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Executive Summary: Openswan-2 is vulnerable to a Denial of Service attack as reported by NISCC Vulnerability Advisory 273756/NISCC/ISAKMP


Nov 14th, 2005
Vendor response of the Openswan project to the following advisory:

NISCC Vulnerability Advisory 273756/NISCC/ISAKMP

CVE number: Unknown. Not requested or disclosed by reporter

Since we did not have prior knowledge of this vulnerability, and have not been given access to the test kit, so far we have only been able to partially analyse our IPsec implementation.

Versions of openswan-1 are (apparently) not vulnerable to this attack.

Versions of openswan-2 are (apparently) vulnerable to a Denial Of Service attack in two known cases.

One involves a crafted packet using 3DES with an invalid key length. One other is still unknown to us because no more information was provided. These two cases cannot be used to obtain elevated priviledges, since it is not possible to use these bugs to execute arbitrary code. These attacks are caught within our "assertion fail" verification code.

Today we have released openswan-2.4.2. This release fixes the 3DES related Denial Of Service attack.

We STRONGLY encourage CERT-FI and/or NISCC to give us access to the test kit if they are concerned about the second vulnerability and the impact of this advisory on the wide install base of Openswan-2 if those systems are left vulnerable to a DOS attack.

Openswan is the defacto IPsec software used on many Linux distributions, such as RedHat Linux, Fedora Linux, Debian, SuSe / Novell, Mandrake and many systems including embedded devices.

For further information, please see:
http://www.openswan.org/

NISCC 273756/NISCC/ISAKMP

Contact us at: security@xelerance.com

The Openswan team
Xelerance Corp.

Contact:
For further information, please contact Xelerance Corporation.
Update:
Openswan-2.4.4 was released to fix the second vulnerability leading to another Denial of Service attack. This DoS attack, like the one fixed in Openswan-2.4.2 requires Aggressive Mode with PSK authentication, which has always been strongly discouraged, to be configured on the server. Then a client can crash the server after authentication.

Updated information was sent to NISCC, and despite the fact that they have updated their security announcement with other vendor information, they have not added a single mention of Openswan.

NISCC has not requested a CVE number for this vulnerability.



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