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CERT Coordination Center

NotifyLink server provides inadequate protection for cryptographic key material

Vulnerability Note VU#581068

Original Release Date: 2005-03-17 | Last Revised: 2005-04-28

Overview

The NotifyLink key exchange protocol contains a vulnerability that significantly reduces the strength of cryptographic keys used to encrypt mail messages.

Description

Notify Technology NotifyLink Enterprise Server allows users to synchronize e-mail between a PDA and a mail server. The application consists of a PDA-specific client and the NotifyLink server, which acts as a proxy between the client and the mail server(s) the user wants to check. For each e-mail account to be monitored, the user provides mail server credentials that are stored on the NotifyLink server and used to periodically check for mail. When new mail arrives, the NotifyLink server stores a reference to the message ID. Depending on the configuration, the message is either sent to the device via SMS ("Push" mode), or the device periodically checks a link on the NotifyLink web server to retrieve the message ("Poll" mode). The product supports multiple PDA platforms and multiple e-mail servers, including IMAP, POP, Microsoft Exchange, and Novell GroupWise.

NotifyLink uses AES keys to encrypt the mail messages that are exchanged between the PDA and NotifyLink server. These keys are stored on the server in a table named ClientDevices, which is protected from unauthenticated access. If the key is not transferred to the PDA manually, the client can retrieve it from the server using an unauthenticated HTTP post to /hwp/get.asp. When keys are transmitted using this method, the server uses a fixed byte reordering scheme to obfuscate the key. This scheme significantly reduces the strength of the key material, providing protection against only the most casual observer. In addition, any attacker in possession of the source code for get.asp will be able to determine the fixed scheme, making the reversal operation trivial.

Impact

This vulnerability significantly reduces the strength of cryptographic keys used to encrypt mail messages.

Solution

Use Manual Key Generation

Configure NotifyLink to use "Manual Key Generation." When NotifyLink is configured this way, the obfuscated key will not be available to an attacker via /hwp/get.asp.

Vendor Information

581068
 
Affected   Unknown   Unaffected

Notify Technology

Notified:  March 29, 2004 Updated:  May 03, 2004

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

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.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Acknowledgements

We thank the NOAA NCIRT Lab for their discovery and analysis of this vulnerability.

This document was written by Jeffrey P Lanza and Will Dormann. It is based on analysis provided by the NOAA NCIRT Lab.

Other Information

CVE IDs: CVE-2005-0809
Date Public: 2005-03-17
Date First Published: 2005-03-17
Date Last Updated: 2005-04-28 15:13 UTC
Document Revision: 32

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