzed through this system of collective intelligence. This is complemented through the work of several teams, each specialized in a specific type of malware (viruses, worms, Trojans, spyware, phishing, spam, etc), who work 24/7 to provide global coverage. This translates into more secure, simpler and more resource-friendly solutions for clients.
More information is available in the PandaLabs blog: http://www.pandalabs.com For more information: [email protected] Tel. +34 91 806 37 00