The council says that its IT systems were crippled for several days after the virus infected USB stick was plugged into a PC in its housing department office on 14 May.
In its report into the incident, the council said: "At the point the memory stick was plugged in the virus attacked the host PC. It blocked connections to anti-virus and Microsoft Support websites and attempted to establish connections with 500 internet sites chosen at random from a selection of 25,000 seeking instructions from its author, and sought to also contact other similarly infected PCs that it could find. It then started propagating itself across the Ealing network."
As a result, the council was left with a bill of around £501 000 for emergency IT work and lost revenue.
The library service reported it has lost £25 000 because it could not issue fines after the virus attack and 1838 parking tickets had to be written off, losing the council some £90 000.
In a press statement, a council spokesman said: "Like many other organisations, Ealing council's computer and telephone network was attacked by a sophisticated virus."
"The council acted immediately to protect all data and ensure that essential frontline services could continue to operate."
"Costs to the council included urgent work to recover computer systems and prevent the virus from spreading."
Commenting on the USB stick virus incident, Jason Holloway, regional sales manager for SanDisk's Northern European operation, said that, although the specific virus hasn't been named, it seems certain that it exploited the Windows Autorun vulnerability to upload itself and spread.
"It underlines that fact that conventional USB flash drives have become a key method for spreading infections stealthily - as the US Army found last year", he said.
"It also shows that virus scanning has to extend beyond the PC to all types of removable storage or - better still - that employees should be issued with company flash drives that include on-board antivirus scanning."
"This ensures that users can't turn off, disable or work around the protection, and would stop these USB-borne infections from spreading."