Title: ShoreWare Director Denial of Service and Arbitrary File Modification
Product: ShoreTel ShoreWare Director
Vendor: ShoreTel, http://www.shoretel.com
Vulnerable Versions: 18.61.7500.0, and likely all prior versions.
Tested Version: 18.61.7500.0
Credit: Dennis Kelly <dennis.kelly@gmail.com>

Introduction

ShoreTel ShoreWare Director is the core management interface for
managing ShoreTel's Unified Communication (UC) system.  The ShoreWare
server install includes an IIS FTP service used to distribute
configuration and firmware to IP phones using anonymous FTP.
Additionally, a virtual directory /ShorewareDirector that is not
visible in a directory listing is used by ShoreWare Director for
uploading and storing Auto-Attendant Menu Prompts (System Greetings).

Impact

By default, the /ShorewareDirector directory is available via
anonymous FTP, unrestricted, and with read-write access.  It is
vulnerable to:

- A Denial of Service (DoS) filling up the disk with arbitrary files.
If the directory resides on the C: drive, it could make the entire
server unavailable.  Otherwise, it could prevent administrators from
changing menu prompts or other system functions utilizing the same
disk.

- Unauthenticated changes and deletion of menu prompts actively being
used by the system.  Deleting an actively used file will cause the
system to use the default greeting.  An attacker could overwrite an
active prompt (can take hours to refresh from the FTP server though)
that would result in a good laugh and high fives, but also could be
used to convince users to take further action or disclose sensitive
information as a step in a more complex attack.

Vendor Response

The vendor reports this is a essential component of their platform and
does not impose significant impact to system integrity.  A change
request to the functionality can be submitted to
suggestions@shoretel.com.

Mitigation

Limit access to the /ShorewareDirector directory to an administrative
host or network using FTP Address and Domain Restrictions in IIS.

Timeline

10/04/2013: Vulnerability discovered.
10/07/2013: Vendor contacted.
10/11/2013: Vendor response.
10/13/2013: Disclosure.