Where did you download your bitcoin core.. honestly i tried to scan and here the 2 result from their exeinstall and zip file
Exe result https://www.virustotal.com/en/url/8fea1cc9947c2a98ca0877240732c7dbcb3d1f01d6ee35d313b7b0ad6089ea5b/analysis/1480269102/
Zip file result: https://www.virustotal.com/en/url/ac4e447006b7fc4085d760427d40fcf66b5b4090ed2c51144ab9bbafab27ccdb/analysis/

This one is exe and i download it from bitcoin.org but upon scanning it in virus total there is one detected
here https://www.virustotal.com/en/file/a7d1d25bbc46b4f0fe333f7d3742c22defdba8db9ffd6056770e104085d24709/analysis/

I think it is just false scan from some anti virus just like other said.. i tried to scan it in my kaspersky but there is no virus detected..