ISIS may possibly be able to print Syrian passports at will since capturing the cities of Deir ez-Zour and Raqqa, each of which hosted a passport printing office of the Syrian government, in the summer of 2014. The terrorist organization is suspected to have stolen the printing machines and boxes of blank passport booklets for its own use, according to a Homeland Security Investigations (HSI) Intelligence Report.
While FBI Director James Comey and other security experts have warned about the danger of ISIS using the machine to fraudulently send terrorists to the United States, the report also notes that fake documents were already ubiquitous in Syria: "[F]ake Syrian passports are so prevalent in Syria that Syrians do not even view possessing them as illegal. The source stated fake Syrian passports can be obtained in Syria for $200 to $400 and that backdated passport stamps to be placed in the passport cost the same."
Deir ez-Zour is considered a contested city, meaning ISIS's control there is not absolute and the machine may not be captured. Raqqa, however, functions as the capital of ISIS territory, and thus it is more likely that the passport office there has been taken.