[NEWS] Checkpoint VPN-1/SecureClient ISAKMP Buffer Overflow
From: SecuriTeam (support_at_securiteam.com)
To: firstname.lastname@example.org Date: 5 Feb 2004 19:06:03 +0200
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Checkpoint VPN-1/SecureClient ISAKMP Buffer Overflow
"Checkpoint VPN-1 server and Checkpoint VPN clients
(SecuRemote/SecureClient) collaborate to provide VPN access to corporate
networks for remote client computers. VPN-1 is the VPN component commonly
deployed on Checkpoint Firewall-1 installations. The IKE component of
these products allows for the unidirectional or bidirectional
authentication of two remote nodes as well as the negotiation of
cryptographic capabilities and keys."
A buffer overflow condition has been found when attempting to handle large
certificate payloads. A remote attacker may exploit this flaw to remotely
compromise any VPN-1 server and/or client system running
SecureClient/SecureClient. Successful compromise of the VPN-1 server can
lead directly to complete compromise of the entire Checkpoint Firewall-1
* VPN-1 Server 4.1 up to and including SP6 with OpenSSL HotFix
* SecuRemote/SecureClient 4.1 up to and including build 4200
* Firewall-1 NG FP1 or greater
Internet Key Exchange (IKE) is used to negotiate and exchange keys for
encrypted transport or tunneling of network traffic over a Virtual Private
Network (VPN). The network protocol used to facilitate this exchange is
the Internet Security Association and Key Management Protocol (ISAKMP).
The vulnerability exhibits itself when handling ISAKMP packets with large
Certificate Request payloads. This can be triggered by a remote
unauthenticated attacker during the initial phases of an IKE negotiation.
It is not necessary to impersonate a known VPN server to exploit client
systems, and VPN servers are equally vulnerable. As this attack does not
require any interaction with the target system, it can be performed via
UDP with a spoofed source address concealing the identity of an attacker.
There is insufficient bounds checking and a classic stack overflow is
possible. From there the way is paved for remote code execution and hence
full compromise of the server.
There is no effective workaround for this vulnerability. Upgrading to the
NG versions of VPN-1 Server and SecuRemote/Client will remove this
vulnerability. Checkpoint no longer supports the versions of VPN-1 and
SecuRemote/SecureClient affected by this vulnerability. Checkpoint
recommends that all affected users upgrade to Firewall-1 NG FP1 or
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