The parent company of Ogilvy, Cohn & Wolfe, H+K and others confirmed on Twitter at just after 3pm UK time that the suspected attack was affecting "several WPP companies", and said it was "taking appropriate measures" and would provide updates.
Click here for Sir Martin Sorrell's response to the WPP cyber attack
IT systems in several WPP companies have been affected by a suspected cyber attack. We are taking appropriate measures & will update asap.— WPP (@WPP) June 27, 2017
The same statement was posted on Facebook, where one commentator asked: "Can you confirm if this is the ransomware attack affecting various organizations today?"
The BBC reports that WPP is "among dozens of firms reporting problems", with apparent ransomware strikes also affecting Ukraine's state power distributors and the main airport of the country's capital, Kiev. The corporation also lists Russian oil producer Rosneft and Danish shipping company Maersk as victims of the attack.
A spokesman for London-headquartered WPP reiterated the social media statement. He said: "IT systems in several WPP companies have been affected by a suspected cyber attack. We are assessing the situation, taking appropriate measures and will update as soon as possible."
The spokesman declined to give further details.
Whole global WPP company is hacked, literally standing around with nothing to do pic.twitter.com/juA0129oIz— Rich (@rbrack10) June 27, 2017
WPP's website was unavailable this afternoon, initially with a statement saying: "The WPP web site is currently unavailable due to important routine maintenance normal service will resume shortly. We apologise for any inconvenience this may cause. In the meantime if you would like to contact WPP, please email the site Editor at the following address: email@example.com."
UPDATE: An hour after confirming the attack on Twitter, WPP issued a statement via the London Stock Exchange's RNS feed stating that "some of its information technology systems have been affected by a global cyber attack".