Twitter users in Japan have been warning of a growing number of messages with embedded links that cause mobile and PC browsers to display taunting messages and freeze.
The URLs appear to cause no lasting damage to their target and pose no security risk.
Many on Twitter posted warnings through the weekend Monday in Japanese not to click on the blog invites. Older tweets included messages asking how to restart their frozen browsers.
In a blog posting Friday, Tokyo-based security firm Trend Micro said it had first identified the URLs, which it calls "browser crashers," in April of last year. But it said they had spiked in recent weeks, with the company identifying 300 cases from March 7 through March 19.
The company referred to a Japanese case in 2011 where a user was arrested for making a popular chat site unusable using similar code. It said the current wave of URLs affect browsers in Windows, Android and iOS.