Spam and virus attack rates in the UAE increased this month while globally they showed a decrease, according to a report.

Spam rate in UAE increased to 91 per cent in September from last month's 85.3 per cent, while globally it decreased from 88.5 per cent to 86.4 per cent.

The global ratio of email-borne viruses in e-mail traffic from new and previously unknown bad sources was one in 399.2 e-mails (0.25 per cent) in September, a decrease of 0.09 per cent since August. In the UAE, it was at one in 351.8 e-mails, while last month it was one in 228.7 e-mails.

These figures were published in the September and Q3 2009 MessageLabs Intelligence report by Symantec.

Analysis highlights that botnets are now responsible for sending 87.9 per cent of all spam. A newer botnet, Maazben, has experienced rapid growth since its infancy in late May mainly sending out casino-related spam while Rustock, one of the oldest and largest botnets, has doubled in size since June and established a predictable spamming pattern.

According to MessageLabs Intelligence, Maazben's growth has accelerated during the past month from 0.5 per cent of all spam in August to 1.4 per cent of all spam in September. Rustock is the largest in terms of number of bots at 1.3 to 1.9 million bots but has kept its output per bot relatively low. In addition, Rustock has settled into a predictable spam pattern beginning everyday at 3am Eastern Time, peaking at 7am ET and ceasing spamming at 7pm ET. It then rests for eight hours before beginning again.

Rustock is the only botnet with a regular spam cycle. One of the most dominant botnets, Rustock is responsible for ten percent of all spam. As such, its spam pattern is reflected in overall total daily spam patterns.

"Over the past year, we have seen a number of ISP's taken offline for hosting botnet activity resulting in a case of sink or swim and an ensuing shift in botnet power," said Paul Wood, MessageLabs Intelligence Senior Analyst, Symantec. "This has undermined the power of the more dominant botnets such as Cutwail and cleared the way for new botnets like Maazben to emerge.

"However, this won't always be the case as botnet technology has also evolved since the end of 2008 and the recent ISP closures now have less of an impact on resulting activity as downtime now only lasts a few hours rather than weeks or months."