The FBI has begun investigating the hack of a number of websites – including the site of Dublin Rape Crisis Centre – by pro-ISIS script kiddies.

The Dublin Rape Crisis Centre in Ireland was defaced so that its home page featured the black ISIS flag and the message "Hacked by ISIS, we are everywhere." A Flash audio plug-in planted on the page as part of the same hack played an Arabic song.

The site was returned to normal operation by Monday morning with a tweet from the official Dublin Rape Crisis Centre blaming the assault on a "WordPress hack" that didn't target it specifically.

Ellen O'Malley-Dunlop, chief exec of the Rape Crisis Centre, described the hack on Sunday as "sinister", and apologised to visitors for any alarm they may have felt when confronted by the unexpected imagery.

"We are concerned that any victims who came to our site looking for help may have seen it... it was very distressing," O'Malley-Dunlop told the Irish Independent.

"It was a WordPress hack. WordPress are aware of it. They've updated us, made us more secure and given us new passwords," she added.

The timing of the hack coincided with International Women's Day on Sunday.

The same act of vandalism also affected a number of seemingly unconnected US sites. Pages including those of Eldora Speedway, a site owned by NASCAR star Tony Stewart, a church in Canada, a Goodwill Centre in St. Louis, Missouri, the Sequoia Park Zoo in Eureka, California and several bars were all targeted for defacement. Southwest Montana Community Federal Credit Union's site was also hit in the same run of attacks over the weekend.

The credit union's chief executive, Tom Dedman, told NBC that the site was temporarily offline pending a security inspection. There's no evidence at this stage that any account information was compromised. The credit union's swmcfcu.org site is back online at the time of writing on Tuesday morning.

The defacements appear to be opportunistic rather than targeted and the motive probably traces back to attention-seeking rather than ideological affinity to ISIS/ISIL. The skill level looks to be set no higher than searching the interwebs for vulnerable WordPress installs and spraying digital graffiti on them using a pre-written tool. No skill – much less coding chops – would have been needed in this scenario.

"The FBI is aware of the reported incidents and is contacting the impacted parties," the FBI told NBC. ®