/usr/aarch64-linux-gnu/lib/libasan.so.5 is in libasan5-arm64-cross 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/aarch64-linux-gnu/lib/libasan.so.5.0.0
/usr/aarch64-linux-gnu/lib/libasan.so.5.0.0