BSCW vulnerable to arbitrary file overwriting via symlink redirection of temporary file

Overview

BSCW is a groupware system that runs on a web server. BSCW follows symbolic links in tar files that it extracts into a user’s local area. Accessing those links may allow the user to view arbitrary files viewable by the web server, and to overwrite files writable by the web server.

Description

BSCW provides for a number of upload and download options, plus on-line access to documents via a “data bag” (a local area for each user). One of the features supported by BSCW is extraction of uploaded tar files into the “data bag.” Reportedly, when a tar file containing symbolic links is extracted into the “data bag”, BSCW will support access to the linked object under the web server’s userid.

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Impact

By creating symbolic links to files on the web server and placing them in a tar file, then extracting them into the “data bag,” an attacker reportedly could view any file readable by the web server. By modifying these files via BSCW, the attacker may be able to overwrite files writable by the web server. Directly uploading symbolic

links will not work as the BSCW software either refuses this upload with an error message or hangs on the upload.

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Solution

Apply vendor patches; see the Systems Affected section below.

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Vendor Information

465971

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BSCW.gmd __ Affected

Notified: July 16, 2001 Updated: October 01, 2001

Status

Affected

Vendor Statement

<http://bscw.gmd.de/Bulletins/BSCW-SB-2001-08.extract.txt&gt;

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23465971 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://bscw.gmd.de/pyc20&gt;
• <http://bscw.gmd.de/&gt;
• <http://bscw.gmd.de/Bulletins/BSCW-SB-2001-08.extract.txt&gt;
• <http://www.orbiteam.de>
• <http://www.securityfocus.com/bid/3227&gt;

Acknowledgements

This vulnerability was first described on the Bugtraq mailing list.

This document was last modified by Tim Shimeall.

Other Information

CVE IDs:	CVE-2001-0973
Severity Metric:	4.73 Date Public: