Generally, the amount of spam containing malicious attachments hovers around 0.5 percent of all spam, with occasional brief spikes every two to three months, Morss said. Since mid-September, however, malicious attachments have been present in approximately 1.3 percent of all spam on average.
The amount of spam containing malware increased ninefold during September over the previous month, Symantec said in its report.And at one point in September, malware was present in 4.5 percent of all spam, the Symantec report said.
In a reflection of the report, the FBI this week issued three different warnings about fraudulent email campaigns currently making the rounds, all of which contain malicious attachments. Some of the emails seem to be coming from the FBI and contain attachments for what those behind the messages claim are reports related to weapons of mass destruction or Al-Qaeda financing.
Other fraudulent emails making the rounds are spoofed to look like they were sent by U.S. Department of Justice and contain attachments of a supposed audio file with speech from Osama Bin Laden directed at the people of Europe, the FBI said.The FBI does not send unsolicited emails and if users encounter these messages, they should not click on the attachments as they likely are viruses or other malicious software, the FBI said.