Google has removed two extensions from its Chrome web browser after they were found to have been converted to malware. Chrome extensions Add to Feedly and Tweet This Page were simply innocent browser apps until they were purchased and used to feed users advertisements.

First picked up by OMG Chrome and Ars Technica, some users allege that the practice of turning popular extensions into adware is by no means new, nor is it restricted to the two banned apps. Add to Feedly’s creator Amit Agarwal described in a blog post how he was given “a four-figure offer” for the simple program, which had 30,000 users. Not expecting his extension to be turned into adware, Agarwal unsuspectingly sold to program to advertisers.

Google took action against the two offending apps as soon as the news broke on the internet, banning the illegal extensions from the Chrome store. This may not be the last time that Google is forced to remove extensions from Chrome due to adware contamination; last week the developer behind popular app Honey claimed that he was also approached about selling his add-on to advertisers.