AST-2012-006: Remote Crash Vulnerability in SIP Channel Driver

["Asterisk Security Team" <security@xxxxxxxxxxxx>]

               Asterisk Project Security Advisory - AST-2012-006

          Product         Asterisk                                            
          Summary         Remote Crash Vulnerability in SIP Channel Driver    
     Nature of Advisory   Remote Crash                                        
       Susceptibility     Remote Authenticated Sessions                       
          Severity        Moderate                                            
       Exploits Known     No                                                  
        Reported On       April 16, 2012                                      
        Reported By       Thomas Arimont                                      
         Posted On        April 23, 2012                                      
      Last Updated On     April 23, 2012                                      
      Advisory Contact    Matt Jordan < mjordan AT digium DOT com >           
          CVE Name        

    Description  A remotely exploitable crash vulnerability exists in the     
                 SIP channel driver if a SIP UPDATE request is processed      
                 within a particular window of time. For this to occur, the   
                 following must take place:                                   
                                                                              
                 1. The setting 'trustrpid' must be set to True               
                                                                              
                 2. An UPDATE request must be received after a call has been  
                 terminated and the associated channel object has been        
                 destroyed, but before the SIP dialog associated with the     
                 call has been destroyed. Receiving the UPDATE request        
                 before the call is terminated or after the SIP dialog        
                 associated with the call will not cause the crash            
                 vulnerability described here.                                
                                                                              
                 3. The UPDATE request must be formatted with the             
                 appropriate headers to reflect an Asterisk connected line    
                 update. The information in the headers must reflect a        
                 different Caller ID then what was previously associated      
                 with the dialog.                                             
                                                                              
                 When these conditions are true, Asterisk will attempt to     
                 perform a connected line update with no associated channel,  
                 and will crash.                                              

    Resolution  Asterisk now ensures a channel exists before performing a     
                connected line update, when that connected line update is     
                initiated via a SIP UPDATE request.                           
                                                                              
                In Asterisk versions not containing the fix for this issue,   
                setting the 'trustrpid' setting to False will prevent this    
                crash from occurring (default is False)                       

                               Affected Versions
                 Product               Release Series  
          Asterisk Open Source             1.8.x       All versions           
          Asterisk Open Source              10.x       All versions           
        Asterisk Business Edition          C.3.x       All versions           

                                  Corrected In
                    Product                              Release              
              Asterisk Open Source                   1.8.11.1, 10.3.1         
           Asterisk Business Edition                     C.3.7.4              

                                    Patches                         
                               SVN URL                              Revision  
   http://downloads.asterisk.org/pub/security/AST-2012-006-1.8.diff v1.8      
   http://downloads.asterisk.org/pub/security/AST-2012-006-10.diff  v.10      

       Links     https://issues.asterisk.org/jira/browse/ASTERISK-19770       

    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-2012-006.pdf and             
    http://downloads.digium.com/pub/security/AST-2012-006.html                

                                Revision History
          Date                 Editor                  Revisions Made         
    04/16/2012         Matt Jordan              Initial release.              

               Asterisk Project Security Advisory - AST-2012-006
              Copyright (c) 2012 Digium, Inc. All Rights Reserved.
  Permission is hereby granted to distribute and publish this advisory in its
                           original, unaltered form.