Zscaler, the security-as-a-service platform provider, has detailed an ongoing spyware attack from sites running the popular WordPress content management system and blogging software.

The firm’s ThreatLabZ team said that the attack has being active since the first week of August, resulting in "over 20,000 security events to date from over 2,000 web pages."

Infected websites have Javascript injected into their code, which results in them downloading unwanted programmes. WordPress was attacked earlier this year via malicious code in a plugin, which sent victims to an exploit kit.

In one case observed by the ZScaler researchers, users were prompted to update Adobe Flash player. If the victim allows the download goes ahead, once the unwanted programmes have been dowloaded, victims are told their Adobe update has failed and are sent to the legitimate website.

During the download of Adobe Flash, users might also be prompted to dowlonad Windows 7 PC Repair. Other examples of software used in the attack included MediaDownloader, and NewsTabTV plus on Google Chrome.

WordPress is just the latest target, as attacks on popular websites continue at pace. The adult website xHamster.com, which attracts nearly half a billion users a month, was recently the victim of a malvertising attack.