Asterisk Project Security Advisory - AST-2012-015

         Product        Asterisk                                              
         Summary        Denial of Service Through Exploitation of Device      
                        State Caching                                         
    Nature of Advisory  Denial of Service                                     
      Susceptibility    Remote Unauthenticated Sessions                       
         Severity       Critical                                              
      Exploits Known    None                                                  
       Reported On      26 July, 2012                                         
       Reported By      Russell Bryant                                        
        Posted On       2 January, 2013                                       
     Last Updated On    January 2, 2013                                       
     Advisory Contact   Matt Jordan <mjordan AT digium DOT com>               
         CVE Name       CVE-2012-5977                                         

    Description  Asterisk maintains an internal cache for devices. The        
                 device state cache holds the state of each device known to   
                 Asterisk, such that consumers of device state information    
                 can query for the last known state for a particular device,  
                 even if it is not part of an active call. The concept of a   
                 device in Asterisk can include things that do not have a     
                 physical representation. One way that this currently occurs  
                 is when anonymous calls are allowed in Asterisk. A device    
                 is automatically created and stored in the cache for each    
                 anonymous call that occurs; this is possible in the SIP and  
                 IAX2 channel drivers and through channel drivers that        
                 utilize the res_jabber/res_xmpp resource modules (Gtalk,     
                 Jingle, and Motif). Attackers exploiting this vulnerability  
                 can attack an Asterisk system configured to allow anonymous  
                 calls by varying the source of the anonymous call,           
                 continually adding devices to the device state cache and     
                 consuming a system's resources.                              

    Resolution  Channels that are not associated with a physical device are   
                no longer stored in the device state cache. This affects      
                Local, DAHDI, SIP and IAX2 channels, and any channel drivers  
                built on the res_jabber/res_xmpp resource modules (Gtalk,     
                Jingle, and Motif).                                           

                               Affected Versions
               Product               Release Series    
         Asterisk Open Source             1.8.x        All Versions           
         Asterisk Open Source             10.x         All Versions           
         Asterisk Open Source             11.x         All Versions           
          Certified Asterisk             1.8.11        All Versions           
        Asterisk Digiumphones       10.x-digiumphones  All Versions           

                                  Corrected In
                 Product                              Release                 
          Asterisk Open Source               1.8.19.1, 10.11.1, 11.1.1        
           Certified Asterisk                      1.8.11-cert10              
          Asterisk Digiumphones                10.11.1-digiumphones           

                                    Patches                         
                               SVN URL                              Revision  
   http://downloads.asterisk.org/pub/security/AST-2012-015-1.8.diff Asterisk  
                                                                    1.8       
   http://downloads.asterisk.org/pub/security/AST-2012-015-10.diff  Asterisk  
                                                                    10        
   http://downloads.asterisk.org/pub/security/AST-2012-015-11.diff  Asterisk  
                                                                    11        

       Links     https://issues.asterisk.org/jira/browse/ASTERISK-20175       

    Asterisk Project Security Advisories are posted at                        
    http://www.asterisk.org/security                                          
                                                                              
    This document may be superseded by later versions; if so, the latest      
    version will be posted at                                                 
    http://downloads.digium.com/pub/security/AST-2012-015.pdf and             
    http://downloads.digium.com/pub/security/AST-2012-015.html                

                                Revision History
          Date                  Editor                 Revisions Made         
    19 November 2012   Matt Jordan               Initial Draft                

               Asterisk Project Security Advisory - AST-2012-015
              Copyright (c) 2012 Digium, Inc. All Rights Reserved.
  Permission is hereby granted to distribute and publish this advisory in its
                           original, unaltered form.