The quality of spam is increasing and it is no longer always a scam riddled with typos. The spam now is laden with attachments, which may contain images, PDFs, documents, spreadsheets, or videosthat have malware or links to malicious sites. Peer-to-peer file sharing networks are a major source for malware, and as people download free games, music, or software, they may also unknowingly download harmful software.
In 2007, enterprise management software company CA saw a major shift to malware that is designed to capture private information such as credit card numbers, bank account contents, and gaming accounts, without the individuals knowledge. By distributing spam, spyware, and malware, the criminals can further perpetuate their activities.
A spam may contain a link to a compromised web server. When you visit a legitimate website, malicious software may be downloaded onto your computer if the site has been compromised by criminals and your browser software isnt up to date. The malware can watch what websites you visit and communicate that information to an unseen party. It can download more nasty software like spyware, a key logger, or a hijacker, CA said.
The estimated worldwide IT cost of dealing with spam had increased from $20.5 billion in 2003 to about $198 billion in 2007. According to security software developer Sophos, the major sources of spam in the July to September quarter were the US (origin of 28.4% of spam messages), followed by South Korea (5.2%), China (4.9%) and Russia (4.4%).
As per information on Wikipedia, spam has grown to about 90 billion messages a day, although about 80% is sent by fewer than 200 spammers. A report by a PineApp and Commtouch had also found spam reached up to 96% of total Internet traffic in 2007.