The IAX2 protocol implementation in Asterisk Open Source 1.0.x, 1.2.x before 1.2.30, and 1.4.x before 1.4.21.2; Business Edition A.x.x, B.x.x before B.2.5.4, and C.x.x before C.1.10.3; AsteriskNOW; Appliance Developer Kit 0.x.x; and s800i 1.0.x before 1.2.0.1 allows remote attackers to cause a denial of service (call-number exhaustion and CPU consumption) by quickly sending a large number of IAX2 (IAX) POKE requests.

The remote host is affected by the vulnerability described in GLSA-200905-01 (Asterisk: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in the IAX2 channel     driver when performing the 3-way handshake (CVE-2008-1897), when     handling a large number of POKE requests (CVE-2008-3263), when handling     authentication attempts (CVE-2008-5558) and when handling firmware     download (FWDOWNL) requests (CVE-2008-3264). Asterisk does also not     correctly handle SIP INVITE messages that lack a 'From' header     (CVE-2008-2119), and responds differently to a failed login attempt     depending on whether the user account exists (CVE-2008-3903,     CVE-2009-0041).
  Impact :

    Remote unauthenticated attackers could send specially crafted data to     Asterisk, possibly resulting in a Denial of Service via a daemon crash,     call-number exhaustion, CPU or traffic consumption. Remote     unauthenticated attackers could furthermore enumerate valid usernames     to facilitate brute-force login attempts.
  Workaround :

    There is no known workaround at this time.

This security update fixes multiple security vulnerabilities in asterisk (CVE-2008-1897, CVE-2008-2119, CVE-2008-3263, CVE-2008-3264).

The version of Asterisk running on the remote host consumes an IAX2 call number while waiting for an ACK packet in response to a PONG packet.  By flooding the affected service with POKE requests, an unauthenticated, remote attacker can leverage this issue to exhaust all available call numbers and prevent legitimate IAX2 calls from getting through.

Update to 1.4.21.2 to fix CVE-2008-3263 / AST-2008-010 and CVE-2008-3264 / AST-2008-011. AST-2008-010: Asterisk IAX 'POKE' resource exhaustion - http://downloads.digium.com/pub/security/AST-2008-010.html AST-2008-011: Traffic amplification in IAX2 firmware provisioning system - http://downloads.digium.com/pub/security/AST-2008-011.html

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
38677	GLSA-200905-01 : Asterisk: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
33894	openSUSE 10 Security Update : asterisk (asterisk-5524)	Nessus	SuSE Local Security Checks	high
33576	Asterisk IAX2 (IAX) POKE Request Saturation Resource Exhaustion Remote DoS	Nessus	Denial of Service	medium
33569	Fedora 8 : asterisk-1.4.21.2-1.fc8 (2008-6676)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2008-3263

high

Tenable Plugins

high

high

medium

high