January 29, 2016 - HSBC customers remain locked out of internet banking into the afternoon after the bank was subject to a denial of service attack on Friday morning.

HSBC says it "successfully defended" the attack, but services are still down for many online banking customers. The downtime comes at a critical time for many customers, landing on the last day of the month and just four days before the submission of UK tax returns.

The bank says its working with law authorities to identify the attackers, but remains offline and - in an ominous note on Twitter - advises that all branches will be open on Saturday.

The latest outage comes at an unfortunate time for the bank, just days after UK parliamentarians criticised the UK's biggest banks for a string of IT glitches over the past year.

In early January HSBC chief operating officer John Hackett apologised in a video over Twitter for the two days of disruption to online and mobile banking services as UK customers returned to work in the New Year, although that was not the result of a cyber attack.

Arbor Networks' most recent Worldwide Infrastructure Security Report found that 57% of financial institutions have experienced a DDoS attack – the highest of any sector.

Richard Brown, director Emea and channel at Arbor, states: "HSBC will have to ensure that the attack was not used as a 'smokescreen', drawing the IT department's attention towards this event while sensitive data is stolen or malware is implanted in the network. "