[clug] fraud

[peter]

There was a short article recently about a person who had a bathroom 
renovation done, costing $11500. On completion, the builder emailed her 
a bill, which she paid via bank transfer. Builder didn't receive the 
money. Apparently the bank details on the builders email had been 
changed by a scammer.  Has anybody on CLUG seen anything like this 
before?  Can you explain how the scam could be implemented.... virus, 
malware etc ?

TIA

Pete