A woman in her 60s says she has been left “traumatised” and “frightened” after oil was thrown over her house and car.
Sally Ley, who lives in East Harling, Norfolk, with husband Jon, said she had no idea why their home was targeted.
Two males threw oil at their White Hart Street property causing thousands of pounds of damage.
Norfolk Police said it would like to speak to anyone who saw a white pick-up lorry in the area at the time.
The vandalism happened at 01:00 on 31 October, but police have only just notified the media about the case.
Mrs Ley said she did not believe it was a Halloween prank, but police have not commented.
Oil was spattered up to the eaves, down the windows and poured over her husband’s car, Mrs Ley said.
“It’s a big sticky mess and despite a cleaning company coming in straight away, it is still seeping in through the front door letter box and the windows,” she said.
Mr and Mrs Ley, who are pensioners, moved to the property four years ago.
Their CCTV camera captured “fuzzy images” of a van driving past several times, with Mrs Ley adding that “two people came up the driveway, with two buckets each and hurled them”.
The substance washed off their car, causing no long-term damage, but the driveway remains badly stained.
“The cleaning company has yet to identify the substance used in the incident – they don’t know if it’s flammable so have not been able to tackle the stains on the drive,” explained Mrs Ley.
She said it could take “several weeks of treatment”, but the stains may still not be removed and some of the drive may need replacing.
“[We’re] frightened, shocked, we’ve no idea why we were targeted, it’s very scary,” said Mrs Ley.
Police have appealed for witnesses.