About 25 percent of IT managers cannot identify the majority of their network traffic, according to a new survey.

Sophos’ just released The Dirty Secrets of Network Firewalls found that 25 percent of those asked could not identify 70 percent of the traffic on their networks and the majority of IT managers cannot even identify 45 percent of the traffic. This lack of visibility is a huge concern and needs to be corrected, said John Shier, Sophos’ senior security advisor.

“They don’t know if it’s Spotify, something legitimate or a cryptocurrency miner, he told SC Media at RSA 2018.

The good news is the majority, 84 percent, of the 2,700 people surveyed agreed this lack of visibility is a critical issue.