Re: Multiple vulnerabilites in vendor IKE implementations, including Cisco,

[Sharad Ahlawat <sha () cisco com>]

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This is in response to the mail posted by Thor Lancelot Simon. The original 
mail is available at http://www.securityfocus.com/archive/1/347351 in which 
Thor has listed two issues. Documented below is Cisco's response to them.

Issue #1: Cisco addressed this issue as part of CSCdw87717 wherein the Cert 
Domain Name verification feature was implemented. This issue has been 
documented under the Cisco security advisory
http://www.cisco.com/warp/public/707/vpnclient-multiple2-vuln-pub.shtml.

Issue #2: This is a widely known common aspect of the Pre Shared Keys (PSK) 
authentication mechanism since 1999. With PSK, there is no way for a client 
to identify what is on the other side of the connection except that the other 
side has the same PSK.

The use of Digital Certificates as part of PKI for authentication or per user 
PSK are the only current solution to this aspect of using PSKs. It is a 
choice which network administrators must make between ease of use versus 
stronger security.

Additionally, there is another IETF draft specification that Cisco is in the 
process of evaluating, for its VPN 3000 product line, called CRACK (Challenge 
Response Authentication of Cryptographic Keys). More information available at 
http://www.nwfusion.com/links/Encyclopedia/C/722.html. Cisco is incorporating 
this authentication scheme in an upcoming release for the Cisco VPN 3000 
series concentrators. The Cisco VPN client should be supporting it in the 
future.

Brgds,
Sharad

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Sharad Ahlawat
Cisco Product Security Incident Response Team (PSIRT)
http://www.cisco.com/go/psirt
Phone:+1 (408) 527-6087
PGP-key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xC12A996C
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