Corporate Espionage's New Friend: Embedded Web Servers

Strategic Security Survey: Global Threat, LocalPain

Numerous models of printers, photocopiers, and voice over IP (VoIP) systems are Internet-connected. But their embedded Web servers often use well-known default passwords or firmware that has known vulnerabilities, either of which could be used by remote eavesdroppers to intercept internal communications.

That warning was issued by Michael Sutton, VP of security research for Web security firm Zscaler Labs, last month at the Black Hat security conference, in a session titled "Corporate Espionage for Dummies: The Hidden Threat of Embedded Web Servers." Sutton presented the results of his research, based on using multiple search engines to fingerprint more than one million Web servers, as well as identifying--as much as possible--which of those servers are embedded. Interestingly, Google search appears to suppress results for embedded Web servers. But other search engines, such as Shodan, do not.

Of the one million Web servers fingerprinted, 34.2% ran Microsoft IIS, and 33.6% ran Apache. Beyond that, there were 2,737 unique server headers on the remaining machines, and "a lot of that is embedded Web servers," said Sutton. Many of those servers also lack any security, such as requiring a password to access stored documents or VoIP calls. As a result, Sutton was able to freely download numerous types of documents, including voting advice from a pro-Tea Party organization, copies of signed checks, and scanned technical reports. "My absolute favorite," he said, "is documentation letting us know that Jim is actually a certified mold inspector."

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While that recovered information isn't necessarily earth-shattering, Sutton said that Web-accessible photocopiers and the like are essentially repositories of any recent documents or communications of interest, and thus could serve as a competitive intelligence treasure trove. Some devices even offer would-be attackers time-saving shortcuts. Certain models of Sharp photocopiers, for example, can be set to upload all scanned or copied documents to an external site via FTP, or email them to an outside email address. Meanwhile, some HP all-in-one printers have a feature called Webscan, which allows anyone with a browser to scan and download whatever is on the scanner bed.

Interestingly, the most-prevalent Web-connected devices Sutton found were security cameras, including babycams. "I found a lot of McDonald's Web cams; I don't know why," he said. Most cameras, however, appeared to have been set up to monitor employees.

Of all the devices fingerprinted, however, "the ones that are most concerning are the Ricoh copiers," said Sutton. In particular, 2% of all of the embedded Web servers he found were Ricoh copiers that use a default password of "admin." While the devices offer SSH encryption, many also ran services such as telnet, which an attacker could easily enable and then use to directly access the machines at a later date. Some of the machines also make recently scanned documents available for immediate download in TIFF or PDF format.

Going forward, Sutton said he's hoping to amass better information--which he'll share freely--for fingerprinting every type of embedded Web server (EWS) he finds, in part to help businesses understand which internal devices may have embedded Web servers with known vulnerabilities. To that end, he's released BREWS (for basic request embedded Web server), which he described as a "crowd-sourcing initiative to build a global database of EWS fingerprinting data."

But what can be done to EWS vulnerabilities now? First, embedded Web servers need to be included in corporate patch management plans, and vendors must push patches. "The hardware industry is at least a decade behind the software industry in terms of security," said Sutton. "We definitely need to move to a system that's more common, like Apple TV, where new patches just get pushed to you." For example, one of the most widely used embedded Web servers is Allegro RomPager, which its manufacturer says runs in 75 million devices. During his research, Sutton found at least 3,000 devices running a version of RomPager that contains a known vulnerability that could be used to crash the server.

Next, devices need to ship with security-compromising features, such as the ability to automatically upload scanned documents to an FTP site, disabled. "I really place the blame on the vendors," said Sutton. "This functionality often serves no useful purpose, and it really doesn't need to be there." When it is useful, however, such functionality should be enabled by default, using a unique password such as the serial number of the device's MAC address.

Until those changes occur, corporate IT managers should regard anything with an embedded Web server as a potential security threat, and secure it appropriately. "In the enterprise ... you need to treat a photocopier or any network-enabled device the same way as a computer," said Sutton.

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