Wisniewski notes the so-called "hacktivists" have been known to favor long weekends, holiday breaks and quiet summer days because they know there are fewer people keeping guard.

" got hacked over Christmas, got hacked over Easter," he said "When you know the IT staff is home with family enjoying a cocktail or a family dinner, it's a great time to attack."

Summer means its , including hacker conferences such as DefCon and Black Hat, both taking place in July.

"There are usually disclosures there around new vulnerabilities and that creates opportunities for people to try and exploit those vulnerabilities before companies can address them."