China’s Ministry of State Security warns of espionage risks in office printers

China's Ministry of State Security (MSS) on Friday released an article reminding the public that printers, as frequently used devices in modern offices, pose significant security risks that must not be overlooked. It has been discovered that some foreign intelligence agencies specifically purchased second-hand printers to extract residual classified documents, forming a hardware-based data theft supply chain.

The article said that some printer software on certain download platforms has been found to contain remote-access trojans, which spread to large numbers of user devices through download links and enable remote control for data theft. This type of supply chain attack compromises companies' software development environments by embedding malicious code into official software, creating a "download-and-get-hit" precision attack model.

The high-voltage electrostatic fields of laser printers and the piezoelectric ceramic vibrations of inkjet printers generate electromagnetic signals that can also be intercepted. These signals can penetrate standard building walls and glass. With specific algorithms, the printed content can be accurately reconstructed, posing a significant leakage risk, according to the MSS.

Such "invisible leakage channels" can be exploited by foreign intelligence agencies to steal printed information, read the article.

The article also noted that most printers have built-in storage modules that automatically cache printing tasks, including output documents and scanned images. If a printer used for classified files is retired without properly disposing of its storage chip, the underlying data can still be recovered through technical means - even after record deletion or a factory reset - posing a security risk.

It has been discovered that some foreign intelligence agencies specifically purchase second-hand printers to extract residual classified documents, forming a hardware-based data theft supply chain, according to the MSS.

The ministry listed ways to prevent data leakage. It urged users to always download the latest printer drivers from official websites and avoid third-party high-speed download links. Before installation, hash values should be verified using antivirus software. Printers handling classified documents must remain offline, with non-essential features like remote control, printer sharing, USB, and Bluetooth disabled.

Low-emission devices certified by official authorities should be prioritized. Classified-use printers should be placed centrally, away from walls and windows, to minimize the risk of electromagnetic data interception.

Printers should have removable storage chips. When decommissioning such equipment, deep data wiping should be performed using official tools. Designated personnel should remove and degauss storage chips, and certified institutions should handle final disposal, according to the ministry article.

(Global Times)