ISIS checkpoint north of Mosul (file)
ISIS checkpoint north of Mosul (file) Reuters

Islamic State (ISIS) terrorists have showed incredible bravado, boasting to the Western world that they would "overcome" an international coalition and military campaign hours after airstrikes pummeled their Syrian stronghold.

But even ISIS became unnerved over the weekend, after multiple security breaches were shown to have revealed sensitive intelligence on the group to the international community. 

Concerns over cyber-security are so high that ISIS released an Arabic-language publication to combat information theft.

“A number of security gaps have appeared that have benefited the enemy and have helped expose the identities of some brothers or identify some sites used by the  [jihadists - ed.] with ease,” it begins, according to a copy translated by the Financial Times.

The brochure then explains, in detail, how information could be leaked, and expose “data that could turn your hair gray." 

“We know this issue is not only tied to pictures, but to PDF files, word files and video files,” it adds.

The brochure focuses primarily on metadata, tiny nuggets of information hidden in digital files. 

“[It] can contain information about the identity of the author, when the content was created/modified, and potentially reveal location information around where the content was authored,” Darien Kindlund, director of threat research at FireEye, a US cyber security company, told the daily. 

It is also the prime method of information for US and British intelligence sources, as "NSA leaker" Edward Snowden revealed last year. The NSA is known to store the metadata for millions of web users, and the data has become the center of controversy over spying and internet privacy. 

To avoid this, ISIS has even launched an independent campaign for "metadata-scrubbing": Himlat Takteem Ialami, loosely translated as the "media restraint campaign." 

The campaign urges ISIS members - who are notorious for their social media presence - to refrain from revealing their names or locations, or from using uncensored photos of individuals in the group. 

'Crucifictions' amid physical crackdown

ISIS's religious police, or Hisbah, have also been instituting a physical crackdown on data leakage in ISIS's de facto headquarters in Raqqa, sources said.

According to the UK-based Syrian Observatory of Human Rights, 20 people are estimated to have been executed on espionage charges alone in the past three months. 

British intelligence officials told the Times that while the measures seem extreme, they are actually quite typical of radical Islamist movements - and are a sign that airstrikes are becoming more effective. 

“It mirrors what happened with Al Qaeda,” the official said. “As strikes against them became more effective, they became more and more paranoid. They were worried everyone was a spy.”

Other Islamist groups have also reacted in similarly brutal fashion to suspected intelligence leaks. In during Israel's summer war with Gazan terrorists the territory's Hamas rulers summarily executed dozens of suspected "informants" in public, prompting an international outcry - and comparisons to ISIS.

In the latest incident, ISIS crucified a 17 year-old boy for taking photos of an ISIS military base. 

Photos of the body, which have gone viral, feature a handwritten sign around the victim's neck accusing him of "apostasy," according to the Daily Mail - and claim the boy had been caught receiving 500 Turkish lira ($222) for every photograph he took of an Islamic State military base.