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Researcher Wants to Kill Hidden Printer Dots on Documents to Help Whistleblowers

It wouldn't be too difficult to fix the problem

Jun 9, 2017 18:45 GMT  ·  By
NSA's whistleblowers would be safer
   NSA's whistleblowers would be safer

One security researcher is on a war path against those hidden dots left behind by laser printers, dots which may be the reason why the DOJ figured out who was behind the latest NSA leak regarding Russia's hacking of the US voting system ahead of last year's elections. 

Gabor Szathmari, who works for CryptoAustralia, says he wants to develop a method to improve security of leaked documents by removing the hidden dots left behind by laser printers. This is a system that's in place to watermark documents and track down leakers, which is exactly what it helped for.

Szathmari has submitted a pull request to the PDF Redact Tools, which is a project for securely redacting and stripping metadata from documents before they are published. His request is that the PDF Redact Tools add a code routine that would allow people to convert documents to black & white before publishing, which would convert colors like the faded yellow dots to white.

Earlier this week, it was revealed that Reality Leigh Winner, a 25-year old NSA contractor, was charged with leaking top-secret NSA documents to The Intercept. The story she chose to leak is about Russian intelligence agents who used a spearphishing campaign to hack into at least one company providing voting machines in the United States.

The yellow dots

Following these two revelations, Errata Security's Rob Graham came up with the theory that the NSA might have figured out who was behind the leak by comparing these barely visible yellow dots left behind by the laser printer to the document. These markings are barely visible, but when arranged on a grid, they can tell the time and date when the document was printed, as well as the printer's serial number.

This has been a long-standing problem and the Electronic Frontier Foundation (EFF) has warned people against companies that use this technique to watermark documents in order to avoid, or to track down, leaks.

While Szathmari's solution does protect whistleblowers from this particular threat, it doesn't remove the risk of them getting caught altogether.