[NT] BearShare Directory Traversal Issue Resurfaces

From: support@securiteam.com
Date: 10/03/02 

From: support@securiteam.com
To: list@securiteam.com
Date: Thu,  3 Oct 2002 21:03:13 +0200 (CEST)

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  BearShare Directory Traversal Issue Resurfaces
------------------------------------------------------------------------

SUMMARY

A while back BearShare 2.2.2 was
<http://www.securiteam.com/windowsntfocus/5SP0P2K40U.html> reported to
have a directory traversal vulnerability in it. This issue was fixed by
the company, now a different variant of the same issue seems to have
resurfaced, allowing a remote attacker to view any file he desires by
issuing a specially crafted HTTP request.

Despite a correction attempt in part of the vendor, the updated version is
still vulnerable.

DETAILS

Vulnerable systems:
 * BearShare version 4.0.5
 * BearShare version 4.0.6 (second variant)

Vendor response:
"The fix for the directory traversal issue you reported to us has been
released as part of BearShare 4.0.6. All users will be notified by the
application itself that a new version is available."

Workaround:
Users that do not upgrade are recommend to deactivate the built in
personal web server by choosing Setup->Uploads and un-checking the
"Activate the built in personal web server" check box.

Example (first variant):
Issuing the following request:

http://127.0.0.1:6346/%5c..%5c..%5c..%5cwindows%5cwin.ini

Would translate into:
http://127.0.0.1:6346/\..\..\..\windows\win.ini

Returning the win.ini file.

Second variant:
Following the release of BearShare version 4.0.6, Gluck has informed us
that this version is still vulnerable to a simple variant of the attack
which indicates bearshare has not done a good job of fixing the problem.
This time issuing the following request would work:

http://127.0.0.1:6346/%5c..%5c..%5c..%5cwindows%5cwin%2eini

ADDITIONAL INFORMATION

The information has been provided by <mailto:gluck@securedream.net> Gluck
and <mailto:mario@freepeers.com> Mario Solares.

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