Vendor: Hewlett-Packard, http://www.hp.com
Affected Products: Various HP LaserJet MFP devices
(See HP advisory  for the complete list)
Vulnerability: Directory Traversal in PJL interface
2009/11/25 Initial notification of Hewlett-Packard
2009/11/25 HP confirms receival of advisory
2010/02/05 n.runs AG requests update on the reported issue
2010/02/05 HP notifies n.runs AG that an advisory is in preparation
2010/11/15 Publication of HP advisory
The Printer Job Language (PJL) was developed by Hewlett-Packard to
provide a method for switching printer languages at the job level
and for status exchange between the device and a host computer.
Besides the possibility to view and change parts of the printer's
configuration or modify control panel messages PJL allows some limited
form of file system access. PJL is used "above" other printer languages
such as PCL and is usually accessible on port 9100. Detailed
information about PJL can be found in the PJL Technical Reference
A directory traversal vulnerability has been found in the PJL file
system access interface of various HP LaserJet MFP devices.
File system access through PJL is usually restricted to a specific
part of the file system. Using a pathname such as 0:\..\..\..\ it
is possible to get access to the complete file system of the device.
Proof of Concept:
The following command can be used to reproduce the problem. It lists
all files in the root directoy of the device:
$ python -c 'print "\x1b%-12345X () PJL FSDIRLIST NAME=\"0:\\..\\..\\..\\\" \
ENTRY=1 COUNT=999999\x0d\x0a\x1b%-12345X\x0d\x0a"' | nc 192.168.0.1 9100
@PJL FSDIRLIST NAME="0:\..\..\..\" ENTRY=1
This vulnerability allows sensitive information to be disclosed
and potentially be modified. This includes spooled print jobs,
received faxes, log files or other settings of the device.
See the HP advisory  for possible workarounds.
Bug found by Moritz Jodeit of n.runs AG.
This Advisory and Upcoming Advisories:
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