[asterisk-dev] AST-2013-007: Asterisk Manager User Dialplan Permission Escalation

[Asterisk Security Team]

               Asterisk Project Security Advisory - AST-2013-007

         Product        Asterisk                                              
         Summary        Asterisk Manager User Dialplan Permission Escalation  
    Nature of Advisory  Permission Escalation                                 
      Susceptibility    Remote Authenticated Sessions                         
         Severity       Minor                                                 
      Exploits Known    None                                                  
       Reported On      November 25, 2013                                     
       Reported By      Matt Jordan                                           
        Posted On       December 16, 2013                                     
     Last Updated On    December 16, 2013                                     
     Advisory Contact   David Lee < dlee AT digium DOT com >                  
         CVE Name       Pending                                               

    Description  External control protocols, such as the Asterisk Manager     
                 Interface, often have the ability to get and set channel     
                 variables; this allows the execution of dialplan functions.  
                                                                              
                 Dialplan functions within Asterisk are incredibly powerful,  
                 which is wonderful                                           
                                                                              
                 for building applications using Asterisk. But during the     
                 read or write execution, certain diaplan functions do much   
                 more. For example, reading the SHELL() function can execute  
                 arbitrary commands on the system Asterisk is running on.     
                 Writing to the FILE() function can change any file that      
                 Asterisk has write access to.                                
                                                                              
                 When these functions are executed from an external           
                 protocol, that execution could result in a privilege         
                 escalation.                                                  

    Resolution  Asterisk can now inhibit the execution of these functions     
                from external interfaces such as AMI, if live_dangerously in  
                the [options] section of asterisk.conf is set to no.          
                                                                              
                For backwards compatibility, live_dangerously defaults to     
                yes, and must be explicitly set to no to enable this          
                privilege escalation protection.                              

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

                                  Corrected In
                  Product                              Release                
            Asterisk Open Source              1.8.24.1, 10.12.4, 11.6.1       
         Asterisk with Digiumphones              10.12.4-digiumphones         
             Certified Asterisk                1.8.15-cert4, 11.2-cert3       

                                          Patches                            
                                  SVN URL                                       Revision     
http://downloads.asterisk.org/pub/security/AST-2013-007-1.8.diff             Asterisk 1.8    
http://downloads.asterisk.org/pub/security/AST-2013-007-10.diff              Asterisk 10     
http://downloads.asterisk.org/pub/security/AST-2013-007-10-digiumphones.diff Asterisk        
                                                                             10-digiumphones 
http://downloads.asterisk.org/pub/security/AST-2013-007-11.diff              Asterisk 11     
http://downloads.asterisk.org/pub/security/AST-2013-007-1.8.15.diff          Certified       
                                                                             Asterisk 1.8.15 
http://downloads.asterisk.org/pub/security/AST-2013-007-11.2.diff            Certified       
                                                                             Asterisk 11.2   

       Links     https://issues.asterisk.org/jira/browse/ASTERISK-22905       

    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-2013-007.pdf and             
    http://downloads.digium.com/pub/security/AST-2013-007.html                

                                Revision History
          Date                 Editor                  Revisions Made         
    12/16/2013         Matt Jordan              Initial Revision              

               Asterisk Project Security Advisory - AST-2013-007
              Copyright (c) 2013 Digium, Inc. All Rights Reserved.
  Permission is hereby granted to distribute and publish this advisory in its
                           original, unaltered form.