The chaos caused by the ransomware attack last Friday may not be over, experts are warning.
Thousands of organisations, including the NHS and private companies such as Nissan, were targeted by the attacks, which froze access to files demanding a ransom in the digital currency bitcoin to release them.
A spokeswoman for the Government’s National Cyber Security Centre (NCSC) said: “It is important to understand that the way these attacks work means that compromises of machines and networks that have already occurred may not yet have been detected, and that existing infections from the malware can spread within networks.
“This means that it is likely, in the UK and elsewhere, that further cases of ransomware may come to light, possibly at a significant scale.
Ransomware attacks are some of the most immediately damaging forms of cyber-attack.
“Our national focus must therefore be on two lines of defence.
“The first is to limit the spread and impact of the attacks that have already occurred. Due to broad government and partner efforts, a variety of tools are now publicly available to help organisations to do this.
“This guidance can be found on our homepage under the title ‘protecting your organisation from ransomware’.
“We know already that there have been attempts to attack organisations beyond the NHS. It is therefore absolutely imperative that any organisation that believes they may be affected, follows and implements this guidance.”
She added: “We have set out two pieces of guidance: one for organisations and one for private individuals and SMEs which can be applicable regardless of the age of the software in question.
“It will be updated as and when further mitigations become available and we will announce updates on Twitter (@ncsc) and elsewhere.
“Secondly, it is possible that a ransomware attack of this type and on this scale could recur, though we have no specific evidence that this is the case.
It is possible that a ransomware attack of this type and on this scale could recur, though we have no specific evidence that this is the case.
“What is certain is that ransomware attacks are some of the most immediately damaging forms of cyber-attack.”
There are easy-to-implement defences against ransomware, which very considerably reduce the risk of attack and the impact of successful attacks.
But these simple steps to protect against ransomware are not being applied by either the public or organisations as thoroughly as they should be.
Three simple steps for companies to undertake are set on the NCSC website and can be summarised as follows:
- Keep your organisation’s security software patches up to date
- Use proper anti-virus software services
- Most importantly for ransomware, back up the data that matters to you, because you can’t be held to ransom for data you hold somewhere else.
Home users and small businesses can take the following steps to protect themselves:
- Run Windows Update
- Make sure your AntiVirus product is up to date and run a scan – If you don’t have one install one of the free trial versions from a reputable vendor
- If you have not done so before, this is a good time to think about backing important data up – You can’t be held to ransom if you’ve got the data somewhere else.