MessageLabs have found via recent scanning of customers' email that one or two unique Trojans have emerged each week which never reappear. "These are not mass mailers-they are packed and encoded uniquely, and are usually one-off occurrences," said Sunner. From historical data MessageLabs then found that these unique one-off Trojans have appeared regularly over the last 13 months.

MessageLabs looked into Trojan statistics gathered after a recent incident of a custom-Trojan being used in Israel to snoop and spy on various companies resulting in the arrest of two people involved in widespread fraud.

These threats did not only target larger companies, which is the common belief. "Companies of all sizes and industries were the targets for these unique threats," Sunner said.

Decoding the stats

At Hong Kong-based security firm Network Box, the belief is there are more reports on the topic of targeted attacks recently, "but we've seen no first-hand examples in Asia or Hong Kong yet," said Mark Webb-Johnson, CTO at Network Box.