[srslte-users] RRC Security Mode Command Failure

[David Rupprecht]

Hi Pedro,

finally I got some time to record the cases. I attach you the log and
pcap files. In the first folder you find the trace of case 1 and 2. In
the second folder you find the traces of the 3 case. You are right, it
fails at the 3 case. I guess the k_enb is out of sync.

Best regards,
David

On 05.04.2018 11:53, Pedro Alvarez wrote:
> Hi David,
> 
> Thanks for reporting, I'll look into this.
> You're probably right, it's probably  a mis-match between the UE's and
> the EPC's UL NAS COUNT.
> 
> Could you try to do the following, just so I can be sure the problem
> is what I think it is:
> 
>   1 - Force an IMSI attach. You should be able to do this by taking
> out the SIM and putting it in again, or by putting the . (This should
> work fine.)
>   2 - Do a GUTI attach without restarting the EPC. You can do this by
> going in and out of  flight mode. (This should still work fine.)
>   3 - Re-start the eNB and the EPC and try the GUTI attach again.
> (This is probably where it's failing.)
> 
> Regards,
> Pedro
> 
> On Wed, Apr 4, 2018 at 1:45 PM, David Rupprecht <david.rupprecht at rub.de> wrote:
>> Hi,
>>
>> I'm using srsepc and srsenb in the latest version (1803). When trying to
>> connect a commercial UE with a programmable SIM card to the enB and EPC,
>> I get a RRC Security Mode Failure from the UE. My first guess, was that
>> the key_enb was not correctly transmitted, but this is not the case.
>> Maybe the k_enb is not correctly derived (NAS_UL_COUNT?), but I have not
>> checked that. Do you have any suggestions?
>>
>> With an older version of the srsEPC and the latest eNodeB the attach
>> works without any problems.
>>
>> I have attached the logs.
>>
>>
>> Best regards,
>> David
>> --
>> M.Sc. David Rupprecht
>>
>> Ruhr-University Bochum
>> Research Group Information Security
>> Universitätsstraße 150
>> ID 2/130
>> 44780 Bochum / Germany
>>
>> Phone: +49 234 / 32 - 23508
>> Web: www.infsec.rub.de
>>
>> _______________________________________________
>> srslte-users mailing list
>> srslte-users at lists.softwareradiosystems.com
>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>

-- 
M.Sc. David Rupprecht

Ruhr-University Bochum
Research Group Information Security
Universitätsstraße 150
ID 2/130
44780 Bochum / Germany

Phone: +49 234 / 32 - 23508
Web: www.infsec.rub.de
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