Israel’s spy agency, known as the Mossad, has been decoding secret messages sent by the Islamic State (ISIS) and al-Qaeda via eBay and pornographic files, according to the latest edition of a book about the agency.

Gideon’s Spies: The Secret History of the Mossad was first released in 1999, but a new edition out this year includes two additional chapters on Israel during the Arab Spring, reports The New York Post, which carried an excerpt from the book Sunday.

In the excerpt, author Gordon Thomas discusses the importance of cyberwarfare to the Mossad. He claims Israel was responsible for the Stuxnet computer virus which wreaked havoc on Iran’s nuclear program in 2010. He explains how the Mossad’s most skilled cryptographers discovered that al Qaeda was using a technique called steganography to encrypt messages within digital files, hiding them in items offered for sale on eBay.

Meanwhile, Thomas writes, other agents were scouring the online message board Reddit, turning up terrorists using number codes to communicate. On several occasions, the agents discovered plans for terror attacks upon decoding the messages.

Another unnamed source quoted in the book spoke of “X-rated pornographic pictures which conceal documents and orders for the next target,” used by both al-Qaeda and ISIS.

The Mossad agents search for these hidden messages in areas of the internet that cannot be accessed by typical search engines, such as Google. This inaccessible region is called the Dark Side, and consists of billions of web pages.

According to Thomas, when the Mossad discovers a threat to another nation, it provides that information to the nation in question.

The book also talks about an unlikely alliance between the Mossad and Saudi Arabia, in the face of a common threat: a potentially nuclear Iran.

“By November, a mutual cooperation had been agreed that Israel could use Saudi airspace to launch air attacks on Iran’s nuclear facilities and for Israeli drones, rescue helicopters and tanker planes to be positioned over Saudi Arabia and the Red Sea and have refuel facilities at various Saudi airfields.

“The arrangements would come into operation in the event of the Geneva talks failing to satisfy both sides,” Thomas writes.