Cybersecurity

Leave No Trace: How Your Printer Could Be Exposing Your Identity

In 2017, NSA contractor Reality Winner went to great lengths to expose classified documents detailing Russian interference in the 2016 presidential election. While Winner’s methods were sound, the journalist who published the piece inadvertently outed her identity by including a scanned copy of the printed documents.

Office Printer

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Unbeknownst to the author, the FBI was able to use the hidden watermarks on the top and sides of the printed pages to discern incriminating metadata, including the serial number of the printer that was used, where it was located, and at what time the document was printed. With that information, the FBI was then able to narrow the list of suspects down to one.

Sentenced to five years and three months in prison, Reality Winner was convicted because of a printer.

Why your printer keeps records

Developed back in the mid-1990s, the practice of printer watermarking (often referred to as printer stenography) was originally implemented to help track counterfeit bills. Once reserved for special printers and scanners, every modern printer today uses some type of watermarking technology. While there’s no way to know which types of printers contain these identifiers, it’s safe to assume that every manufacturer features its own kind of watermarked metadata.

These tiny dots, usually on the sides or corners of a printed page, feature unique identifiers that include the make, model, and even the specific serial number of the printer that was used. More than that, they contain potentially invasive clues that can link any piece of paper to the person who printed it. This means that every page you’ve ever printed could hypothetically be traced back to you.

For shared printers, the risk is much greater. Because these information logs actually indicate which computer connected to the printer at what time, it’s incredibly easy to pinpoint exactly where a document came from—taking any question of anonymity out of the picture.

Ways to stop your printer from tracking you

Experts suggest the best ways to prevent your printer from using tracking dots are to either print with black ink only  or to use a printer that doesn’t produce these types of dots. The former is considered a half-hearted fix, as other identifiers may still be present; the latter is impractical  because  there is no real way to tell which printers don’t produce watermarks. In fact, the Electronic Frontier Foundation started compiling a list of known printers that contain watermarks but stopped updating it after concluding  that every modern printer uses at least some type of unique identifier.

If you’re using a shared printer and are concerned about the documents you’re printing, make sure you delete the printer’s activity logs after every session. And if the printer network offers its own password system, make sure that is enabled as well.

While a proactive approach may help cut back on the amount of potential metadata a printer stores, the unfortunate truth is that there may not be a valid way to prevent your printer from tracking you. Therefore, it’s best to err on the side of caution in order to minimize your risk of exposure.

Tips to keep in mind when getting rid of an old printer

Printers come and go, but the metadata contained within them can last a lifetime. Before you trash or sell your old printer, make sure you wipe whatever information it might have stored inside.

Printers that are able to save your settings, store data, offer private printing options, or include a print queue typically save and store metadata. Fortunately, deleting this information is usually much easier than it sounds. As most printers don’t have  a lot of memory, you may be able to  quickly and efficiently wipe your printer’s cache by first turning your printer on, then unplugging the printer, and then plugging it back in. Check to make sure any saved data is now erased. If so, your printer’s memory has been wiped.

For wireless printers, it’s recommended you go the extra step and go through the manufacturer’s settings to manually reset your printer so that any and all traces of past Wi-Fi connections and devices used is wiped clean.

It’s important to note that while these steps may help clear your printer’s memory, the tiny identifiers that show up in the printed documents are impossible to erase. When it comes to scanning or printing out confidential information, nothing beats the old-fashioned pen-and-paper approach.

alt link text Jack Warner is an accomplished cybersecurity expert with years of experience under his belt at TechWarn, a trusted digital agency to world-class cybersecurity companies. A passionate digital safety advocate himself, Jack frequently contributes to tech blogs and digital media sharing expert insights on topics such as whistleblowing and cybersecurity tools.