Kerio Personal Firewall Permits Remote Brute Force Password Determination
SecurityTracker Alert ID: 1013847|
SecurityTracker URL: http://securitytracker.com/id/1013847
(Links to External Site)
Date: Apr 30 2005
Disclosure of authentication information, User access via network|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): 4.1.2 and prior versions|
A vulnerability was reported in Kerio Personal Firewall. A remote user can conduct brute force attacks to determine user passwords in certain cases.|
A remote user with knowledge of at least one user password can connect to the administration port (44334) and conduct brute force attacks to determine a target user's password.
Passwords that are 5 characters or shorter can be determined quickly. The report indicates that the attack is not feasible for obtaining longer passwords.
The logging component may fail to log 40% of the events when an attack is being performed.
Systems using NT, Active Directory, or Open Directory authentication integration are at greater risk, because GINA.DLL re-login delay features are bypassed. As a result, the brute force guessing attack can occur more rapidly.
Secure Computer Group and dotpi.com Information Technologies Research Labs reported this vulnerability. Javier Munoz (Secure Computer Group) discovered this vulnerability.
A remote user with knowledge of at least one user password can determine other user passwords that are five characters or less.|
The vendor has issued a fixed version (4.1.3), available at:|
Vendor URL: www.kerio.com/ (Links to External Site)
|Underlying OS: Windows (Any)|
Source Message Contents
Subject: [CVE-2005-1062] Administration protocol abuse allows local/remote|
Secure Computer Group - University of A Coruna
-- x --
dotpi.com Information Technologies Research Labs
Document title: Administration protocol abuse allows
local/remote password cracking
Document revision: 1.0
Coordinated release date: 2005/04/29
Vendor Acknowledge date: 2005/02/25
Reported date: 2005/02/21
CVE Name: CAN-2005-1062
Other references: N/A
Impact: Local/remote password cracking
Recommendation: Update to latest version
Enforce network ACLs
Enforce password policies
Vendor: Kerio Technologies Inc.
o Kerio WinRoute Firewall up to and including 6.0.10
o Kerio Personal Firewall up to and including 4.1.2
o Kerio MailServer up to and including 6.0.8
Updates/Patches: Yes (see below)
1. Executive summary:
Kerio WinRoute Firewall, Kerio Personal Firewall and Kerio
MailServer drive a local/remote administration protocol in order
to manage the service.
This protocol can be abused in order to remotely retrieve user
credentials through a brute forcing technique. Passwords 1-5
characters long could be obtained quickly. As such, Kerio considers
them insecure and recommends enforcing password policies. The
attack is not practically usable for passwords longer than 5
characters. User logins must be previously known for this attack to
The logging component of the software can loose up to 40% of the
events when the attack is in place.
In order solve this problem, system administrators should enforce
network ACL security settings and user password policies. It is
also highly recommended to verify this settings as part of the
planning, installation, hardening and auditing processes.
New versions of the software solve this and other minor problems
so an upgrade is highly recommended.
2. Technical details:
Technical details and proof of concept code were provided to
3. Risk Assessment factors:
The attacker should have access to the administration ports:
o TCP/UDP 44333 - Kerio WinRoute Firewall Administration
o TCP/UDP 44334 - Kerio Personal Firewall Administration
o TCP/UDP 44337 - Kerio MailServer Administration
Network effective bandwidth between the system and the attacker is
also an important speed and success factor.
User logins must be previously known or previously brute forced
for this attack to be successful.
Special attention should be taken on environments on which NT,
Active Directory or Open Directory integration is in place.
GINA.DLL re-login delay features are bypassed and therefore the
brute forcing procedure is considerably quicker.
Local/Domain User Lock-out policies can help on contenting this
attack. Despite that, an user login denial of service can emerge
as a side effect.
The most risky scenarios are the ones in which the server machine
is shared among two or more interactive users/administrators or
those situations where Kerio service management have been
delegated to a third party.
The weakeness on the logging facility can be a target on its own
in order to hide any other attack that is being performed
Special care should be taken on such environments and every step
of the project: design, planning, deployment and management
should consider this security issues.
Privilege escalation, system and software tampering and the
ability to alter service configuration are all real issues and
all of them can be used as a second stage attack vector.
4. Solutions and recommendations:
Upgrade to the latest versions:
o Kerio Winroute Firewall 6.0.11 and above
o Kerio Personal Firewall 4.1.3 and above
o Kerio MailServer 6.0.9 and above
As in any other case, follow, as much as possible, the Industry
'Best Practices' on Planning, Deployment and Operation on this
kind of services.
5. Common Vulnerabilities and Exposures (CVE) project:
The Common Vulnerabilities and Exposures (CVE) project has
assigned the name CAN-2005-1062 to this issue. This is a
candidate for inclusion in the CVE list (http://cve.mitre.org),
which standardizes names for security problems.
1. Special thanks to Vladimir Toncar and the whole Technical Team from
Kerio Technologies (support at kerio.com) for their quick response
and professional handling on this issue.
3. The whole Research Lab at dotpi.com and specially to Carlos Veira.
3. Secure Computer Group at University of A Coruna (scg at udc.es),
and specially to Antonino Santos del Riego.
Javier Munoz (Secure Computer Group) is credited with this discovery.
 Kerio Technologies Inc.
 Kerio WinRoute Firewall Downloads & Updates
 Kerio Personal Firewall Downloads & Updates
 Kerio MailServer Downloads & Updates
 Secure Computer Group. University of A Coruna
 Secure Computer Group. Updated advisory
 dotpi.com Information Technologies S.L.
 dotpi.com Research Labs
Copyright (c) 2002-2005 Secure Computer Group. University of A Coruna
Copyright (c) 2004-2005 dotpi.com Information Technologies S.L.
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(scg at udc.es) and (info at dotpi.com).
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