The U.S. Department of Agriculture is moving to block a number of social media sites from agency networks after a September 2017 memo from the Inspector General found that there had been a “significant increase” in employees accessing pornographic material on government-issued devices.

“Since 2015, the OCIO has referred 229 [Agriculture Security Operations Center] ‘network usage notice’ referrals to USDA OIG involving USDA employees and/or contractors accessing websites on government equipment which contain pornography and possible child pornography,” Ann Coffey, assistant inspector general for investigations, wrote in the memo.

“This employee misconduct is preventable, and it unnecessarily exposes USDA and its systems to significant risk. Websites which disseminate pornographic material have historically have proven themselves to be a network attack vector and, as such, present an ideal opportunity for those individuals who seek to compromise a USDA employee or contractor.”

The USDA ASOC told the OIG that it had activated a network security monitoring system in 2015 to inspect suspicious network activity in real time. Because of this system, ASOC was able to record data of “unauthorized network use” at USDA.

Chris Lowe, chief information security officer at USDA, sent a memo to staff (originally obtained by Federal News Radio) that informed them that popular social media sites, such as Facebook and Snapchat, would be blocked as of March 7, 2018.

The list includes over 400 social media sites that are not related to “official department communications or business.”

“The websites that are included in this block are attached to this message and should be reviewed to ensure official USDA business and communications is not impacted. We have worked with the Office of Communications to ensure this list does not conflict with official USDA channels of communication, however, we ask that you review to check for impact to your mission areas and agencies,” Lowe wrote.

According to the September 2017 memo, USDA already employs the Department of Homeland Security’s Einstein 3A software, which uses in-line, network-based cyber monitoring to protect agency systems. This monitoring, however, apparently failed to block employee access to pornographic sites.

“USDA continues to actively work to ensure appropriate usage of government resources as part of meeting Secretary Perdue’s commitment to making USDA the most efficient, most effective, best managed department in the federal government,” a USDA spokesperson told Federal Times.