In addition to using Facebook, Twitter, and messaging apps such as Telegram, Islamic State is also distributing custom communications software to spread its message of radical Islam.

The militants have developed a smartphone app designed to run on Android phones that is available to download in private channels on Telegram, an encrypted smartphone chat program. According to security experts tracking the group, the app appears to be a new effort from Islamic State (IS) to bypass often less secure social media platforms that are easily targeted and attacked by governments and independent groups working to blunt the group's digital presence.

"They want to create a broadcast capability that is more secure than just leveraging Twitter and Facebook," says Michael Smith II, chief operating officer at Kronos Advisory, a defense consulting firm. “IS has always been looking for a way to provide easy access to all of the material.”

Mr. Smith says the app was discovered by Ghost Security Group, an independent collective that gathers information about IS online activities. Smith says that he works as a liaison between Ghost Security and American counterterrorism officials.

After the attacks in France last month, new reports began surfacing about the tools and technologies that IS militants favor to communicate with each other as well as to lure recruits to the front in Syria and Iraq. The New York Times reported that militants used encryption technologies in the lead-up to the coordinated Paris strikes. Initial reports of IS encryption use led lawmakers in the US and abroad to lash out at technology companies that enable such secret communications. Some tech firms also took steps to make it more difficult for terrorist groups to use their tools for communication.

The smartphone app is a sign that IS is developing more capacity to spread information through its own channels. The group's social media accounts and video messages are regularly shut down on platforms such as Twitter and YouTube.

"Increasingly what you will see is the focus on developing means to control the distribution of their materials on a global scale," says Smith.

For the most part, however, IS has relied on many of the most popular social media tools that are easily available to anyone and often protected with little or no security at all. "They're using the same platforms that any Millennial would use," says Farah Pandith, a fellow at the Harvard Kennedy School and the State Department’s former Special Representative for Muslim communities.

In fact, an IS technology guide authenticated by intelligence experts last month ranks the security of more than 30 chat apps that could be in use by the group.

But while IS may use many popular apps to communicate or spread its message, it's unlikely that the group uses a single platform or communications technique when it comes to planning attacks, says Fred Cate, a cybersecurity expert and professor at Indiana University.

"One of the keys, if you were thinking like a terrorist, is to separate your communications for outreach purposes in the most significant ways possible from your communications for operational purposes," Mr. Cate says. “Ideally [you’re] not even using the same devices, the same servers, the same platforms, the same anything."

What's more, it's possible the militants are avoiding using any kind of technology when it comes to planning attacks such as the one in Paris, says Rita Katz, director of the Search for International Terrorist Entities Intelligence Group, a private intelligence firm in Washington.

"Nowadays when [terrorists] need to plan an attack like [Paris], I doubt that they would use Telegram," Ms. Katz says. “Apps are not needed because you are working with people in the same physical location. That gives you a huge advantage because communications are not being intercepted.”

Even though IS may be developing its own communications technology, the group gains a significant advantage by utilizing the scale and ease of use that comes with consumer apps and social media sites, say experts.

"It’s actually to their advantage to use commercial technology," says Ben FitzGerald, a senior fellow at the Center for a New American Security, a Washington think tank. "You can’t shut down something like WhatsApp."

IS will probably mix up its communication methods – encrypted or not – as intelligence agencies uncover channels the group uses, says Mr. FitzGerald. "They’re going to hide their operational communications," he said. "So it’s better to try and push that into places that are easiest to monitor."

Over the past few years, IS has used the public Web to its advantage and experts doubt the militants will back away from that communications strategy.

"IS has released more than 20 videos where someone is driving a car, and another man is shooting from a window and killing people. I mean, that's "Grand Theft Auto,' " says Javier Lesaca, a visiting researcher at George Washington University’s School of Media and Public Affairs. "They know that audiences, when they see that video, it’s going to be familiar to them."

Mr. Lesaca has analyzed more than 1,000 IS audio, visual, and social media campaigns that have been produced by affiliate media groups and produced in studios across the Middle East, Africa, and Russian. He doubts that IS will be backing away from the strategy of producing and publicizing slick marketing videos anytime soon.

"Thirty-eight percent of IS's media shows how they win battles in the field," Lesaca says. "So some of those videos, I don't know if they're real battles or if they're being defeated in those battles, but the reaction in public opinion is that they're always winning."