According to Rob Graham, who writes for the blog Errata Security, the Intercept’s scanned images of the intelligence report contained tracking dots – small, barely visible yellow dots that show “exactly when and where documents, any document, is printed.” Nearly all modern color printers feature such tracking markers, which are used to identify a printer’s serial number and the date and time a page was printed. “Because the NSA logs all printing jobs on its printers, it can use this to match up precisely who printed the document,” Graham wrote. more
Long term readers of the Security Scrapbook already knew about this.
From 10 years ago... Is Your Printer Spying on You? Good!
