
The research reveals that in total, 304,000 web pages hosting malicious code were identified in 1 May.
According to the research, the most prominent web-based malware last month was Iframe, accounting for almost two-thirds of all the web-based threats.
Iframe works by injecting malicious code on to legitimate websites, the anti-virus company said.
“Attacks spreading on the web are becoming more frequent and more problematic for businesses every month,” warned Carole Theriault, senior security consultant at Sophos.
“The real nasty attacks are most often found lurking on legitimate web pages," she added.
"This is a wake up call for organisations with a website, being out of date with patches and running inadequate security has very real risks."
The research also found that China continues to host the most infected web pages, with more than half (53 per cent) of malicious web pages found in the Asian country.
China’s dominance can be attributed to increased reports of Iframe, which has been widely detected on unprotected web pages in the country, according to the research.