Donato Ferrante


Application:  Open Dc Hub
              http://opendchub.sourceforge.net/

Version:      0.7.14

Bug:          Buffer Overflow

Date:         24-Nov-2004

Author:       Donato Ferrante
              e-mail: fdonato@autistici.org
              web:    www.autistici.org/fdonato



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1. Description
2. The bug
3. The code
4. The fix



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1. Description:
----------------

Vendor's Description:

"An Open Source Linux/Unix version of the hub software for Direct
Connect."



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2. The bug:
------------

The program doesn't correctly manage the $RedirectAll command.
In fact it will have a buffer overflow, letting an attacker to execute
arbitrary code on the victim system.

NOTE: To exploit the bug the attacker needs to have admin privilege on
the victim hub.



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3. The code:
-------------

To test the vulnerability:

http://www.autistici.org/fdonato/poc/OpenDcHub[0714]BOF-poc.zip



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4. The fix:
------------

No fix.
The vendor has not not replied to my mails.

In the meantime give admin access only to trusted people.
If you want you can use my following little patch that should fix this
bug:


/* patch */


--- commands.c  2004-11-21 13:01:48.000000000 +0100
+++ patch.c     2004-11-21 13:05:33.000000000 +0100
@@ -2842,7 +2842,7 @@
 {
    char move_string[MAX_HOST_LEN+20];

-   sprintf(move_string, "$ForceMove %s", buf);
+   snprintf(move_string, MAX_HOST_LEN, "$ForceMove %s", buf);

    send_to_humans(move_string, REGULAR | REGISTERED | OP, user);
    remove_all(UNKEYED | NON_LOGGED | REGULAR | REGISTERED | OP, 1, 1);


/* end patch */



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