They also gave out specific advice, recommending jihadists use privacy-protecting email systems like TOR, also called The Onion Router, to hide their computer's IP address, and to use encrypted links to access jihadi forums, Raisman said. While TOR originally was designed to help dissidents communicate in countries where the Internet is censored, it is facing legal difficulties because criminals allegedly have used it as well.
"Criminals are doing well without things like TOR," said Karen Reilly, a spokeswoman for TOR. "If TOR disappeared tomorrow they would still have secure, anonymous access to the Internet. ... Their victims would not."
Other analysts predicted a two-track evolution away from the now-exposed methods of communication: A terrorist who was using Skype to plan an attack might stop using that immediately so as not to expose the imminent operation, said Ben Venzke of the private analysis firm IntelCenter.
But if the jihadi group uses a now-exposed system like YouTube to disseminate information and recruit more followers, they'll make a gradual switch to something else that wasn't revealed by Snowden's leaks - moving slowly in part because they'll be trying to determine whether new systems they are considering aren't also compromised, and they'll have to reach their followers and signal the change. That will take time.
"Overall, for terrorist organizations and other hostile actors, leaks of this nature serve as a wake-up call to look more closely at how they're operating and improve their security," Venzke said. "If the CIA or the FBI was to learn tomorrow that its communications are being monitored, do you think it would be business as usual or do you think they would implement a series of changes over time?"
The disclosure that intelligence agencies were listening to Osama bin Laden drove him to drop the use of all electronic communications.
"When it leaked that bin Laden was using a Thuraya cellphone, he switched to couriers," said Jane Harman, former member of the House Intelligence Committee and now director of the Woodrow Wilson International Center. "The more they know, the clearer the road map is for them."
It took more than a decade to track bin Laden down to his hiding place in Abbottabad, Pakistan, by following one of those couriers.
