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TFTP Server for Windows 1.4 ST WRQ Buffer Overflow

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TFTP Server for Windows 1.4 ST WRQ Buffer Overflow

Disclosed
03/26/2008
Created
05/30/2018

Description

This module exploits a vulnerability found in TFTP Server 1.4 ST. The flaw is due to the way TFTP handles the filename parameter extracted from a WRQ request. The server will append the user-supplied filename to TFTP server binary's path without any bounds checking, and then attempt to check this path with a fopen(). Since this isn't a valid file path, fopen() returns null, which allows the corrupted data to be used in a strcmp() function, causing an access violation. Since the offset is sensitive to how the TFTP server is launched, you must know in advance if your victim machine launched the TFTP as a 'Service' or 'Standalone' , and then manually select your target accordingly. A successful attempt will lead to remote code execution under the context of SYSTEM if run as a service, or the user if run as a standalone. A failed attempt will result a denial-of-service.

Author(s)

  • Mati Aharoni
  • Datacut

Platform

Windows

Development

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 exploit/windows/tftp/tftpserver_wrq_bof
msf exploit(tftpserver_wrq_bof) > show targets
    ...targets...
msf exploit(tftpserver_wrq_bof) > set TARGET < target-id >
msf exploit(tftpserver_wrq_bof) > show options
    ...show and set options...
msf exploit(tftpserver_wrq_bof) > exploit

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