Re: HP Web JetAdmin vulnerabilities. Apr 27 2004 09:42AM
FX (fx phenoelit de)
Just a few more for HP Web JetAdmin 6.5 - I'm tired of waiting for HP and
since the current version is way past 6.5, there is no point in hiding it
any more :)


Phenoelit Advisory <wir-haben-auch-mal-was-gefunden #0815 ++-+>

[ Title ]
Multiple vulnerabilities in HP Web JetAdmin

[ Authors ]
FX <fx (at) phenoelit (dot) de [email concealed]>

Phenoelit Group (http://www.phenoelit.de)
Advisroy http://www.phenoelit.de/stuff/HP_Web_Jetadmin_advisory.txt

[ Affected Products ]
Hewlett Packard (HP)
Web JetAdmin 6.5 on any platform

Partially affected:
Web JetAdmin 7.0 on any platform
Web JetAdmin <=6.2 on any platform

HP Bug ID: SSRT2397
CERT VU ID: VU#606673

[ Vendor communication ]
10/28/02 Initial Notification, security-alert (at) hp (dot) com [email concealed]
*Note-Initial notification by Phenoelit
includes a CC: to cert (at) cert (dot) org [email concealed] by default

From there on, communication went back and forth, while the major
version went up and only a subset of the bugs was fixed.

[ Overview ]
HP Web JetAdmin is an enterprise management system for large amounts
of HP printers, print servers and their respective print queues. The
service provides a web interface for administration, by default
listening on port 8000. The web server (HP-Web-Server-3.00.1696) is a
modular service supporting plugins and using .hts and .inc files for
creation of active content.

From the readme_en.txt file:
''HP Web JetAdmin contains support for all HP JetDirect-connected
printers and plotters. This product allows users to manage HP
JetDirect-connected printers within their intranet using a
browser. In addition to this, HP Web JetAdmin has the ability
to discover and manage any non-HP printer that implements the
standard printer MIB (RFC 1759). If a peripheral includes an
embedded web server, HP Web JetAdmin provides a link to the
home page of the peripheral.''

NOTE: (Historic, see initial date!)
Despite the fact that the HP web site still advertises it as
6.5, the Web JetAdmin you can currently download is 7.0. This
one features an Apache core and several improvements, including
SSL support with a vulnerable version of OpenSSL (0.9.6c).
Password decryption and direct calls of functions are still
possible, but some of the exploited functions are no longer

[ Description ]
Multiple vulnerabilities exist in the product. A short summary is
outlined below:
1 - Source disclosure of HTS and INC files
2 - Real path disclosure of critical files
3 - Critical files accessible through web server
4 - User and Administrator password disclosure and decryption
5 - User and Administrator password replay
6 - Root/Administrator password disclosure
7 - Denial of Service of the server due to input validation failure
8 - Authentication circumvention on all functions
9 - Direct access to methods of the server core and the plugins via
the HTTP Protocol
10 - Input validation failure for strings written to files
11 - Root/Administrator compromise due to all of the above
12 - Hidden games (easter egg) in the application

[ Vulnerability details ]
[ 1 ]
The web server will disclose the contents of the scripts, if a dot (.)
is added to the end of the request URL.

[ 2 ]
Any page that is generated by the .HTS scripts will include a HTML
comment line with the location of the file framework.ini, which holds
several critical entries.
<!-- framework.ini F:\Program Files\HP Web JetAdmin\doc\plugins\framework\framework.ini -->

[ 3 ]
The file framework.ini is located inside the web root directory. Any
unauthenticated user can access it. This file contains the encrypted
(see below) passwords for all users, permissions for the respective
users and other valuable information.

