Feeds

Crap PINs give wallet thieves 1-in-11 jackpot shot

What are the odds? Cambridge boffins work it out

Beginner's guide to SSL certificates

Four-digit banking PINs are almost as insecure as website passwords, according to a study by Cambridge University computer scientists.

The first-ever quantitative analysis of the difficulty of guessing four-digit banking PINs estimates the widespread practice of using a date of birth as a PIN code and other factor means that opportunistic thieves will be able to correctly guess a PIN before a card is blocked between 8-9 per cent of the time.

The researchers modeled banking PIN selection using a combination of leaked data from non-banking sources (smartphone unlock-codes and the RockYou dataset) and an online survey. The 1,300 people quizzed online were not asked for their PIN, only if it fell into one of the general categories the Cambridge University team identified.

Most people are significantly more careful choosing PINs than online passwords, with a majority using an effectively random sequence of digits. However a few weak choices – and using birthdays in particular – provide hope for opportunistic thief.

In a blog post, Cambridge University researcher Joseph Bonneau explains:

About a quarter stick with their bank-assigned random PIN and over a third choose their PIN using an old phone number, student ID, or other sequence of numbers which is, at least to a guessing attack, statistically random.

In total, 63.7 per cent use a pseudo-random PIN, much more than the 23 to 27 per cent we estimated for our base datasets. Another 5 per cent use a numeric pattern (like 4545) and 9 per cent use a pattern on the entry keypad, also lower than the other two datasets.

Altogether, this gives an attacker with six guesses (three at an ATM and three with a CAP [hand-held card] reader) less than a 2 per cent chance of success.

Unfortunately, the final group of 23 per cent of users chose a PIN representing a date, and nearly a third of these used their own birthday. This is a game-changer because over 99 per cent of customers reported that their birth date is listed somewhere in the wallet or purse where they keep their cards. If an attacker knows the cardholder’s date of birth and guesses optimally, the chances of successfully guessing jump to around 9 per cent.

If customers use their wallet then it is very likely to have a ID document with a birth date printed on it. That makes choosing a date of birth for a bank card PIN a terrible idea. Other not-so-random codes include PINs representing dates, years, repeated digits, ascending digits or ending in 69. More bad practices in the area include sharing and reusing PINs.

The researchers suggest that blacklisting the top 100 PINs can drive the guessing rate down to around 0.2 per cent in the general, though not if a user's birthday is known, where the rate stays at 5 per cent. Dropping all dates that can be considered as birthdays doesn't work because there are too many.

Even so, some blacklisting can be done. Shamefully some banks in both the US and Europe fail to prohibit obviously guessable PINs, such as 1234, the Cambridge boffins report.

The team's research paper, A birthday present every eleven wallets? The security of customer-chosen banking PINs – by Joseph Bonneau, Sören Preibusch and Ross Anderson, can be found here (PDF). ®

Beginner's guide to SSL certificates

More from The Register

next story
Knock Knock tool makes a joke of Mac AV
Yes, we know Macs 'don't get viruses', but when they do this code'll spot 'em
Shellshock over SMTP attacks mean you can now ignore your email
'But boss, the Internet Storm Centre says it's dangerous for me to reply to you'
Why weasel words might not work for Whisper
CEO suspends editor but privacy questions remain
Feds seek potential 'second Snowden' gov doc leaker – report
Hang on, Ed wasn't here when we compiled THIS document
DEATH by PowerPoint: Microsoft warns of 0-day attack hidden in slides
Might put out patch in update, might chuck it out sooner
China is ALREADY spying on Apple iCloud users, claims watchdog
Attack harvests users' info at iPhone 6 launch
NOT OK GOOGLE: Android images can conceal code
It's been fixed, but hordes won't have applied the upgrade
prev story

Whitepapers

Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
How to simplify SSL certificate management
Simple steps to take control of SSL certificates across the enterprise, and recommendations centralizing certificate management throughout their lifecycle.