After 'Zoom bombings', other incidents, FBI warns of videoconferencing hijacking amid coronavirus The FBI highlighted two incidents in Massachusetts related to Zoom.

As more Americans rely on videoconferencing for work and to keep connected to love ones amid the novel coronavirus pandemic, the Federal Bureau of Investigation is warning of potential hijacks of videoconferencing applications.

Overnight, the FBI highlighted two incidents in Massachusetts related to the popular videoconferencing app Zoom.

"In late March 2020, a Massachusetts-based high school reported that while a teacher was conducting an online class using the teleconferencing software Zoom, an unidentified individual(s) dialed into the classroom. This individual yelled a profanity and then shouted the teacher’s home address in the middle of instruction," a release from the Boston FBI Field Office said. "A second Massachusetts-based school reported a Zoom meeting being accessed by an unidentified individual."

The statement continued, "In this incident, the individual was visible on the video camera and displayed swastika tattoos."

Brad Garrett, a former FBI agent, said Zoom has been a rich target for cyber criminals and malicious actors.

"Cyber criminals are targeting video conferencing sites like Zoom, particularly during the COVID-19 pandemic," Garrett, now an ABC News contributor, said. "Typically they create domains that impersonate Zoom, with the goal of stealing personal information."

He noted that because about 60% of Fortune 500 companies use apps like Zoom, cyber criminals see an opportunity to potentially steal corporate proprietary information and sensitive information about employees.

"As more schools and businesses work remotely, this creates an ideal environment for cyber thieves," Garrett said.

Advocacy groups have been calling for Zoom to take action against what they allege is trolling of African American users on the platform.

Dennis Johnson, a doctoral student at California State University, Long Beach, was presenting his dissertation via Zoom last week as per the school's COVID-19 contingency plans. In the middle of his dissertation he said a hijacker gained control of his presentation and interrupted it by posting pornographic images and typing a racial slur on screen.

"Honestly, I was just lost -- I reached out to Zoom and they tell me these are 'party crashers.' These are not party crashers, they are racist, sexist attacks on people of color," Johnson alleges.

"This week, one of our members, Dr. Dennis Johnson was defending his dissertation via the Zoom platform when a racist troll hijacked his presentation -- drawing crude images ... on the screen," Brandi Collins-Dexter, Senior Campaign Director Color Of Change wrote in a letter to executives at Zoom.

The FBI offered some tips to people who are working from home – especially using apps like Zoom. They said to make sure everyone’s software is updated, not to make meetings or classrooms public and to provide the link directly to people.

In a statement, Zoom told ABC News that they urge people to report incidents on their website and they will take appropriate action.

"We take the security of Zoom meetings seriously and we are deeply upset to hear about the incidents involving this type of attack. For those hosting large, public group meetings, we strongly encourage hosts to review their settings and confirm that only the host can share their screen," a Zoom spokesperson said in a statement.

"For those hosting private meetings, password protections are on by default and we recommend that users keep those protections on to prevent uninvited users from joining," the statement said.

What to know about coronavirus:

How it started and how to protect yourself: coronavirus explained

What to do if you have symptoms: coronavirus symptoms

Tracking the spread in the US and Worldwide: coronavirus map

ABC News' Samara Lynn contributed to this report.