Customers of PNC Bank were sounding increasingly frustrated Wednesday as problems continued to arise in accessing their accounts online, preventing them from checking balances, paying bills or performing other transactions using the Pittsburgh bank's website.
The bank's latest interruption in service came a little more than a week after federal regulators issued an alert to the nation's banking community urging top executives to be prepared for denial-of-service attacks and to evaluate their processes for dealing with cybercrimes.
"How much longer are customers supposed to be expected to put up with this before there is a mass exodus?" one customer posted on PNC's Facebook page Wednesday morning.
Another wrote: "So I called PNC ... Was advised if I need to pay bills that I should send out checks. WTH! That's the best solution PNC has. Don't waste your time calling and sitting on hold."
Those comments were among dozens posted on the social media website by disgruntled customers over the last two days.
For its part, PNC posted an apology and urged customers to keep trying to log in or to send the bank a private message on Facebook with a contact number. "Our team will be in touch to assist," the bank said.
PNC spokesman Fred Solomon did not return phone calls seeking comment.
"Our systems are operating normally," Mr. Solomon said in a brief email late Wednesday afternoon. "We are responding to the individual customers who expressed concern today."
This week marked the fourth in a row that customers of Pittsburgh's biggest bank reported intermittent problems accessing their accounts.
Problems began Dec. 11 after a group called the al-Qassam Cyber Fighters threatened a round of denial-of-service attacks against PNC and a handful of other big banks by flooding their websites with communications requests. The group has said it is seeking the removal of an anti-Islamic YouTube video from the Internet.
The December threat came on the heels of a similar threat against big banks in September when PNC's online operations were disrupted for several days.
The hackers "just pummeled us," CEO James Rohr told CNBC following the September incident, adding that no customer data were compromised. PNC "had the longest attack of all the banks," Mr. Rohr said.
"Banks need to have a heightened sense of awareness regarding these attacks and employ appropriate resources to identify and mitigate the associated risks," said the alert issued in late December by the Office of the Comptroller of the Currency.
In some cases, denial-of-service attacks are used to "distract" bank personnel and technical resources so thieves can gain access to customer accounts, the alert said.
The OCC said banks should "provide timely and accurate communication to their customers regarding website problems, risks to customers, precautions customers can take and alternate delivery channels that will meet their banking needs."
For the full OCC alert, visit www.occ.treas.gov/news-issuances/alerts/2013/index-2013-alerts.html.
Patricia Sabatini: firstname.lastname@example.org or 412-263-3066.