Thousands of websites in Israel were hit by a cyberattack on May 21 and knocked offline or defaced with anti-Israel messages and videos.
The hackers are said to accessed the sites using a vulnerability in the servers of Israel's biggest website hosting company Upress.
There were conflicting reports regarding the identity of the perpetrator of the attack, with some saying it was carried out by Iran as part of its war against Israel in the cyber domain. However, others said Hamas in Gaza was responsible.
Israel's National Cyber Directorate said it received reports of the attack and was dealing with the issue. It urged anyone who logs onto one of the affected sites not to click on any links shown.
In a statement, Upress said it identified an intentional and wide-scale attack by Iranian entities that had been enabled by a vulnerability in the Wordpress website-building software. Upress also emphasized that the sites and data of its clients were backed up in its systems, and that the company was working intensively to fix the damage to all of the sites as soon as possible. According to later reports, Upress took down all the sites and removed the file the hackers were exploiting.
The affected sites included city halls, restaurant chains and NGOs.
Information security company ESET said in a statement that based on past cases, hackers use two main types of attack: either defacement or Distributed Denial of Service (DDoS), namely making a site unavailable by overwhelming it with traffic. The latest incident appears to be the continuation of attacks by a group of anti-Israel hackers against the country's institutions and sites, according to the company.