A Hidden Security Threat: Beware the Office Multifunction Printer

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Cybercriminals are always looking for easy ways to break into your network, whether at work or at home. In a talk at this summer's DefCon 19 conference, security researcher Deral Heiland demonstrated various ways to compromise Internet-ready consumer-grade multifunction printers. These include printers that can scan to a file, scan to email, and fax documents, and the vulnerabilities he found are similar across all vendors.

If you haven't taken the time to access the administration control panel webpage for your printer and change its default passwords, do so now. Unfortunately, that will only slow down a very persistent criminal.

For example, Heiland demonstrated that if you did change the default Toshiba printer password from 123456 to something unique, a criminal can simply add an extra backslash to the URL to gain administrator access to the device. And he said that if you copy the URL from the HP Officejet printer login page and then add "page=" to the end when you paste it back in, this will bypass any new passwords that have been added to those printers. This could let a hacker access sensitive documents that have been recently scanned or printed.

On some of the printer administration webpages, basic coding flaws can also expose sensitive information such as passwords. With the HP Officejet multifunction page, Heiland said he was able to right-click the page in Firefox in order to see the plaintext of the password normally hidden by black dots. The same, he said, was true on the Toshiba models he'd tested.

For office printers, internal address books are often used to route faxes and scanned documents to the individual workstations. Heiland found that, in order to access its address book, Canon requires an attacker to first have a cookie--which, if they are using a Google search to find the administration webpage over the Internet, they would not necessarily have. But if you click to the Home page tab, Heiland said your computer will receive a cookie that allows you to retrieve the plaintext address book from the printer.

Heiland added that Canon did fix this vulnerability on most of its ImageRunner line, but he found two models--IR3580 and IR4080--that still allowed for this particular hack to work.

Another attack takes advantage of the backup feature (or "cloning", as Xerox calls it) on the printer. In the case of Lexmark and Xerox printers, he said the backups exported the account passwords in plain text.

In yet another attack. he was able to redirect the test pages that most printers spit out by intercepting the Lightweight Directory Access Protocol (LDAP) in a sort of man-in-the-middle attack. Here he attacked Sharp and Ricoh printers, redirecting their test pages to him, and setting him up as a valid user.

At the end of his talk, Heiland announced the release of a new penetration testing tool called PRAEDA, which he said is Latin for "to plunder, spoils of war, booty." The tool, in the right hands, can help IT administrators discover multifunction printer vulnerabilities on their network, with modules for each of the vendors cited above. The release of the tool will also undoubtedly put pressure on the printer manufacturers to patch or fix these multifunction printer problems entirely.

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