Lexmark C4342 Security White Paper - Page 39

updating firmware through flash files, Support is limited to printing image files

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Secure Access 39 Lexmark devices support only devices that enumerate with a mass storage device class and HID for simple input devices (for example, keyboards and authentication card readers) and specific chip card interface device (CCID) card reader devices used for authentication. This means that if a device, such as a USB network card, is inserted, the printer does not establish a connection to it. USB flash drives are a typical example of the sort of device you might expect to use with Lexmark devices. These devices are widespread today and are generally supported by printers and MFPs. Devices that are SCSI‑compliant use the FAT32 file system and do not include an embedded hub, so they are likely to be recognized and compatible with Lexmark devices. If a USB device does not meet these requirements, then the printer or MFP rejects the external device. One other supported device is the Lexmark wireless adapter. This device is uniquely recognized by the enumeration process and accepted by a Lexmark printing device. Support is limited to printing image files, direct flash drive scanning, and updating firmware through flash files When a USB flash drive is inserted in a device's USB host port, the printer or MFP examines the file system of the inserted device and displays a list of the image files (BMP, DCX, GIF, JPEG, JPG, PCX, PDF, PNG, TIF, and TIFF) and firmware files (FLS) on the device. No other type of file is displayed or supported. Files that contain PostScript emulation or PCL emulation data streams are not supported. When you decide to print a file, the contents of the file are read from the USB-attached device and transferred to the appropriate image interpreter. This component of the device's firmware inspects the format of the file and discards files that are not of that file's format. Also, firmware files are accepted on the device only if signed by Lexmark, ensuring that tampered firmware can never be installed on your device. This eliminates any opportunity to submit a file by mislabeling it. In other words, a person cannot load executable code in the printer by storing it in a file called, for example, HarmlessJob.pdf. Image files are treated internally, just as if they were submitted to the device through any of the other device ports (parallel, network, and so on). This means that the USB host port does not provide any avenues for submitting data that did not already exist. In many regards, the USB host port is less forgiving because the printer decides whether to display and allow the submission of data through the USB connection. Unlike other connections, the printer determines what can be sent to it through the USB port. There is no support for submitting executable code, code updates, configuration changes or anything other than BMP, DCX, GIF, JPEG, JPG, PCX, PDF, PNG, TIF, and TIFF files to the printer through the USB port. Another method for printing image files that are supported for some devices is printing from digital cameras that support the PictBridge connection. There is no way to import files using this connection. The only result that can be obtained is printing of image files that are resident in the camera or in the device for those devices that support PictBridge. If the device does not support PictBridge or the camera is not supported, an error message is displayed. No support for startup from USB-attached devices On many personal computer systems, the USB host port is included in the list of partitions that can be used for startup; that is, you can potentially start such computers from a flash drive. However, this is not permitted with Lexmark devices. The USB ports are not included in the startup sequence.

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Lexmark devices support only devices that enumerate with a mass storage device class and HID for simple
input devices (for example, keyboards and authentication card readers) and specific chip card interface device
(CCID) card reader devices used for authentication. This means that if a device, such as a USB network card,
is inserted, the printer does not establish a connection to it. USB flash drives are a typical example of the sort
of device you might expect to use with Lexmark devices. These devices are widespread today and are generally
supported by printers and MFPs.
Devices that are SCSI
‑
compliant use the FAT32 file system and do not include an embedded hub, so they are
likely to be recognized and compatible with Lexmark devices. If a USB device does not meet these
requirements, then the printer or MFP rejects the external device. One other supported device is the Lexmark
wireless adapter. This device is uniquely recognized by the enumeration process and accepted by a Lexmark
printing device.
Support is limited to printing image files, direct flash drive scanning, and
updating firmware through flash files
When a USB flash drive is inserted in a device’s USB host port, the printer or MFP examines the file system of
the inserted device and displays a list of the image files (BMP, DCX, GIF, JPEG, JPG, PCX, PDF, PNG, TIF, and
TIFF) and firmware files (FLS) on the device. No other type of file is displayed or supported. Files that contain
PostScript emulation or PCL emulation data streams are not supported. When you decide to print a file, the
contents of the file are read from the USB-attached device and transferred to the appropriate image interpreter.
This component of the device’s firmware inspects the format of the file and discards files that are not of that
file’s format. Also, firmware files are accepted on the device only if signed by Lexmark, ensuring that tampered
firmware can never be installed on your device. This eliminates any opportunity to submit a file by mislabeling
it. In other words, a person cannot load executable code in the printer by storing it in a file called, for example,
HarmlessJob.pdf.
Image files are treated internally, just as if they were submitted to the device through any of the other device
ports (parallel, network, and so on). This means that the USB host port does not provide any avenues for
submitting data that did not already exist.
In many regards, the USB host port is less forgiving because the printer decides whether to display and allow
the submission of data through the USB connection. Unlike other connections, the printer determines what can
be sent to it through the USB port.
There is no support for submitting executable code, code updates, configuration changes or anything other
than BMP, DCX, GIF, JPEG, JPG, PCX, PDF, PNG, TIF, and TIFF files to the printer through the USB port.
Another method for printing image files that are supported for some devices is printing from digital cameras
that support the PictBridge connection. There is no way to import files using this connection. The only result
that can be obtained is printing of image files that are resident in the camera or in the device for those devices
that support PictBridge. If the device does not support PictBridge or the camera is not supported, an error
message is displayed.
No support for startup from USB-attached devices
On many personal computer systems, the USB host port is included in the list of partitions that can be used for
startup; that is, you can potentially start such computers from a flash drive. However, this is not permitted with
Lexmark devices. The USB ports are not included in the startup sequence.
Secure Access
39