Wednesday, July 23, 2008

Two Denial of Service Vulnerabilities On Asterisk

Secunia and Digium have both published two DoS (Denial of Service) vulnerabilities across Asterisk products. Please read carefully and upgrade your servers to provide continuous service for yourself or your clients. Other Asterisk based product users, please contact your vendors.
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
* 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

Asterisk Open Source 1.2.x:
Update to version 1.2.30.

Asterisk Open Source 1.4.x:
Update to version

Asterisk Business Edition B.x.x.x:
Update to version B.2.5.4.

Asterisk Business Edition C.x.x.x:
Update to version C.1.10.3.

s800i (Asterisk Appliance) 1.0.x:
Update to version

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

Original Advisory:
Secunia Advisory


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