ASTERWEB Blog

AST-2016-002: File descriptor exhaustion in chan_sip

               Asterisk Project Security Advisory - AST-2016-002

         Product        Asterisk

         Summary        File descriptor exhaustion in chan_sip

    Nature of Advisory  Denial of Service

      Susceptibility    Remote Unauthenticated Sessions

         Severity       Minor

      Exploits Known    Yes

       Reported On      September 17, 2015

       Reported By      Alexander Traud

        Posted On       February 3, 2016

     Last Updated On    February 3, 2016

     Advisory Contact   Richard Mudgett <rmudgett AT digium DOT com>

         CVE Name       Pending                                               
    Description  Setting the sip.conf timert1 value to a value higher than

                 1245 can cause an integer overflow and result in large

                 retransmit timeout times. These large timeout values hold

                 system file descriptors hostage and can cause the system to

                 run out of file descriptors.                                 
    Resolution  Setting the sip.conf timert1 value to 1245 or lower will not

                exhibit the vulnerability. The default timert1 value is 500.

                Asterisk has been patched to detect the integer overflow and

                calculate the previous retransmission timer value.            
                               Affected Versions

                         Product                       Release

                                                       Series

                  Asterisk Open Source                  1.8.x   All versions

                  Asterisk Open Source                  11.x    All versions

                  Asterisk Open Source                  12.x    All versions

                  Asterisk Open Source                  13.x    All versions

                   Certified Asterisk                  1.8.28   All versions

                   Certified Asterisk                   11.6    All versions

                   Certified Asterisk                   13.1    All versions  
                                  Corrected In

          Product                              Release

    Asterisk Open Source                   11.21.1, 13.7.1

     Certified Asterisk                11.6-cert12, 13.1-cert3                
                                      Patches

                                 SVN URL                               Revision

   http://downloads.asterisk.org/pub/security/AST-2016-002-1.8.28.diff Certified

                                                                       Asterisk

                                                                       1.8.28

   http://downloads.asterisk.org/pub/security/AST-2016-002-11.6.diff   Certified

                                                                       Asterisk

                                                                       11.6

   http://downloads.asterisk.org/pub/security/AST-2016-002-13.1.diff   Certified

                                                                       Asterisk

                                                                       13.1

   http://downloads.asterisk.org/pub/security/AST-2016-002-1.8.diff    Asterisk

                                                                       1.8

   http://downloads.asterisk.org/pub/security/AST-2016-002-11.diff     Asterisk

                                                                       11

   http://downloads.asterisk.org/pub/security/AST-2016-002-12.diff     Asterisk

                                                                       12

   http://downloads.asterisk.org/pub/security/AST-2016-002-13.diff     Asterisk

                                                                       13        
    Links  https://issues.asterisk.org/jira/browse/ASTERISK-25397             
    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-2016-002.pdf and

    http://downloads.digium.com/pub/security/AST-2016-002.html