Security Issue Alert

Cisco IOS and Cisco IOS XE Type 4 Passwords Issue

 
Threat Type:CWE: Design Error
IntelliShield ID:28621
Version:1
First Published:2013 March 18 16:04 GMT
Last Published:2013 March 18 16:04 GMT
Port: Not available
Urgency:Possible use
Credibility:Confirmed
Severity:Mild Damage
 
Version Summary:Cisco IOS and Cisco IOS XE devices contain an issue that could allow an authenticated, remote attacker to access sensitive information on a targeted device. Updates are not available.
 
 
Description
Cisco IOS and Cisco IOS XE devices contain an issue that could allow an authenticated, remote attacker to access sensitive information on a targeted device.

The issue is due to an implementation flaw in the affected software. The affected software implements an algorithm to hash user-provided plaintext passwords. This algorithm is called Type 4, and a password hashed using this algorithm is referred to as a Type 4 password. The algorithm design called for using Password-Based Key Derivation Function version 2 (PBKDF2), as described in RFC 2898 section 5.1, with the following input values:
  • Hash algorithm = SHA-256
  • Password = the user-provided plaintext password
  • Salt = 80 bits (generated by calling a cryptographically secure random number generator)
  • Iteration count = 1,000 (one thousand)
Due to an implementation issue, the Type 4 password algorithm does not use PBKDF2 and does not use a salt, but instead performs a single iteration of SHA-256 over the user-provided plaintext password. This approach causes a Type 4 password to be less resilient to brute-force attacks.

These issues do not apply to devices running a Cisco IOS or Cisco IOS XE release without support for Type 4 passwords.

An authenticated, remote attacker could exploit the issue by logging in to an affected device and performing a brute-force attack. A successful attack could allow the attacker to access sensitive information on a targeted device.

Functional code that exploits the issue is publicly available.

Cisco has confirmed the issue in security response cisco-sr-20130318-type4; however software updates are not available.
 
Patches/Software
Software updates are not available.
 
Impact
An authenticated, remote attacker could exploit the issue to access sensitive information on a targeted device.
 
Safeguards
Administrators are advised to contact the vendor regarding future updates and releases.

Administrators are advised to replace any Type 4 passwords with a Type 5 password.

Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

Administrators can help protect affected systems from external attacks by using a solid firewall strategy.

Administrators are advised to monitor affected systems.
 
Alert History
 
Initial Release


Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
IntelliShieldSecurity Issue Alert Original Release Base

Associated Products:
N/A




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The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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