NTA Monitor

Latest News

Will IE6 be the next NT4?

1st October 2009 All penetration testers will remember the long tail of Windows NT 4.0, and how this operating system continued to be used long past the point when security updates stopped at the end of 2004. For many years the presence of an unpatchable NT4 server was a common issue in a penetration test report, and it is only now, almost five years after security support ended, that finding an NT4 system on a network is becoming a rare event. Read More

One in four web applications susceptible to high risk security flaws

7th September 2009 NTA Monitor has reported a 10% increase in the total number of web applications found to have at least one high-risk security issue... Read More

Organisations facing a changing threat landscape

20th July 2009 According to NTA Monitor's 2009 Annual Security Report, the average number of Internet security vulnerabilities is on the rise... Read More

The Return of the Insider Threat

1st July 2009 When NTA started security testing twelve years ago, the main focus was on the insider threat. There were many reports with statistics showing that most security breaches were due to insiders. By contrast there was very little focus on the external threat via Internet and third-party network links. Back then many companies did not even have a firewall. Read More

NTA Monitor discovers checkpoint FW-1 flaw

10,000 username guesses in 2 minutes 30 seconds

During the course of regular testing, NTA Monitor have discovered two serious flaws in Checkpoint Firewall-1, giving rise to both username guessing and sniffing issues.

Firstly, affected versions permit remote users to determine if a Firewall username is valid without having to know the associated password, enabling hackers to guess valid usernames using a dictionary attack. In tests of the flaw conducted by NTA Monitor, it took 2 minutes 30 seconds to check 10,000 usernames at a rate of 67 guesses per second using only 10% of a 2Mbps leased line. The guessing rate is mostly limited to by the Firewall CPU rather than by the Internet link speed. In effect, this means that companies using a hi-spec firewall server increase the speed at which an attacker can guess passwords.

In addition, VPN usernames are passed in the clear without encryption, allowing anyone who is able to sniff network traffic between VPN clients and the Firewall to observe usernames in transit. The flaws exploit the Internet Key Exchange (IKE) encryption scheme and affect all Checkpoint Firewall-1 systems of 4.0 or above.

This leaves the back door to the enterprise wide open to hackers. The biggest problem is that it is not necessary to send a password to obtain a reply from the Firewall. Given that both users and system administrators often chose weak passwords, it is likely that any attacker will be able to guess at least one password and thus gain access to the VPN - and from there most configurations easily allow full access to the company's resources.

The correct approach would be to wait until both username and password are supplied, and if either is incorrect, send a generic error message. We were surprised to find this flaw when this is standard security practice in many other authentication mechanisms, including Unix logon.

The vendor, Checkpoint and CERT/CC have been notified prior to public release.

Other security listings:

CVE-2002-1623

http://www.securiteam.com/securitynews/5TP040U8AW.html

Further detailed information and technical details on this vulnerability visit these links.

This advisory was first released on 30th January 2003.