[asterisk-security] AST-2018-003: Crash with an invalid SDP fmtp attribute

[Asterisk Security Team]

               Asterisk Project Security Advisory - AST-2018-003

         Product        Asterisk                                              
         Summary        Crash with an invalid SDP fmtp attribute              
    Nature of Advisory  Remote crash                                          
      Susceptibility    Remote Authenticated Sessions                         
         Severity       Minor                                                 
      Exploits Known    No                                                    
       Reported On      January 15, 2018                                      
       Reported By      Sandro Gauci                                          
        Posted On       February 21, 2018                                     
     Last Updated On    February 19, 2018                                     
     Advisory Contact   Kevin Harwell <kharwell AT diguim DOT com>            
         CVE Name       

    Description  By crafting an SDP message body with an invalid fmtp         
                 attribute Asterisk crashes when using the pjsip channel      
                 driver because pjproject's fmtp retrieval function fails to  
                 check if fmtp value is empty (set empty if previously        
                 parsed as invalid).                                          
                                                                              
                 The severity of this vulnerability is lessened since an      
                 endpoint must be authenticated prior to reaching the crash   
                 point, or it's configured with no authentication.            

    Resolution  A stricter check is now done when pjproject retrieves the     
                fmtp attribute. Empty values are now properly handled.        

                               Affected Versions       
                         Product                       Release  
                                                       Series   
                  Asterisk Open Source                  13.x    All Releases  
                  Asterisk Open Source                  14.x    All Releases  
                  Asterisk Open Source                  15.x    All Releases  
                   Certified Asterisk                   13.18   All Releases  

                                  Corrected In
          Product                              Release                        
    Asterisk Open Source               13.19.2, 14.7.6, 15.2.2                
     Certified Asterisk                      13.18-cert3                      

                                     Patches                          
                                SVN URL                               Revision  
   http://downloads.asterisk.org/pub/security/AST-2018-003-13.diff    Asterisk  
                                                                      13        
   http://downloads.asterisk.org/pub/security/AST-2018-003-14.diff    Asterisk  
                                                                      14        
   http://downloads.asterisk.org/pub/security/AST-2018-003-15.diff    Asterisk  
                                                                      15        
   http://downloads.asterisk.org/pub/security/AST-2018-003-13.18.diff Certified 
                                                                      Asterisk  
                                                                      13.18     

    Links  https://issues.asterisk.org/jira/browse/ASTERISK-27583             

    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-2018-003.pdf and             
    http://downloads.digium.com/pub/security/AST-2018-003.html                

                                Revision History
                     Date                       Editor       Revisions Made   
    January 30, 2018                         Kevin Harwell  Initial Revision  

               Asterisk Project Security Advisory - AST-2018-003
              Copyright (c) 2018 Digium, Inc. All Rights Reserved.
  Permission is hereby granted to distribute and publish this advisory in its
                           original, unaltered form.