The hack, which happened on Wednesday morning, may have seen the sensitive personal data of millions of customers stolen.
So far Dido Harding, the company’s chief executive, has been unable to say whether the information had been encrypted.
She has apologised to customers who are now at risk of having their credit card and bank details used by the criminals behind the attack.
“I am, in a sense, saying that there is a risk that all of our customers’ personal data has been accessed and therefore we are taking that very seriously and looking to make sure that we can help our customers protect themselves if that data has been stolen,” she told BBC Radio 4′ Today programme.
Customers would be given free credit monitoring to check if their identity had been cloned and said everyone with a TalkTalk account should assume their information is at risk, she said.
Senior police have repeatedly singled out cyber crime as one of the key challenges facing law enforcement agencies in the present and the future.
The capacity of authorities to combat the danger posed by hackers to the country’s infrastructure could come under scrutiny as forces brace for fresh budget cuts next month.
Michala Hart, the head of channel strategy at cloud computing firm Exponential-e, said no individual or business is ever completely safe online.
“Once again, this latest attack shows that it’s not a matter of if you’ll be hacked but when.”
Read our tips about how to protect yourself in the wake of the TalkTalk hack here.