Earlier this year, a report from CNET explored the current state of ad blockers. Among the data cited within was a study from the software company Blockthrough, which estimated that 40% of adults in the United States make use of some ad-blocking technology. That might not come as much of a surprise to you — but another recent report at Vice offers a fascinating window into some of the people and organizations utilizing ad-blocking technology.

In the Vice article, Joseph Cox covered the way the U.S. intelligence community has begun making use of ad-blocking technology. That includes the CIA and the NSA, among a number of other agencies. Last week, Senator Ron Wyden wrote a letter to the Office of Management and Budget calling for them “to protect federal networks from foreign spies and criminals who misuse online advertising for hacking and surveillance.”

Wyden cited guidelines from both the NSA and the Cybersecurity and Infrastructure Security Agency recommending that ad-blocking software be used. Wyden goes on to quote the Chief Information Officer from the Intelligence Community, who stated, “The IC has implemented network-based ad-blocking technologies and uses information from several layers, including Domain Name System information, to block unwanted and malicious advertising content.”

A report from CrowdStrike published earlier this year warned of the dangers of “malvertising” — which has cropped up on legitimate websites, and has been used to give control of computers and mobile devices to a third party. That’s alarming enough in its own right, so it’s not hard to see why people dealing with classified information would be especially worried. Will Wyden’s letter find a welcome response? It could be the difference between an ordinary day and a crisis waiting to happen.