Google said Tuesday that fake software security programs rigged to infect computers are a growing online threat, with hackers tricking people into installing nefarious code on machines.

An analysis of 240 million web pages by the internet search giant during the past 13 months revealed that fake anti-virus programs accounted for 15 percent of malicious software it detected, AFP reported.

"The Fake AV threat is rising in prevalence, both absolutely and relative to other forms of web-based malware," Google said in its findings.
"Clearly, there is a definitive upward trend in the number of new Fake AV domains that we encounter each week."

Fake anti-virus (AV) peddlers rig websites to frighten visitors with pop-up messages warning that supposed scans have found dangerous malicious software on machines. The scam goes on by selling victims programs that hackers claim will fix the purported problems -- but which in fact usually plant nefarious computer code on machines.

Such transactions can also leave credit card information in the hands of cyber crooks.

"Surprisingly, many users fall victim to these attacks and pay to register the Fake AV," Google said. "To add insult to injury, Fake AVs often are bundled with other malware, which remains on a victim’s computer regardless of whether a payment is made."

Google has refined tools to filter out booby-trapped websites and hackers have evidently responded by flitting from one domain name to another.

The Google study was presented at the Usenix Workshop on Large-Scale Exploits and Emergent Threats in California, and analyzed websites between January 2009 and February 2010.