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TITLE:
Dnsmasq DHCP Lease File Denial of Service and DNS Cache Poisoning

SECUNIA ADVISORY ID:
SA14691

VERIFY ADVISORY:
http://secunia.com/advisories/14691/

CRITICAL:
Moderately critical

IMPACT:
Spoofing, Manipulation of data, DoS

WHERE:
>From remote

SOFTWARE:
Dnsmasq 2.x
http://secunia.com/product/4837/

DESCRIPTION:
Two vulnerabilities have been reported in Dnsmasq, which can be
exploited by malicious people to cause a DoS (Denial of Service) or
poison the DNS cache.

1) An off-by-one boundary error when reading the DHCP lease file can
be exploited by a malicious DHCP client to cause a buffer overflow by
supplying an overly long hostname and client-id.

Successful exploitation crashes Dnsmasq the next time it is started.

2) When receiving DNS replies, only the 16-bit ID is checked against
the current query. This can be exploited to poison the DNS cache if a
valid ID (randomly generated) is guessed by e.g. sending a flood of
DNS replies.

SOLUTION:
Update to version 2.21.
http://www.thekelleys.org.uk/dnsmasq/

PROVIDED AND/OR DISCOVERED BY:
1) The vendor credits Rob Holland.
2) Reported by vendor.

ORIGINAL ADVISORY:
http://www.thekelleys.org.uk/dnsmasq/CHANGELOG

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