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SMBLoris NBSS Denial of Service

The SMBLoris attack consumes large chunks of memory in the target by sending SMB requests with the NetBios Session Service(NBSS) Length Header value set to the maximum possible value. By keeping these connections open and initiating large numbers of these sessions, the memory does not get freed, and the server grinds to a halt. This vulnerability was originally disclosed by Sean Dillon and Zach Harding. DISCALIMER: This module opens a lot of simultaneous connections. Please check your system's ULIMIT to make sure it can handle it. This module will also run continuously until stopped.

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Module Name



  • thelightcosine
  • Adam Cammack <adam_cammack [at]>




Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':

msf > use auxiliary/dos/smb/smb_loris msf auxiliary(smb_loris) > show actions ...actions... msf auxiliary(smb_loris) > set ACTION <action-name> msf auxiliary(smb_loris) > show options and set options... msf auxiliary(smb_loris) > run