[ 4 ]
HP Web JetAdmin uses it's own encryption. Passwords will be encrypted
on client side before send to the server using a Java applet. The
encryption is easily broken and reversible.
An encrypted username or password is transmitted and stored in the
ASCII representation of hexadecimal numbers. Such a ciphertext looks
like 6a206d14000a7c2bc3cd3358153cffb5. This string has three elements:
- 6a206d14 is the initialization vector for the algorithm
- 000a is the length of the encrypted data (and double the length of
the clear text)
- 7c2bc3cd3358153cffb5 is the actual encrypted data

Encryption and decryption are performed by initializing a random
number generator with the IV supplied in the string and performing an
XOR operation with the encrypted data and the upper 8 bits of the
subsequently calculated random numbers. The following pseudo-code will
be run:

long v = IV;
for(int i=0;i<strlen(code);i++){
v = 31413L * v + 13849L & -1L;
code[i]=code[i]^(char)(v >> 24);

As the result, the clear text will be in code[] as two-byte

[ 5 ]
Because of the static nature of the encryption broken in point 4, an
attacker can use password strings sniffed off the network and use them
in selfmade HTTP requests to the service. This is commonly referred to
as replay attack.

[ 6 ]
When using services the host system provides only to administrative
users (Administrator on Windows, root on UNIX), the web interface will
require the user to enter the account data for this account. The
entered username, password and (for Windows) the domain name are
encrypted with the algorithm discussed in 4. Therefore, an attacker
can sniff the strings off the network and decrypt the account

[ 7 ]
By modifying the "encrypted" string, an attacker can cause the service
to lock up. As discussed in point 4, the second element in the string
represents the length of the encrypted data. By replacing it with
0xFFFF, the decryption function loops through the string until the
index reaches -1, which never happend during tests and resulted in a
completely frozen service.
Example: 01010101FFFF02020202020202020202.

[ 8 ]
Access to the functionality of Web JetAdmin is usually done via HTTP
POST requests. One of the variables always present is "obj". A typical
request contains:
By leaving out the element "Framework:CheckPassword;", HP Web JetAdmin
will no longer validate the supplied password and immediately grant
access to the function specified.

[ 9 ]
The "obj" variable discussed in 8 is actually used to call functions
in the server core or any plugin. The server core and the plugins
export functions to be used via HTTP. Therefore, an attacker can craft
HTTP POST requests to use internal functions. Additionally, use of
variables and grouping of function calls are possible. One can
actually write little programs and submit them to the server for
execution. Most of the functions deal with internal data structures
and files of HP Web JetAdmin.
Example: see 8

[ 10 ]
HP Web JetAdmin uses a file called "cache.ini" outside of the web
root. This file will contain session settings for a specific session.
The session is identified by a variable called __BrowserID submitted
in every HTTP request of the session. The format of cache.ini is:

where 1234 and 5678 are the browser ID values. An attacker can
influence the Variable=Value pairs through the call interface
described in 9. By calling
the following cache entry is created:

It is also possible to inject multiple lines at the beginning of the
file by including HTTP encoded linefeed characters in the __BrowserID
will create the following entry:
Test 123

[ 11 ]
The Httpd core supports an exported function called "ExecuteFile".
This function takes two or more parameters. The first one is the path
where the file is located (leave blank for use of $PATH or %PATH%) and
the second is the executable itself. Combined with the ability to
write arbitrary content to a file in a known location (see 10,
location known due to 2), an attacker can easily start a program of
his choice. Since the service usually runs as root on UNIX or as
SYSTEM on Windows, this gives full remote access to the server.
Example: see Example section below

[ 12 ]
The security issues described above are not the result of a lack of
time in the development department. This is proven by the fact that
HP Web Jetadmin is delivered including two games.
A text based adventure game is available on the URI:
The HTS file special2.hts features a hangman game and a list of
Hint: When playing the text adventure, throw the cat toy around to
keep the bad kitty busy.

[ Example ]

The root/SYSTEM exploit for 6.5 (NOT 7.0) can be found at:

[ Solution ]
None known at this time. HP Web JetAdmin 7.0 fixes some of the
problems - namely removed the ExecuteFile function - but most of the
issues and the games are still there.

[ end of file ]

FX <fx (at) phenoelit (dot) de [email concealed]>
Phenoelit (http://www.phenoelit.de)
672D 64B2 DE42 FCF7 8A5E E43B C0C1 A242 6D63 B564

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