Heartbleed bug: Am I at risk? Do I really need to change my password?

The encryption flaw described as 'catastrophic' by experts has rocked the web, read on to find out which sites and services are affected - and what you can do

The bug could have compromised the safety of more than two-thirds of the web

The discovery of Heartbleed, a flaw in one of the most widespread encryption standards used online, has panicked webmasters and users alike.

The bug has gone unnoticed for more than two years and could have potentially given hackers access to an unlimited array of secure data – everything from passwords and login details to credit card numbers and addresses.

Although it’s difficult to say exactly how many websites have been exposed, the lower estimates are around 500 million with a large number of major web companies (Google, Facebook, Yahoo, etc) all forced to update their software to protect against the bug.

However, there have been quite a lot of mixed messages as to whether or not users should change their passwords, with some outlets urging that you should create new ones immediately while others are advising that you wait.

To add to the confusion there’s also been reports of hackers sending out phishing emails related to Heartbleed - in order to trick users into giving up passwords that have yet to be compromised. Be on the look out for these and don't follow any links in suspicious looking emails - if you want to change a password go to the site directly.

The Heartbleed bug: Because now software flaws come with their own logos

Which sites are affected?

Most Google sites and services (including Gmail and YouTube - but not Chrome) were affected, as were sites maintained by Yahoo (including Tumblr and Flickr). Facebook was also hit by the bug although Twitter and LinkedIn were not.

Other big sites that have confirmed that they weren’t affected include Amazon, Hotmail and Outlook, eBay, PayPal and all of Apple’s properties – including iCloud and iTunes. If you want to check whether or not a site you use is still affected then you can do so here – just enter the URL.

Another big worry is for online banking, but thankfully we have some good news in that department. Lloyds, HSBC, RBS, Natwest, Santander and the Co-Op have all confirmed that they were not affected by the bug (they were using different encryption standards). Barclays has yet to issue a statement.

However, this does not mean that your credit card details are completely safe – as they could have been compromised via your Gmail or another third-party site. The security of mobile banking apps is still a developing situation as well.

Gmail was among the sites affected.

So do I need to change my passwords?

In a word: yes. For the sites we’ve listed above as being affected (including Gmail, Yahoo, Tumblr, Flickr, Facebook) it definitely won't hurt to change your password some time in the next couple of weeks.

Although security experts have warned that you shouldn't be too quick to change passwords, this is because not all website have patched their servers and changing your password before this happens could make matters worse. The sites we've listed above have patched their servers and if you want to check one we've not mentioned - click here and enter the URL.

Unfortunately, some sites (including Google) have specifically said that users don't need to change their passwords. While it's true that some sites are confident that they fixed the bug a while back, as most of us are guilty of changing our passwords less frequently than we should do (aka never) we think that this is as good an opportunity as ever to be a bit more security-conscious.

If you can't remember your password, trying leaving a subtle hint. (REUTERS/Kacper Pempel)

What should my new password be?

In lists of the most frequently used passwords online there’s some obvious clangers that we know you’re too smart to use (these include old stand-bys such as ‘123456’ and ‘password’ itself) but just because a password doesn’t look obvious to you that doesn’t make it safe.

This means that you shouldn’t really use any single words that are found in the dictionary, any words connected to you (place of birth or pets' names), nor should you use any obvious ‘substitutions’ (eg pa55w0rd- more complicated variations are required) or patterns derived from your keyboard layout (eg ‘1qaz2wsx’ or ‘zxcvbnm’).

It’s wise to use a variety of characters in your password (including upper and lower case as well as numbers) but an easy way to get more secure is to start thinking of your password as a passphrase.

The easiest way of increasing the difficulty of a password is by simply making it longer – so try combining multiple words together and then adding in numbers between them.

You could pick a number of some significance to you (for example a loved one’s birthday, ie 12/08/1970) and then splicing this with a nonsensical phrase (‘shoesplittingwatchwizard’) to get a suitably difficulty password: Shoe12Splitting08Watch1970Wizard.

Other suggested methods for making a strong and memorable password include taking a sentence or a favourite line from a song as a starting point. So you might take the line "When you call my name it's like a little prayer" and turn it into wuCmNilaLP. Madonna is optional of course, but we think this a fun method - especially if you can work in numbers somewhere.

You should also use different passwords for your different accounts (perhaps the most difficult piece of advice to follow of all) and if you want to be really secure you should also set up two-step authentication where available.