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User Account Enumeration in Nortel Contivity VPN
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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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