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DHCP Client Bash Environment Variable Code Injection (Shellshock)

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DHCP Client Bash Environment Variable Code Injection (Shellshock)

Disclosed
09/24/2014
Created
05/30/2018

Description

This module exploits the Shellshock vulnerability, a flaw in how the Bash shell handles external environment variables. This module targets dhclient by responding to DHCP requests with a malicious hostname, domainname, and URL which are then passed to the configuration scripts as environment variables, resulting in code execution.

Author(s)

  • scriptjunkie
  • apconole <apconole@yahoo.com>
  • Stephane Chazelas
  • Ramon de C Valle <rcvalle@metasploit.com>

Development

References

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/server/dhclient_bash_env
msf auxiliary(dhclient_bash_env) > show actions
    ...actions...
msf auxiliary(dhclient_bash_env) > set ACTION < action-name >
msf auxiliary(dhclient_bash_env) > show options
    ...show and set options...
msf auxiliary(dhclient_bash_env) > run 

Time is precious, so I don’t want to do something manually that I can automate. Leveraging the Metasploit Framework when automating any task keeps us from having to re-create the wheel as we can use the existing libraries and focus our efforts where it matters.

– Jim O’Gorman | President, Offensive Security

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