[Snort-sigs] false +ves for BLEEDING-EDGE P2P CHAT Skype VoIP Initialization

Matt Jonkman matt at ...2436...
Wed Apr 20 05:50:46 EDT 2005


I don't think we can count on the IPs remaining static, nor the ports. 
So I think we'll have to for now rely on the version check sig.

Other ideas?

Matt

stephane nasdrovisky wrote:
> Jason Haar wrote:
> 
>> random IP addresses, random ports,
>>
>> I'd say remove it, and instead rely on the "Skype VOIP Checking Version"
>> rules to catch at least some installs of it.
> 
> 
> An alternative could be to alarm upon access to skype's login server.
> The file C:\Documents and Settings\All Users\Application 
> Data\Skype\shared.xml (skype 1.0) contains these infos:
>      <EventServers>
>        <DirectlyConnected>1</DirectlyConnected>
>        <LastTCPServer>80.160.91.28:12350</LastTCPServer>
>        <LastUDPServer>212.72.49.142:12350</LastUDPServer>
>      </EventServers>
> 
>      <LoginServers>
>        <DirectlyConnected>1</DirectlyConnected>
>        <LastTCPServer>195.215.8.141:33033</LastTCPServer>
>      </LoginServers>
> 
> I don't know how skype uses these infos, but I guess it sometimes uses 
> them.
> This file also contains the p2p hosts cache (random ip addresses & ports)
> 
> alert ip $HOME_NET any -> 195.215.8.141 any (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP Login"; classtype:policy-violation; sid:9999988; rev:1;)
> alert tcp $HOME_NET any -> any 33033 (msg:"BLEEDING-EDGE P2P VOIP Skype 
> VoIP Login"; classtype:policy-violation; sid:9999989; rev:1;)
> alert udp $HOME_NET any -> any 33033 (msg:"BLEEDING-EDGE P2P VOIP Skype 
> VoIP Login"; classtype:policy-violation; sid:9999990; rev:1;)
> alert ip $HOME_NET any -> 80.160.91.28 any (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP Event"; classtype:policy-violation; sid:9999991; rev:1;)
> alert ip $HOME_NET any -> 212.72.49.142 any (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP Event"; classtype:policy-violation; sid:9999992; rev:1;)
> alert tcp $HOME_NET any -> any 12350 (msg:"BLEEDING-EDGE P2P VOIP Skype 
> VoIP Event"; classtype:policy-violation; sid:9999993; rev:1;)
> alert udp $HOME_NET any -> any 12350 (msg:"BLEEDING-EDGE P2P VOIP Skype 
> VoIP Event"; classtype:policy-violation; sid:9999994; rev:1;)
> alert ip $HOME_NET any -> 198.63.210.250 any (msg:"BLEEDING-EDGE P2P 
> VOIP Skype VoIP web site"; classtype:policy-violation; sid:9999995; rev:1;)
> alert udp $HOME_NET any -> 64.141.3.65 53 (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP dns"; classtype:policy-violation; sid:9999996; rev:1;)
> alert udp $HOME_NET any -> 195.50.213.37 53 (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP dns"; classtype:policy-violation; sid:9999997; rev:1;)
> alert udp $HOME_NET any -> 80.160.91.4 53 (msg:"BLEEDING-EDGE P2P VOIP 
> Skype VoIP dns"; classtype:policy-violation; sid:9999998; rev:1;)
> alert udp $HOME_NET any -> any 53 (msg:"BLEEDING-EDGE P2P VOIP Skype 
> VoIP dns"; content: "|05|skype"; depth: 50; classtype:policy-violation; 
> sid:9999999; rev:1;)
> 
> whois reports these netblocks:
> inetnum: 212.72.49.128 - 212.72.49.159
> netname: SKYPE-NL
> 
> inetnum: 195.215.8.0 - 195.215.8.255
> netname: TDC-HOSTING-OEBRO
> 
> inetnum: 80.160.88.0 - 80.160.91.255
> netname: TDC-INTERNET-SERVERCAMP-OPA
> 
> Nom :    skype.com
> Address:  198.63.210.250
> 
> nslookup -type=ns skype.com
> skype.com       nameserver = ns4.joltid.net
> skype.com       nameserver = ns5.joltid.net
> skype.com       nameserver = ns.joltid.net
> 
> ns5.joltid.net  internet address = 64.141.3.65
> ns.joltid.net   internet address = 195.50.213.37
> ns4.joltid.net  internet address = 80.160.91.4
> 
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by: New Crystal Reports XI.
> Version 11 adds new functionality designed to reduce time involved in
> creating, integrating, and deploying reporting solutions. Free runtime 
> info,
> new features, or free trial, at: http://www.businessobjects.com/devxi/728
> _______________________________________________
> Snort-sigs mailing list
> Snort-sigs at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/snort-sigs

-- 
--------------------------------------------
Matthew Jonkman, CISSP
Senior Security Engineer
Infotex
765-429-0398 Direct Anytime
765-448-6847 Office
866-679-5177 24x7 NOC
my.infotex.com
www.offsitefilter.com
www.bleedingsnort.com
--------------------------------------------


NOTICE: The information contained in this email is confidential
and intended solely for the intended recipient. Any use,
distribution, transmittal or retransmittal of information
contained in this email by persons who are not intended
recipients may be a violation of law and is strictly prohibited.
If you are not the intended recipient, please contact the sender
and delete all copies.




More information about the Snort-sigs mailing list