bugtraq - Avahi 0.7 missing link-local checks in Legacy Unicast Responses cause information disclosure and makes DDoS with mDNS traffic reflection possible

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Message-ID: <CANTbKE_DkhZtUDp0D6rpFYX6QvT97NPU3DPWKzJ8oAN5wQ-UWw@mail.gmail.com>
Date: Tue, 27 Nov 2018 13:11:05 +0100
From: Krzysztof Burghardt <krzysztof@...ghardt.pl>
To: bugtraq@...urityfocus.com
Subject: Avahi 0.7 missing link-local checks in Legacy Unicast Responses cause
 information disclosure and makes DDoS with mDNS traffic reflection possible

Hi!

Avahi-daemon in Avahi through 0.7 inadvertently sends Legacy Unicast
Responses to IPv4 unicast queries with source addresses that are not
link-local, which allows remote attackers to cause a denial of service
(traffic amplification) or obtain potentially sensitive information
via port-5353 UDP packets.

send(IP(src="1.1.1.1",dst="192.168.1.1")/UDP(sport=53,
dport=5353)/DNS(rd=1,qd=DNSQR(qtype="PTR", qname="_ssh._tcp.local.")))

Author was notified by his bug tracker:
https://github.com/lathiat/avahi/issues/203

Regards,
-- 
Krzysztof Burghardt <krzysztof@...ghardt.pl>
http://www.burghardt.pl/