[Openswan Users] FW: NISCC Vulnerability Advisory IPSEC - 004033

[Ludwig Nussel]

mcr at xelerance.com wrote:
> >>>>> "Paul" == Paul Wouters <paul at xelerance.com> writes:
>     >>> Abstract: Three attacks that apply to certain configurations of
>     >>> IPsec have been identified. These configurations use
>     >>> Encapsulating Security Payload (ESP) in tunnel mode with
>     >>> confidentiality only, or with
> 
>     Paul> All normal configurations should always be using both
>     Paul> confidentiality and authentication.

parse_ipsec_sa_body() in spdb.c contains

	[...]
	switch (esp_attrs.auth)
	{
	    case AUTH_ALGORITHM_NONE:
		if (!ah_seen)
		{
		    DBG(DBG_CONTROL | DBG_CRYPT
			, DBG_log("ESP from %s must either have AUTH or be combined with AH"
			    , ip_str(&c->spd.that.host_addr)));
		    continue;   /* try another */
		}
		break;
	[...]

If that does what it looks like (I didn't check the full context)
then it's not possible to use ESP without authentication in
openswan.

>     >>> integrity protection being provided by a higher layer
>     >>> protocol. Some configurations using AH to provide integrity
>     >>> protection are also vulnerable.
> 
>     Paul> AH is not really used at all. In fact, we recommend people
>     Paul> still use ESP (and not AH or ESP NULL) even if they trust the
>     Paul> encryption in other layers (eg WEP or WPA), which they should
>     Paul> not.
> 
>   "higher layer" implies "TCP" to me.
> 
>     Paul> Perhaps Michael can give a more detailed answer,
> 
>   No, neither NISCC nor CERT have replied to my emails.
>   Where is the full text of the advisory?

http://www.kb.cert.org/vuls/id/302220

cu
Ludwig

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