Secunia

Two vulnerabilities have been reported in Asterisk, which can be exploited by malicious people to cause a DoS (Denial of Service) or to conduct DoS attacks.

1) An error in the processing of IAX2 "POKE" requests can be exploited to consume all IAX2 call numbers via multiple "POKE" requests lacking an "ACK" packet sent in response to a "PONG" packet.

2) The firmware download protocol does not require a handshake, which can be exploited to send packets having 1040 bytes to arbitrary servers via a 40-byte packet with a spoofed source address.

The vulnerabilities are reported in the following products and versions:
* Asterisk Open Source 1.0.x (all versions)
* Asterisk Open Source 1.2.x (all versions prior to 1.2.30)
* Asterisk Open Source 1.4.x (all versions prior to 1.4.21.2)
* Asterisk Business Edition A.x.x (all versions)
* Asterisk Business Edition B.x.x.x (all versions prior to B.2.5.4)
* Asterisk Business Edition C.x.x.x (all versions prior to C.1.10.3)
* AsteriskNOW pre-release (all versions)
* Asterisk Appliance Developer Kit 0.x.x (all versions)
* s800i (Asterisk Appliance) 1.0.x (all versions prior to 1.2.0.1)

Solution
Asterisk Open Source 1.2.x:
Further details available in Customer Area

Provided and/or discovered by
1) The vendor credits Jeremy McNamara.
2) Tilghman Lesher, Digium

Original Advisory
http://downloads.digium.com/pub/security/AST-2008-010.html
http://downloads.digium.com/pub/security/AST-2008-011.html

Deep Links
Links available in Customer Area