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CERT Coordination Center


Retrospect Backup Client uses weak password hashing

Vulnerability Note VU#101500

Original Release Date: 2015-06-15 | Last Revised: 2015-06-15

Overview

Retrospect Backup Client is a client to a network-based backup utility. This client stores passwords in a hashed format that is weak and susceptible to collision, allowing an attacker to generate a password hash collision and gain access to the target's backup files.

Description

CWE-916: Use of Password Hash With Insufficient Computational Effort - CVE-2015-2864

Retrospect Backup clients prior to 10.0.2 on Windows and Linux and 12.0.2 on Mac contain an error in the password hash generating algorithm. The password is not fully utilized when generating a hash, allowing the possibility of a weak hash with a higher probability of collision with other passwords. Attackers with network access to a machine running the Retrospect client may be able to generate brute-force passwords that are guaranteed to collide with the hashed password with a maximum of 128 tries. This attack was demonstrated by security researchers Josep Pi Rodriguez and Pedro Guillen Nunez.

This vulnerability only affects clients utilizing password authentication; clients using the public key authentication mechanism to login are unaffected. Retrospect recommends that users make use of the public key authentication mechanism. For more details on the vulnerability and instructions on enabling public key authentication, please see Retrospect's advisory.

Impact

An unauthenticated attacker on the network may be able to brute force a correct password by guessing a string that produces the same hash, granting access to backup data as the victim user.

Solution

Apply an update

For users that wish to continue using the password mechanism, Retrospect has released updates addressing this issue.

Windows users should update to version 10.0.2.119 or later.
Mac users should update to version 12.0.2.116 or later.
Linux users should update to version 10.0.2.104 or later.

Affected users may also consider the following workaround recommended by the vendor:

Switch to Public Key Authentication

The public key authentication method used by Retrospect is unaffected by this vulnerability. Retrospect recommends using public key authentication rather than a password and has provided a knowledge base article to guide users through the setup process.

Vendor Information

101500
Expand all

Retrospect, Inc.

Notified:  April 30, 2015 Updated:  June 15, 2015

Statement Date:   June 11, 2015

Status

  Affected

Vendor Statement

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

Vendor Information

Retrospect has released updates addressing these issues.

Windows users should update to version 10.0.2.119 or later.
Mac users should update to version 12.0.2.116 or later.
Linux users should update to version 10.0.2.104 or later.

The public key authentication method used by Retrospect is unaffected by this vulnerability. Retrospect recommends using public key authentication rather than a password and has provided a knowledge base article to guide users through the setup process.

Vendor References

http://www.retrospect.com/support/kb/cve_2015_2864

Addendum

There are 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 7.9 AV:A/AC:M/Au:N/C:C/I:C/A:C
Temporal 6.2 E:POC/RL:OF/RC:C
Environmental 4.6 CDP:ND/TD:M/CR:ND/IR:ND/AR:ND

References

Credit

Thanks to Josep Pi Rodriguez and Pedro Guillen Nunez for working with the CERT/CC and the vendor, and thanks to Retrospect for quickly addressing the issue.

This document was written by Garret Wassermann.

Other Information

CVE IDs: CVE-2015-2864
Date Public: 2014-07-09
Date First Published: 2015-06-15
Date Last Updated: 2015-06-15 21:42 UTC
Document Revision: 28

Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.