[NEWS] User Account Enumeration in Nortel Contivity VPN

From: SecuriTeam (support_at_securiteam.com)
Date: 11/16/04

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Date: 16 Nov 2004 18:40:58 +0200

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      User Account Enumeration in Nortel Contivity VPN
    ------------------------------------------------------------------------

    SUMMARY

    The Nortel Contivity Secure IP Services Gateways provide routing, IPSec
    and SSL VPN, firewall, bandwidth management, encryption, authentication,
    and data integrity for secure connectivity across managed IP networks and
    the Internet.

    The Nortel Networks Contivity VPN Client authentication error message
    provides more information than is necessary, thus allowing an attacker to
    discover existing users on the system.

    DETAILS

    Vulnerable Systems:
     * Contivity VPN Client for Windows versions prior to 5.01_030

    Immune Systems:
     * Contivity VPN Client for Windows version 5.01_030

    When a valid user name and an invalid password is given at login, the
    Contivity VPN Client displays "Login Failure due to: authentication
    failure". If an invalid user name is given, the Contivity VPN Client
    displays "Login Failed: Please verify the entered login information is
    correct".

    The different error messages could enable a malicious person to guess
    valid user names on the Contivity VPN/Firewall, and then run brute force
    attacks against these accounts. The underlying cause for this behavior is
    the IKE's aggressive mode protocol.

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:info@nii.co.in> Network
    Intelligence (I) Pvt. Ltd..
    The original article can be found at:
    <http://www.nii.co.in/vuln/contivity.html>
    http://www.nii.co.in/vuln/contivity.html

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