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Bugtraq archives for 2nd quarter (Apr-Jun) 1998: Re: CISCO PIX Vulnerability

Re: CISCO PIX Vulnerability

Rick Smith (rick_smithSECURECOMPUTING.COM)
Wed, 10 Jun 1998 13:02:11 -0500

>Another thing is that PIX is using DES in ECB mode. CISCO admits that
>"....ECB is not generally considered to be the best mode in which to
>employ DES,...." but you'll have to live with it. CISCO will not fix
>that so you'll have to buy future IPSEC/IKE products.

IMHO, the really, really nasty problem with ECB mode is that the data
stream is vulnerable to trivial substitution attacks. If the encrypted
traffic consists of administrative commands, it won't be that hard to
collect a modest but interesting dictionary of plaintext/ciphertext pairs.
Then the attacker can forge command strings without ever having to brute
force the key itself.

"Internet Cryptography" at bookstores or http:/www.visi.com/crypto/