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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi Joelle,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Of course I checked what our DNS servers are doing for such a query. They are doing the same as they are doing always if asking for a domain out of our scope and IP range. The server is replying with status: REFUSED.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In the meantime I had some e-mail dialog with Cisco. Without giving me details they mentioned there was an issue with a third party product GSLB/ADNS. In any case this mystery stopped since two days.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">// Hans <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-- <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b>From:</b> Joelle Maslak <jmaslak@antelope.net> <br>
<b>Sent:</b> Sunday, June 9, 2019 1:09 AM<br>
<b>To:</b> Mayer Hans <Hans.Mayer@iiasa.ac.at><br>
<b>Cc:</b> dns-operations@lists.dns-oarc.net; Eder Norbert <eder@iiasa.ac.at>; Undercoffer Joe <joseph.undercoffer@iiasa.ac.at><br>
<b>Subject:</b> Re: [dns-operations] what's ongoing with WEBEX and dot queries<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Do you respond to these queries with a large response (you might want to check). If you do, it may be a forged source packet asking for . so that your server sends a large "response" to WebEX, amplifying the bandwidth of the attacker.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Sat, Jun 8, 2019 at 1:49 PM Mayer Hans <<a href="mailto:Hans.Mayer@iiasa.ac.at">Hans.Mayer@iiasa.ac.at</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dear All, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Since 2019 06 05 around 10:00 UTC I see a much higher number of queries to our name servers for top level dot (.) <o:p></o:p></p>
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<p class="MsoNormal">This happened before too from anywhere but with an amount of queries of 5 to 10 times per day. Now we are in a range of average 2000 queries per hour up to 7200 queries per hour. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><img border="0" width="1090" height="251" style="width:11.3541in;height:2.6145in" id="gmail-m_13551555622232660014D65013A-AF91-4F23-AD0B-E467F28F070C" src="cid:image001.png@01D521CB.DFC70EE0"><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Interesting is that only one of our 4 DNS server is used for these queries. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">All these remote IP’s are coming from WEBEX. A reverse lookup ends with
<a href="http://something.webex.com" target="_blank">something.webex.com</a> <o:p></o:p></p>
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<p class="MsoNormal">The geo-locations are limited to 4 destinations <o:p></o:p></p>
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<p class="MsoNormal">US, <span style="color:#2D2D2D;background:white">San Jose</span> <o:p></o:p></p>
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<p class="MsoNormal">Netherlands<o:p></o:p></p>
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<p class="MsoNormal">Repulic of Singapore, Singapore <o:p></o:p></p>
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<p class="MsoNormal">China, <span style="color:#2D2D2D;background:white">Beijing</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Did anyone else register this obviously misconfigured DNS from Webex ? <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Kind regards <o:p></o:p></p>
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<p class="MsoNormal">Hans <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">— <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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