Read the ABC article carefully (as one should always do)

There's mention of a "senior official"

> senior official briefed confirmed to ABC News.

So a source in government confirmed this to ABC (who's that?). Was it just a "could be russia" type comment.

There's a separate person, who's primarily sharing the story:

> Over a dozen airport websites were impacted by the "denial of service" attack, John Hultquist, head of intelligence analysis at cybersecurity firm Mandian, told ABC News.

ABC and many news outlets generally require multiple sources prior to publishing. There's been a lot of stories lately that have the same base source, but they decide to count as "multiple sources" because an official in the government leaks to two different people and those two people confirm. It's called "information laundering"

Anyway, i'd really out of genuine curiosity know how they know this is from Russia. Which agencies are confirming this?

IMO it seems petty and not something a government would do.