Rapid7 Vulnerability & Exploit Database

Qmail SMTP Bash Environment Variable Injection (Shellshock)

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Qmail SMTP Bash Environment Variable Injection (Shellshock)

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

Description

This module exploits a shellshock vulnerability on Qmail, a public domain MTA written in C that runs on Unix systems. Due to the lack of validation on the MAIL FROM field, it is possible to execute shell code on a system with a vulnerable BASH (Shellshock). This flaw works on the latest Qmail versions (qmail-1.03 and netqmail-1.06). However, in order to execute code, /bin/sh has to be linked to bash (usually default configuration) and a valid recipient must be set on the RCPT TO field (usually admin@exampledomain.com). The exploit does not work on the "qmailrocks" community version as it ensures the MAILFROM field is well-formed.

Author(s)

  • Mario Ledo (Metasploit module)
  • Gabriel Follon (Metasploit module)
  • Kyle George (Vulnerability discovery)

Platform

Unix

Architectures

cmd

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/unix/smtp/qmail_bash_env_exec
msf exploit(qmail_bash_env_exec) > show targets
    ...targets...
msf exploit(qmail_bash_env_exec) > set TARGET < target-id >
msf exploit(qmail_bash_env_exec) > show options
    ...show and set options...
msf exploit(qmail_bash_env_exec) > exploit

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