Debian Security Advisory

DSA-2493-1 asterisk -- denial of service

Date Reported:
12 Jun 2012
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 675204, Bug 675210.
In Mitre's CVE dictionary: CVE-2012-2947, CVE-2012-2948.
More information:

Several vulnerabilities were discovered in Asterisk, a PBX and telephony toolkit.

  • CVE-2012-2947

    The IAX2 channel driver allows remote attackers to cause a denial of service (daemon crash) by placing a call on hold (when a certain mohinterpret setting is enabled).

  • CVE-2012-2948

    The Skinny channel driver allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) by closing a connection in off-hook mode.

In addition, it was discovered that Asterisk does not set the alwaysauthreject option by default in the SIP channel driver. This allows remote attackers to observe a difference in response behavior and check for the presence of account names. (CVE-2011-2666) System administrators concerned by this user enumerating vulnerability should enable the alwaysauthreject option in the configuration. We do not plan to change the default setting in the stable version (Asterisk 1.6) in order to preserve backwards compatibility.

For the stable distribution (squeeze), this problem has been fixed in version 1:

For the testing distribution (wheezy) and the unstable distribution (sid), this problem has been fixed in version 1:

We recommend that you upgrade your asterisk packages.