The company claims to have reduced the infection rate on its 30,000 client PCs, from 30,000 cases a month to between 100 and 200 cases.
The improvements follow its decision to replace Dr Solomon anti-virus software with a system from McAfee, which, for the first time, allows it to manage virus protection on 30,000 desktops and 5,000 servers centrally.
The system allows Halifax to immunise its PCs and servers against new virus variants within 12 hours, compared to more than a week with the Dr Solomon system, said Richard Fry, malware [malicious software] defence team leader at the bank.
"Administration overheads have been reduced by 75% because we have cut down the amount of work our software team has to do to get new virus signatures out.
'Now it is at the touch of a button. Before it meant packaging up the signature into our standard software, putting it on test rigs, testing that the distribution works, then distributing that to all servers, and it would take nearly a week," he said.
The bank used the new facility to protect itself against the recent Badtrans virus. "It meant we had zero infection and zero propagation," said Fry.
The system has enabled Halifax to define a company-wide anti-virus policy, which specifies what files should be scanned and how often virus scans should occur.
It also provides Halifax with an audit of the level of anti-virus protection on each PC and an indication of whether virus software needs to be updated.
The bank can also monitor the re-infection rates on each PC, and to identify users who may be repeatedly infecting their machines.
"We can target our limited resource to educate the users who are repeat offenders. If you get the same person bringing in infected discs week after week, you can go to that person," said Fry.
Halifax began to review its anti-virus software after supplier Network Associates announced that it would end support for the bank's Dr Solomon anti-virus software, two years ago.
It chose to replace the system with McAfee because of its infrastructure management capability, and its use of the Dr Solomon anti-virus engine, which Halifax sees as well-proven.