asterisk - denial of service

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 1:1.6.2.9-2+squeeze6.

For the testing distribution (wheezy) and the unstable distribution
(sid), this problem has been fixed in version 1:1.8.13.0~dfsg-1.

We recommend that you upgrade your asterisk packages.