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AST-2014-019: Remote Crash Vulnerability in WebSocket Server



               Asterisk Project Security Advisory - AST-2014-019

         Product        Asterisk                                              
         Summary        Remote Crash Vulnerability in WebSocket Server        
    Nature of Advisory  Denial of Service                                     
      Susceptibility    Remote Unauthenticated Sessions                       
         Severity       Moderate                                              
      Exploits Known    No                                                    
       Reported On      30 October 2014                                       
       Reported By      Badalian Vyacheslav                                   
        Posted On       10 December 2014                                      
     Last Updated On    December 10, 2014                                     
     Advisory Contact   Joshua Colp <jcolp AT digium DOT com>                 
         CVE Name       

    Description  When handling a WebSocket frame the res_http_websocket       
                 module dynamically changes the size of the memory used to    
                 allow the provided payload to fit. If a payload length of    
                 zero was received the code would incorrectly attempt to      
                 resize to zero. This operation would succeed and end up      
                 freeing the memory but be treated as a failure. When the     
                 session was subsequently torn down this memory would get     
                 freed yet again causing a crash.                             
                                                                              
                 Users of the WebSocket functionality also did not take into  
                 account that provided text frames are not guaranteed to be   
                 NULL terminated. This has been fixed in chan_sip and         
                 chan_pjsip in the applicable versions.                       

    Resolution  Ensure the built-in HTTP server is disabled, upgrade to a     
                version listed below, or apply the applicable patch.          
                                                                              
                The change ensures that res_http_websocket does not treat     
                the freeing of memory when a payload length of zero is        
                received as fatal.                                            

                               Affected Versions       
                         Product                       Release  
                                                       Series   
                   Certified Asterisk                   11.6    All versions  
                  Asterisk Open Source                  11.x    All versions  
                  Asterisk Open Source                  12.x    All versions  
                  Asterisk Open Source                  13.x    All versions  

                                  Corrected In
          Product                              Release                        
     Certified Asterisk                       11.6-cert9                      
    Asterisk Open Source               11.14.2, 12.7.2, 13.0.2                

                                     Patches                         
                                SVN URL                              Revision  
   http://downloads.asterisk.org/pub/security/AST-2014-019-11.6.diff Certified 
                                                                     Asterisk  
                                                                     11.6      
   http://downloads.asterisk.org/pub/security/AST-2014-019-11.diff   Asterisk  
                                                                     11        
   http://downloads.asterisk.org/pub/security/AST-2014-019-12.diff   Asterisk  
                                                                     12        
   http://downloads.asterisk.org/pub/security/AST-2014-019-13.diff   Asterisk  
                                                                     13        

    Links  https://issues.asterisk.org/jira/browse/ASTERISK-24472             

    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-2014-019.pdf and             
    http://downloads.digium.com/pub/security/AST-2014-019.html                

                                Revision History
                      Date                       Editor      Revisions Made   
    December 10 2014                           Joshua Colp  Initial Revision  

               Asterisk Project Security Advisory - AST-2014-019
              Copyright (c) 2014 Digium, Inc. All Rights Reserved.
  Permission is hereby granted to distribute and publish this advisory in its
                           original, unaltered form.