Cyber attacks are fundamentally weird. Moving through shared information networks, adversaries cross once-impenetrable oceans to play around with files and systems on distant computers, hoping to steal information or cause harm. It's a haphazard jumble of espionage, sabotage, and hacking, and it can take years to figure out that an attack took place, and who did it. Next week, the Obama Administration plans to identify Iran as the cause of a 2013 attack on New York's Bowman Avenue Dam, CNN has learned from officials familiar with the investigation.

The Wall Street Journal first reported revelations of the attack in December 2015:

Hackers are believed to have gained access to the dam through a cellular modem, according to an unclassified Homeland Security summary of the case that doesn't specify the type of infrastructure by name. Two people familiar with the incident said the summary refers to the Bowman Avenue Dam, a small structure used for flood control near Rye, N.Y. Investigators said hackers didn't take control of the dam but probed the system, according to people familiar with the matter.

The dam is just 20 miles from New York City, and it's a modest structure made of concrete that's just 20 feet tall. It blocks a small brook. By all appearances, it seems that while that hackers were able to get into some computer systems associated with the dam, they weren't able to access anything important, or do any damage.